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CC Exhibit 5/12/15 Item No. 2 Study Session regarding Proposed Fiscal Year 2015-2016 Budget Karen B. Guerina`' From: grenna5000@yahoo.com Sent: Monday, May 11, 2015 11:50 AM To: City Council Cc: grenna5000@yahoo.com Subject: City Council Meeting and Planning Commission Meeting on May 12 Dear City Council: I hope that there will be little or no conflict in timing between the City Council meeting and the Planning Commission meeting that are both scheduled for Tuesday, May12. I have items I want to follow on both schedules and I am concerned that there may be an overlap of the two meetings. It is difficult to figure out when items will be presented in the two different rooms if the meetings begin to overlap timewise. If the City Council meeting is not over by the time the Planning Commission meeting starts at 6:45 PM, could you have a way to let the public know what is happening in the Planning Commission meeting while the City Council meeting is going on and what item the Planning Commission is currently on? Maybe they could have a simulcast of the Planning Commission meeting being broadcast on some device in the Community Hall lobby? I am hopeful that two meetings will not overlap in time and that the public can follow both meetings back to back with little or no overlap in time. Thank you very much. Sincerely, Jennifer Griffin 1 I/, Ips Karen B. Guerin From: tfolkner@comcast.net Sent: Monday, May 11, 2015 6:43 AM To: Rod Sinks; Barry Chang; Gilbert Wong; Savita Vaidhyanathan; Darcy Paul Cc: tfolkner@comcast.net; Laura Folkner Subject: Cupertino needs safer streets for pedestrians and bicyclists Dear Council Member— Thank you for your focus and efforts to make Cupertino safe for our students and citizens who walk and bike to schools, shops and throughout their neighborhoods. I remember Jeffery Steinwedel, 46, who was killed on Dec. 2, 1996 when he was run over by a truck pulling double trailers on Stevens Canyon Road, just outside the Stevens Creek Quarry. The trucks that use Foothill and Stevens Canyon road for access to the Voss quarry and the Lehigh Cement plant are a danger to autos, bicyclists, and pedestrians. Cupertino needs to use available funds to make Foothill safer for everyone. remember Ethan Wong, 15, who was killed Oct. 28, 2014 on McClellan Road by another truck. I urge you to.- Budget o:Budget the remaining $800K in funds to complete 2011 Bike/Ped plan. There are a number of additional BikePed Safety projects on the table, including additional green lane painting near our city's schools, improved cross-walk lighting at McClelland/Rose Blossom and at Alves/Stelling. I trust that you will approve these projects also. Initiate, fund and launch the development of the Long Term Bicycle/Pedestrian Strategic Plan and process; Earmark $10 million of the projected budget surplus to build infrastructure that will help ensure Cupertino is a safer and more desirable place to walk and bike, and a better place to live for many decades to come.The re-engineering of existing through-ways and intersections such as Foothill, McClelland, Bubb, Stelling and Rainbow roads will make our community safer and more desirable place to live. Troy and Laura Folkner 33 year Cupertino residents 22424 Ramona Court lane painting near our city's schools, improved cro ss-walk lighting at McClelland/Rose Blossom and at Alves/Stelling . I trust that you wi II approve these projects also. Initiate, fund and launch the development of the Long Term Bicycle/Pedestrian Strategic Plan and process; Earmark $ 10 million of the projected budget surplus build infrastructu re that will help ensure Cupertino is a safer and more desirable plac e to walk and bike, and a better place to live for many decades to come. The re-engineering of existing through-ways and intersections such as McClelland , Bubb, Stellin g and Rainbow roads will make our community safer and more desirable place to live. Thank you for your service to tour Cupertino Commun ity City of Cupertino FY 2015-16 Proposed Budget Study Session May 12, 2015 X51.I yfS CUPERTINO Agenda ■ Changes to the Budget and Budget Process ■ Five Year General Fund Forecast ■ General Fund Revenue ■ Fund Balance Agenda ■ Recommended Expenditures by Department ■ Staffing ■ Issues and Challenges ■ Next Steps Changes to the Budget Document and Process ■ New System Implemented ■ Use of Open Gov ■ Performance Measures CC 5/12/15 General Fund Revenues Expenditures and Transfers Out 5900 -- Sa0.0 $7010 60 550.0 $50.0 f 540.0 5400.0 $30.0 ---- - $30.0 $2040 -- - S20.0 MA - - SS00 - I FY15 Final FY16 S- FY09Ac��is FY1p AR0.als FV 11 Actuals FV1Z ActwltlaJFY13Actuals FY14Actuais Budget Proused ye P . OncTlme Special Projects 50.5 $0.4 S0.4 50.4 { $0.8 55.7 $2.4 $7.6 r wGeneral Fund Transfers Out S7.1 $9.4 $7-0 56.4 I S8.2 $22.9 $3L6 $6.4 General Fund Expenditures $31.8 532.6 533.3 $34.4 $35.7 $35.8 543.5 $50.5 >Ceneral Fund Revenue $41.9 $36.1 544.6 $47.6 $54.7 $73.9 $56.1 $68.2 General Fund Revenue -All Categories $100,000,000 5911000,000 $80,000,DD0 - - S711000,aoo -- $60,000,000 - $50,000,000 - - 540,000,000 -- 530,000,000 $20,000,000 $50,000,000 $ 2014 15 2010-11 2011-12 2012-13 2013-14 Final 2014-15 2015-16 2016-17 2D17-18 2018-19 2019-20 Actuals Actuals Actuals A[tuak Budget Amended Proposed Projection PrpjatflOn Projection Projection idTotal General Fund Revenue $44,587,48 547,567,98 554,661,79$73.833,72 $56,112,50 $88,353,41 568,162,30 S67,248,0D 57Q919,00 572,912,00 574,954,00 3 CC 5/12/15 General Fund Revenue Sales Tax w000.000 $25,000,000 $20000,000 $15,000,000 $1Q000,000 S5,ODD,OOD S. 201611 .1-2 2OU-00-14 2014-15 2014-13 1 2OLS-16 2OW17 1: 2017-18 1 201819 2019-20 Adwh is &Wsts 20Projection Projection Projection Projection Ws Actuate Final Budget Amended Proposed I a Sales Ta 6.46 5I8,721,66 S1979403 $18,288)00 518,2811,00 52Q36000 I $22,371,00 522,975,00 521s9s.00 $24232,00 I Property Tax $22.000.000 $20.000.000 $18,000,000 $16,000,000 $14,000,000 512.000.000 S10,000,000 $8,000,000 $6.000,000 $4,000,000 52,000,000 $- 15 anal 30WIS 111I5-16 201617 2017-I8 1 261629 3M21 2010-11ktuals 2011-32Actumalls 2022-13Actu* -14 Actusk sudpt Amended Propowd Pr*cdw pt*don ftWftn P.Jft, wSalesTax SIL650,137 SIL915.066 j SIA523.M .$14405.997 SIS067,000 S15,067A00 $14055,000 $14697,000 S19,134.000 i $19. A00 S2t16s5.ODO 4 CC 5/12/15 Transient Occupancy Tax $7,000.000 $6,000,000 - _- - - - — S5,000,000 54,000,000 $3.000.000 - _— $2.000,000 $1.000,000 -- _. 2011-35 Hnld 2011.15 2015-16 101617 10U-16 3DI$-16 2DW3D 201611 Actuals 2031.12 Actuals 2012-13 Actuate 2013.14 Aetwk Budpt Amended Propofed Pmkctw Pru"Mn - PmWgon Projection .Saksifu $2,536,501 53,112,934 $3,769,504 54,590.1%�..St,61Q000 ..-f1,S1400D 55,072,010 $7,256,000 $7,1B1,000 $7,690.000 57,B98,000 General Classification Balance CLASSIFICATION 2013-14 2014-15 2014-15 2014-15 Ch..g� 2015-16 Non Spendable loans R<Keiwbk• 7,296,6]7 937,071 3,296,637 1,032,275 7,032,275 Pre ald 1lems 66,428 66,428 66,428 66,428 66,428 Tdal Non Spendable 3,363,065 1,003,439 3,363,065 1,098,703 - 1,098,703 Restrkh-d IaubBc Accea Television 695,561 761,693 761,653 Total Restrirted - 695,564 - ]61,693 - ]61,653 Committed None m this classification Total Committed - - - - - - Ecenomk Uncertaintvl 72,500,01111 1A,000,000 IA,lUO,OW 1N,O110,0V0 1,IX10,IX)0 19,0(M1,IXH1 F anomk Uncertainty 11 1,400,000 - - - - - Economlc Fluctuation 2,000,000 1,400,000 7,4110,000 7,400,000 - 1,400,I1U0 PERS 500,000 700,000 100,000 100,000 - 100,000 One Time Revnue - - - - - Fquipment - Reserve lar Fncumbrancz 1,267,233 172,659 11,081,064 2,OR7,064 2,OR7,064 Revenue LlabOity 3,920,000 8,940,000 - - - - Gencral 0uilding 1,148,549 603,739 - - - - WolkRoadlransportatanStudy 1,000,OW 1,IX1U,OW 1,WU,0()D 1,000,000 - 1,000,W0 1-280 Tnil Stud 250,000 250,000 250,000 250,000 250,000 Total Assigied 23,985,782 30,466,398 31,831,069 22,831,064 1,0110,000 23,831,069 Unassiend 18,331,549 836,219 795,2(17 11,297,956 - 13,945,246 TOTAL FUND BALANCE 45,680,396 33,001,620 35,989,416 35,989,416 1,000,000 39,636,666 5 CC 5/12/15 Fund Balance • Classification 2013-14 I I 5 YEAR FORECAST Actuals Adopted Amended 2015-2016 2016-2017 2017-2018 2018-2019 2019-2020 Beginning Fund Balance 45,680,396 45,680,396 33,001,620 35,989,416 39,636,706 41,337,412 43,038,118 47,687,856 Non Spendable 3,363,065 1,003,439 1,098,703 1,098,703 1,098,703 1,098,703 1,098,703 1,098,703 Restricted - 695,564 76],693 761,693 761,693 761,693 761,693 761,693 Assigned 23,985,782 30,466,398 22,831,064 23,831,064 38,977,0]6 40,677,722 45,327,460 50,585,689 Unassigned 18,331,549 836,219 11,297,956 13,945,246 500,000 500,000 500,000 500,000 Total Ending Fund Balance 45,680,396 33,001,620 35,989,416 39,636,706 41,337/312 43,038,118 47,687,856 52,946,085 Citv Council and Commissions Adrnu f tWiw Capital Projects 770,677 _4,868,861 17.652.994 1 -� 4% Lai,Enforcement 16% 10.994.684 10°a blic Affairs 4588,468 4% Non-Departmental dministratfveSenues 16.040,523 5,096,478 160° 4% Recreation and Community Services 12,415,242 11% Planning and Comm tv Public Developrnmt 24.711.718 14,309,990 22% 12°, 6 CC 5/12/15 cc CC Ccnhrak and rgaCo,Abeal�� #Y C1Y CopnCY ertd Comruaona 778677 tnBe�ues 1 catnn "..._.50.$16567 p� 5 33 Genual Fund 68.162.303 Adm,Malnwk and Contr,d S,rv�av,.1 831. 0 Admiik fbn 6686666 Adorn CDntngencvese Cosl Aax—goo 34' Adm.0m 1 Uses.Debt Caplal8 Sped PreFtt 555689,6 end Co '356 Law Enforcement 10694 886 Lew Enbne�nt M,Meb nvect S Iamx�i0686 s .%0 SpewlRevanue/6.186.98+ 1,," Kan SbR Com, y8y 127 - Li,—i 6 Pemas.6.171.000 Punk:AKanMCetnennatl2 dd�au Sens,i ap$6.512 Pubbc AKans 4.588.668 P—Aram ptneAUses Deft U al� DewAI PmtFn X69 tp5 flee of Abney 8 Pmp"749 530 —OeW Service 3 167.538 AdmblNtawa Sarvees 5.096.178 e• Law Enloexmfra Cantingende,8 Coat Ab:.ero 62♦09 Adorn Svc,Stell CD,h'2 ga123 3665 99— ,;:t AdmndS,Sivre,Cot ntnk all C 3 Cosf AAo atom 361:54 y Racrtaton—d Com• dy SIN—12.415.242 Bence, integavemmenlet+612.123 keaaa4on Ste-Cosh.5226153 Recrealon A+aterek and CoC dd Sell 1 489.631 Rer 1v,C to genues 6 Cost Abuton 1 269 834 ■CegN PreFc, tan OO+et l/,e,Oeot.Capdal b Spe<ol Pmkd.lag 595 CMfpes lot Serene,18.916.5 ` \- PIaM+in9 and CDn,tun4Y DevebDment 14,309,990. all: .,.. \- '1,. Plsnn CP1ta'11.•7450� Phnnnq rl.xnebi-amcea'T.155162— FnesbfDAeaurcs 1. _ PlannatB Cont,rpen��'Oat fi157a5 Ptannng OMer lees.Deol.Gp1el 8 Spet�a T yla.al3� Enteryn,e g.5r7.0 r' PuDXc Wors,24?11,74 'Ttemfeis ln.175Y'.. PPOs:wb8u SUff Cosb'.10.578.536 Public Yb AS Melerieh ell G Idd,t sell .7 102.586 M 1n4mal5eno.6.401,015 PuDac Nbrtp Olhn UA 1ConbnBm�ra�8 SCoirA.-z','3 1"21 — Non OepartrwW.35,893.51 r Nan Deeennenln itanslee Out 12633.222■ tbn Departmental Omer Ux,Deb:.Cap1e16 Specnl project-$3$60.295 City Council and Administration Commission 4,868,864 8,610,,985 mental Non-Dep6770,677 -8% 13% Law Enforcement 10,994,684 _17% Public Affairs 1% Public Works Administrative 16,427,167 Services 257 2,851,808 4 .Recreation and Community Services Planning and 6,157,107 Community 10% Development 13,371,463 21% 7 CC 5/12/15 Council . • Commissions Category FY1.4-15 FY 15-16 Variance Final Budget Proposed Budget EXPENDITURES 690,454 770,677 80,223 • FY15-16 Request Use of Funds Deer Hollow $10,000 Fund Operation of Deer Hollow Farm Historical Society $10,000 Upgrade Museum Exhibit Display a "Salute to the WWII Flying Tigers of China' exhibit Upgrades to Traveling Trunk Program Possible Membership Drive Euphrat Museum $10,000 he funds awarded will go towards exhibition and outreach program expenses and will greatly help enable s to offer the one-of-a-kind exhibitions and programs e are known for. KMVT 1 $40,000 Oo Digital Campaign Round 2! (Cameras) 8 CC 5/12/15 Administration Category FY14-15 FY 15-16 Variance Final Budget Proposed Budget EXPENDITURES $3,817,005 $4,868,864 $1,051,859 7 S ' SILICON VALLEY CCE PARTNERSHIP Why CCE? 7.3•° • ,.8•,° ,.5°,• 0.4°,° Streamline project-level GHG CEQA review in Energy Transportation (§15183.5) ■Off-Road Sources • Achieve General Plan/GPA Sustainability 33.9% ■Solid Waste Element Policies, align w/growth estimates ■Wastewater • Achieve local AB 32 targets • Build regional partnerships CA IOU Electricity Pricing-Commercial Sector • Access funding • Achieve cost savings and/or price stability s a ( t°.O anal SnfdE(a.5%1 / A -ENt EMa California Energy Almanac Energy Information Agency 18_0�1-65P 1P tie ti3:1 l I NRG Energyyr 9 CC 5/12/15 SILICON VALLEY CCE PARTNERSHIP What is it? tj LA Allnow 11• • source delivery customer SCP PG&E YOU buys and builds delivers energy, choice, cleaner cleaner energy repairs lines energy, local supplies control and competitive rate 01' SILICON VALLEY CCE PARTNERSHIP Where is it? IlllSvSonoma LA N C A Clean Power `M C E CENERGY lean Energy My community.My choice. Local. Renewable. Ours. THE POWER TO CHOOSE Who's involved ? OF SUAVV,,,.� LEAN )_I j �� '� ��ENERGY� Pacific Energy CITY OF MOUNTAIN VIEW CUPERTINo Advisors, Inc. 10 CC 5/12/15 SILICON VALLEY CCE PARTNERSHIP Progress & Next Steps Initial Study completed Website launched — www.svcleanenergy.org Consultant team identified for Technical Assistance, Program Development, and Community Engagement Data request sent to PG&E Additional cities agreed to be included in data request: Campbell, Gilroy, Los Altos, Los Altos Hills, Los Gatos, Monte Sereno, Morgan Hill, Saratoga Next SV CCE Partnership agreement to implement Technical Feasibility Study phase and support JPA launch — July 2015 s 6> SILICON VALLEY " CCE PARTNERSHIP Program111111110 Phase 1a: Phase 1b:Technica?k Phw�2:_CCE Phase 3: Initial Study___1 Feasibility Study Dev't L CCE Launch • ID potential agency • ID partners& • Enabling Ordinance • Staffing and Org partners funding • JPA Formation setup • ID opportunities, • Technical Study: • Energy Svcs Pricing • Energy and other costs, and risks load and rate and Procurement ( Service Contracts • Investigate other analysis, economics, . Implementation Plan ' Customer j CCAs supply options, to PUC notifications and • Inform communityenvironmental service • Service Agmt with outcomes and gather feedbac Conservation& 400 . . reven ' Expand JPA Commence Service AW 0Tech Study 0Initial JPA Imp'n Plan Decision Formation to CPUC 11 CC 5/12/15 V- A LEAN Key Findings jk&ENERGY�z • Existing CCE Programs are Performing Well • Current Energy Market is Strong • Significant Potential to Meet/Exceed Local CAP goals • Anticipated Rate Savings in the Near Term • Risks Exist But Can Be Mitigated • Encourage Partnership to Move Forward w/ Tech Study — Quantitative analysis of load data and program potential Growing Interest Around the State do-*CLEAN ENERGY • is Poised 0 Operational CCAs MCE Chan Enorgy Lnnalstar Chd Energy Sonoma Cher,P— Exploring/in Process Alameda County Butte County Cay of Arcata/Htntboldt C—nty City of Davls/yolo C—dy ?�. Cay of San Dlego Clty/Calrttyof San F-6—. Cay of Sunnyvale/Silicon Valley P.rtnership Contra Costa County LA County/S—th Bay Cons h— Lake Cou dy Mcndociro County Monterey Bay C—Mm ty Power(Trl-Courrtyt • Napa County Clues arh m San Bam—County San Dlego County San Luis 6—Po/Morro Bay • Sm Mateo County Santa Barba2 County' Solan Caunty Vontura County 12 CC 5/12/15 Market Conditions/Utility Rate Trends ►E LEAN ENERGY • Wholesale power and natural gas prices are at historic lows • Utilities are fully resourced through 2020 and thus excess power is available • Affordable financing available due to low interest rates LEAN CCE Generation Rate Comparison ENERGY. Generation Rate "' fight Gr e MCE Deep Green .• $0.098 $0.079 $0.089 • $0.102 $0.079 $0.089 .I $0.099 $0.077 $0.087 AG-1(agricultural) $0.103 $0.089 $0.099 e PG&E SCP/Clean Start SCP/Evergreen $0.097 $0.071 $0.106 A-1(small commercial) $0.102 $0.076 $0.111 E-19(large industrial) $0.102 $0.077 $0.112 AG-1(agricultural) $0.108 $0.081 $0.116 Note:No guarantee will always be lower;existing CCE programs changes rate once a year compared to multiple times a year for PG&E. 13 CC 5/12/15 LEAN MCE 2015 Residential Rates 1► 508 kWh • E-1/Res- 1 Light GreenDeep • 0• 00• Solar Delivery $44.37 $44.37 $44.37 3i Generation $49.50 $40.13 $45.21 $72.14 PG&E Fees - $6.27 $6.27 $6.27 Total Cost $93.87 $90.77 $95.85 $122.78 • Delivery rates stay the same • Generation rates vary by service option • PG&E adds exit fees on CCA customer bills • Even with exit fees, total cost for Light Green is less than PG&E LEAN SCP 2015 Commercial Rates ��ENERGY Example Commercial Electric Charges PG&E* CleanStart EverGrzer i Based on abusiness using 3313/o 1000/0 1.500 kWh per month on the COM-1(A-1)rate Renewable Energy Ren—,ble Enc—ly Renewab le Energy Electric Generation (all customers) $153.42 $114"24 PG&E Elec trlc Delivery' (all customers) Additional PG&E Fees • • (SCP customers only) ,PG&E fees aro calculated by Sonoma Clean Power using rate data provided by PG&E effect—on January 1,2015. 'Based on 2014 forecasted data.as reported by PG&E The Power Content comparison.linked at left.contains 2013 actual data for PGB.E. 14 CC 5/12/15 LEAN MCE and SCP Financial Conditions ENERGY Both CCE Programs are fiscally sound Total Revenue $145,933,000 $165,495,000 Expenses $141,433,000 $148,588,000 Cost of Energy $129,522,000 $130,100,000 Cost of Administration 4% 3.5% Net Increase in Reserves $4,500,000 $16,907,000 CCE and the Environment ►ELEAN ENERGY Electric Power Generation Mix" min Renewable 22% -- % 1001° • 64ornass&Biowaste 4% 9% 0% • C-eCAherrTvil 5% 15% 100% • E3igittle hydmi:4ectric 2% D% 0% <- .r elect" 5% 0% 0% 6% 9% 0% ua o IL 0%e28% W". 0%o.0-2 ,J0°. 0'a 0°00% SS genK data repr�e-1,;;R �s prove rn the"L7r.U11ep0 o t a ra Commission: r Source Disclosure PProgr3m.'SCP's generation data is forecast for 2014. Total CO2 Emissions from Electricity Sales per Megawatt-Hour— Po70Pounds The COz ct the energy gen r 2012.sem. kaci G&E in SCP's CG=emission data is farecart for 2014- 15 CC 5/12/15 -- � LEAN Local Innovations and Opportunities �ErvERCY� • Energy Efficiency: Multiple ways for CCEs to fund programs; eg: MCE obtained $5.5M by becoming an EE program administrator • Battery Storage: MCE announces partnership with Tesla for home energy storage • Local Power Projects: MCE building 10.5 MW PV on Chevron brownfield site • SCP building a 12.5 MW "Floatovoltaics" PV project on wastewater ponds at County Water Agency. Risks Related to CCELEAN • Financial Risk • Competitive and Pricing picl/ /nnf_i ,f Rot-oc • Market Exposure • Regulatory Risk -AiA • Political Risk :i ,,LN4 16 CC 5/12/15 LEAN Recommendations for SVCCEP izrE.NERGY. 1. Articulate CCE goals and objectives 2. Tech study to consider SVCCEP's large commercial/ industrial load, which presents both opportunities and challenges not found in MCE and SCP territories. 3. Engage other SCC cities to participate in Tech Study 4. Start stakeholder and community engagement now 5. If SVCCEP moves ahead, form JPA sooner than later. v+w w.svcl<anenergynrg SILICON VALLEY CCE PARTNERSHIP 0, What is Community CCE Benefits for The Path Ahead Choice Energy? Silicon Valley SVCCE Parinersbry is condmtmg an inaal A new Ne—y Prov""'woWC D —ely A local CCE co prove move renewalLe sNRy an0 other cores are cons"erirg nm M Pam--v Si on Valley Pow"'.eevebp be al renewable energy lo-9 c omrr.rtiti"s. W�ojecr�ar"red—9reen 1—911,e wlvle na�aming competrtrve 17 CC 5/12/15 Law Enforcement Category FY14-15 FY 15-16 Variance Public Final Budget Proposed Budget EXPENDITURES $10,175,62 $10,994,68 $ 819,06 • irs Category FY14-15 FY 15-16 Variance Final Budget Proposed Budget EXPENDITURES $4,203,524 $4,588,468 $384,944 18 CC 5/12/15 Administrative Services Category FY14-15 FY 15-16 Variance Final Budget Proposed Budget EXPENDITURES $4,083,70 $5,096,47 $1,012,771 Recreation a • Community Services Category FY14-15 Final FY 15-16 Variance Budget Proposed Budget EXPENDITURES $11,506,514 $12,415,242 $908,72 19 CC 5/12/15 Planning . • Community D ' •• Category FY14-15 FY 15-16 Variance Final Budget Proposed Budget EXPENDITURES ment $8,438,29 $ 14,309,99 $5,871,69 Public • Category FY14-15 FY 15-16 Variance Final Budget Proposed Budget EXPENDITURES $30,343,125 $24,711,71 $(5,631,407) 20 CC 5/12/15 Non-Departmental Category FY14-15 FY 15-16 Variance Final Budget Proposed Budget EXPENDITURES $32,883,28 $18,040,523 $(14,842,763) • Ten Year Staffing and Population Growth Chart 62,000 4.25 ---..- _.- - - 60,000 58,000 3.75 56,000 54,000 3.25 a 52,000 a 2.75 50'0)0 48,000 FY 0405 FY 05.06 FY 0607 FY 07-08',FY 0&09 FY 09-10 FY 10.11 FYi1-32 FY 12-13 FY 13-14 FY14-15'FY 15-16 46,000 Actuals Actuals Actuals Actuals Actuals Actuals Actuals Actuals Actuals Actuals Final Proposed Budget Budget a�Population 51,695 51,698 52,552 53,396 54,278 58,302 59,295 60,009 60,189 60.550 60,550 60,550 —s-Staff Per SOOOResidents 3-01 3.07 3.06 3.05 3.00 2.79 2.74 2.71 2.74 2.75 2.80 2.99 Total Staff(FTE) 155.75 158.75 160.75 162.72 162.75 162.75 162.75 162.75 164.75 '. 166.75 169.75 180.75 21 CC 5/12/15 • • loll • . � . • Dept(s) Classification Salaries Benefits Total Funding Source/Purpose Costs City Deputy City 109,208 42,712 $151,920 General Fund Transition Attorney Attorney to new City Attorney (1 Year Limited Term) City Analyst(Utility 97,066 42,949 $140,015 General Fund Manager Analyst 2 Year Implementation of Limited Term) Climate Action Plan City Analyst 97,066 42,949 $140,015 General Fund Manager (Sustainability Implementation of Program Analyst) Climate Action Plan • Dept(s) Classification Salaries Benefits Total Funding Costs Source/Purpose Community Plan Check 109,788 42,100 $151,888 General Fund and Pass Development Engineer Thru Revenues (3 Year Limited Increased demand for Term) services driven by increased development in the City Community Senior Code 85,228 36,005 $121,233 General Fund Development Enforcement Increased demand for and Public Officer inspections driven by Works increased development in the Cit 22 CC 5/12/15 • Dept(s) Classification Salaries Benefits Total Funding Costs Source/Purpose Public Affairs GIS Technician 88,145 39,873 $128,018 General Fund Replaces 2 part time employees Recreation and Recreation 71,554 31,034 $102,588 General Fund Community Coordinator Service Enhancement Services Recreation and Case Manager 74,820 32,452 $107,272 General Fund Community In lieu of contractor Services • Dept(s) Classification Salaries Benefits Total Costs Funding Source/Purpose Public Associate Civil 104,037 39,987 $144,024 General Fund Works Engineer(3 Year- Focus on bicycle and Limited Term) pedestrian safety and the transportation impact fee Public Environmental 81,725 33,878 $115,603 Non-Point Works Programs Assistant Source/Resource Recovery Fund Increased Regulatory Requirements Public Maintenance Worker 55,947 28,553 $84,500 Non-Point Works I/II Source/Resource Recovery Fund Increased Regulatory Re uirements 23 Issues and Challenges ■ Sales Tax Volatility ■ Retirement ■ Unmet Needs Next Steps ■ FY 2014-15 • Third Quarter Report May 19th ■ FY 2015-16 • Hearing and Adoption June 2nd • First Quarter Report Nov 2015 Accessing the Budget ■ Online at www.cupertino.org/budget CUPERTIN . � ■ Copies available at City Hall and the Cupertino Library St.I yJ,r CUPERTINO C (2- CUPERTINO City Council May 12, 2015 Proposed FY 2016 j A a�� r_ I L l' w .F Capital Improvement Program l Completed Projects Completed Projects FY2012 Projects completed by June 30,2012 Description Description 2011-12 Annual Curb,Gutter&Sidewalk 2011-12 Annual Pavement Management Repairs &ADA Ramps 2011-12 Annual Minor Storm Drain Blackberry Farm Infrastructure Upgrade Improvements Civic Center Master Plan Framework Electric Vehicle Charging Station Linda Vista Pond Improvements-Study McClellan Ranch/Simms Master Plan Update McClellan Ranch 4H Sanitary Connection Permanente Creek Safe Routed to School-Garden Gate Stocklmeir Orchard Irrigation Various Minor Intersection Traffic Signal Various Park Path and Parking Lot Repairs& Battery Backup System Resurfacing-Phase 1 Completed Projects FY2013 Projects completed by June 30,2013 Description Description Emergency Van Upgrades McClellan Ranch Repairs&Painting McClellan Road Sidewalk Study Traffic Management Studies-3 Intersections Various Park Path and Parking Lot Repairs& Various Trail Resurfacing at School Sports Resurfacing-Phase 2 Fields-Phase 1 Various Trail Resurfacing at School Sports Wilson Park Irrigation System Renovation Fields-Phase 2 City of Cupertino~City Council-Proposed FY 2016 Capital Improvement Program -May 12, 2015 2 Completed Projects FY2014 Projects completed by June 30,2014 Description Description Library Book Drop-off Shade Canopy McClellan Ranch-Barn Evaluation& Renovation Plan McClellan Ranch-Historic Structures McClellan Ranch Preserve Signage Program Assessment Mary Avenue Dog Park Phase 1 Solar Assessment-Public Building Senior Center-Various Improvements Sorts Center-Various Improvements Stevens Creek Corridor Park Phase 2 Various Park Path Repairs-Phase 3 Various Traffic Signal/Intersection Various Trail Resurfacing at School Sports Modifications Fields-Phase 3 Project was suspended after initial analysis due to a proposed Santa Clara County Library District project to replace existing automated book-drop system in the next 18 months. Completed Projects FY2015 Projects completed by June 30,2015 Description Description Accessibility Transition Plan Update Bicycle and Pedestrian Facility Improvements Calabazas Creek(Bollinger Rd.)Outfall Repair Install Speed Bumps-Vista and Lazaneo Dr McClellan Ranch Environmental Education McClellan Road Sidewalk Improvements- Center,Blacksmith Shop, Shelter,Solar & Phase 1 Restroom Upgrades Priority Green Bike Lane Improvements Public Building Solar Installation-Service Center Quinlan Community Center Fiber Installation Quinlan Center Interior Upgrades Sports Center Tennis Court Retaining Wall Replacement City of Cupertino- City Council-Proposed FY 2016 Capital Improvement Program -May 12, 2015 3 City of Cupertino FY 2016 - FY 2020 Proposed CIP Project Summary Total Budget Prior Years FY 2016 FY 2017 FY 2018 FY 2019 FY 2020 Priority 1 ADA Improvements 375,000 75,000 75,000 75,000 75,000 75,000 Bicycle and Pedestrian Facility Improvements 1,206,000 423,000 700,000 83,000 Bicycle Transportation Plan Update 50,000 50,000 Bridge Rehabilitation- Minor 165,000 165,000 Bubb Road (Elm Ct.)Storm Drain Improvements 1,635,000 1,635,000 Citywide Park and Recreation Master Plan 500,000 500,000 Fiber Network Expansion for Signal Interconnect 132,000 132,000 Initial Civic Center Projects 2,200,000 2,200,000 Lawrence-Mitty Park 8,270,994 8,270,994 Library Expansion 500,000 500,000 Mary Avenue Complete Streets 3,690,000 28,000 3,662,000 McClellan Ranch- Pedestrian, Parking, Landscape Improvements 358,000 358,000 McClellan Ranch West-Simm's House Removal 220,000 220,000 McClellan Rd. Sidewalk Improvement-Phase 2 2,035,000 1,100,000 935,000 Monta Vista Storm Drain System 2,000,000 2,000,000 Quinlan Community Center-Cupertino Rm Lighting Replacement 108,000 108,000 Quinlan Community Center-Fire Alarm Control Panel Upgrade 135,000 135,000 Senior Center- Exercise Room Wood Floor Replace. 79,000 79,000 Senior Center-Mary Avenue Landscaping 156,000 50,000 106,000 Sport Center Sport Court 250,000 250,000 Sports Center- Resurface Tennis Courts(18 courts) 1,735,000 735,000 1,000,000 Stevens Creek Blvd. at Perimeter Road Turn Pocket Extension 215,000 110,000 105,000 Stevens Creek Corridor Park Chain Master Plan-McClellan to Stevens 535,000 535,000 Creek Blvd Storm Drain Master Plan Update 330,000 330,000 Street Median Irrigation& Plant Replacement 660,000 220,000 220,000 220,000 Wilson Park- Building &Landscape Improvements 205,000 65,000 140,000 Wilson Park- Ball Safety Netting Screens 65,000 65,000 Wilson Park- Bleacher Shade Canopies 1 190,000 190,000 Total Budget Prior Years FY 2016 FY 2017 FY 2018 FY 2019 FY 2020 Priority 2 Blackberry Farm -Splash Pad 690,000 70,000 620,000 Pasadena Ave Public Improvements(Between Granada& Olive) 827,000 827,000 Sidewalk Improvements-Orange&Byrne 1,888,000 500,000 1,388,000 Priority 3 Blackberry Farm Golf Course Renovations 1,043,000 550,000 493,000 Blacksmith Shop Forge Restoration-Design 60,000 60,000 Service Center-Parking Lot Modification 176,000 176,000 Priority 4 Joll man Park Irrigation Upgrade 2,313,000 330,000 1,983,000 McClellan Ranch-Construct Trash Enclosure 154,000 154,000 McClellan Ranch-Community Garden Improvements 1,060,000 96,000 964,000 Memorial Park-Tennis Court Restroom Replacement 448,000 448,000 Memorial Park Master Plan & Parking Study 150,000 150,000 Memorial Park Phase 1 -Conceptual Design 250,000 250,000 Monta Vista Park- Play Areas 1,334,000 1,334,000 Monta Vista Park-Turf Reduction 1,757,000 700,000 1,057,000 Portal Park-Renovation Master Plan 55,000 55,000 Portal Park Phase 1 -Conceptual Design 75,000 75,000 Quinlan Community Center-Turf Reduction/Landscape Modifications 2,493,000 750,000 743,000 1,000,000 Sports Center- Exterior Upgrades 250,000 250,000 Sports Center- Interior Upgrades 270,000 20,000 250,000 Stevens Creek Bank Repair-South of SCB-Conceptual Design 100,000 100,000 Tennis Court Resurfacing-Various Parks 1,103,000 588,000 280,000 235,000 Traffic Signal: Foothill/1-280 SB Off-ramp 100,000 100,000 Wilson Park- Renovation Master Plan 55,0001 1 55,000 Wilson Park Phase 1 -Conceptual Design 1 75,0001 1 75,000 Unfunded Projects for Future Consideration Blackberry Farm — Play Area Improvements Cricket Batting Cage Linda Vista Pond Repair McClellan Ranch — Barn Renovation McClellan Ranch Preserve Stevens Creek Access Memorial Park Phase 1 — Construction Portal Park — Phase 1 - Construction Stevens Creek Trail Bridge Over UPRR Stevens Creek Trail to Linda Vista Park Stocklmeir House Preservation and Restoration Stocklmeir Legacy Farm — Phase 1 Improvement Tank House Completion (Nathan Hall) Wilson Park Phase 1 — Construction City of Cupertino-City Council ~Proposed FY 2016 Capital Improvement Program -May 12, 2015 4 n r� x t a a r •A<, M PACTS answers to common questions about the science of climate change NATIONAL RESEARCH COUNCIL OF THE NATIONAL ACADEMIES ,.c ". CONTENTS Part I. Evidence for Human-Caused Climate Change 2 How do we know that Earth has warmed? 3 How do we know that greenhouse gases lead to warming? 4 How do we know that humans are causing greenhouse gases to increase? 6 How much are human activities heating Earth? 9 How do we know the current warming trend isn't caused by the Sun? 11 How do we know the current warming trend isn't caused by natural cycles? 12 What other climate changes and impacts have been observed? 15 The Ice Ages 18 Part II. Warming, Climate Changes, and Impacts in the 21st Century and Beyond 20 How do scientists project future climate change? 21 How will temperatures be affected? 22 v . r .. How is precipitation expected to change? 23 How will sea ice and snow be affected? 26 How will coastlines be affected? 26 How will ecosystems be affected? 28 How will agriculture and food production be affected? 29 Part III. Making Climate Choices 30 How does science inform emissions choices? 31 What are the choices for reducing greenhouse gas emissions? 32 What are the choices for preparing for the impacts of climate change? 34 Why take action if there are still uncertainties about the risks of climate change? 35 Conclusion 36 r z a i 11 ' i EVIDENCE IMPACTS CHOICES just what is climate? Climate is commonly thought of as the expected weather conditions at a given location over time. People know when they go to New York City in winter, they should take a coat. When they visit the Pacific Northwest, they take an umbrella. Climate can be measured at many geographic scales—for example, cities, countries, or the entire globe—by such statistics as average temperatures, average number of rainy days, and the frequency of droughts. Climate change refers to changes in these statistics over years, decades, or even centuries. Enormous progress has been made in increasing our understanding of climate change and its causes, and a clearer picture of current and future impacts is emerging. Research is also shedding light on actions that might be taken to limit the magnitude of climate change and adapt to its impacts. This booklet is intended to help people understand what is known about climate change. First, it lays out the evidence that human activities, especially the burning of fossil fuels, are responsible for much of the warming and related changes being observed around the world. Second, it summarizes projections of future climate changes and impacts expected in this century and beyond. Finally, the booklet examines how science can help inform choices about managing and reducing the risks posed by climate change. The information is based on a number of National Research Council reports (see inside back cover), each of which represents the consensus of experts who have reviewed hundreds of studies describing many years of accumulating evidence. F �5 r .. he overwhelming But how has this conclusion been reached? Climate science, majority of climate like all science, is a process of collective learning that relies on the careful gathering and analyses of data, scientists agree that the formulation of hypotheses, the development of human activities, models to study key processes and make testable especially the burning predictions, and the combined use of observations and models to test scientific understanding. of fossil fuels (coal, oil, Scientific knowledge builds over time as new and gas), are responsible observations and data become available. for most of the climate Confidence in our understanding grows if multiple lines of evidence lead to the same conclusions, or change currently being if other explanations can be ruled out. In the case of observed. climate change, scientists have understood for more than a century that emissions from the burning of fossil fuels could lead to increases in the Earth's average surface temperature. Decades of research have confirmed and extended this understanding. 2 How do we know that Earth has warmed? sdentists have been taking widespread measure- changes in the instruments taking the measure- ments of Earth's surface temperature since ments or by other factors that affect local tempera- around 1880. These data have steadily improved ture, such as additional heat that has come from and, today, temperatures are recorded by ther- the gradual growth of cities. mometers at many thousands of locations, both on These analyses all show that Earth's average the land and over the oceans. Different research surface temperature has increased by more than groups, including the NASA Goddard Institute for 1.4°F (0.8°C)over the past 100 years, with much Space Studies, Britain's Hadley Centre for Climate of this increase taking place over the past 35 years. Change, the Japan Meteorological Agency, and A temperature change of 1.4°F may not seem like NOAA's National Climate Data Center have used much if you're thinking about a daily or seasonal these raw measurements to produce records of fluctuation, but it is a significant change when long-term global surface temperature change you think about a permanent increase averaged (Figure 1).These groups work carefully to make across the entire planet. Consider, for example, sure the data aren't skewed by such things as that 1.4°F is greater than the average annual Global Land–Ocean Temperature Index .6 —�Annual Mean .4 —5–year Running Mean T o .2 d .0 a H —.2 —.4 1880 1900 1920 1940 1960 1980 2000 d6sm NASA's Global Surface Temperature Record Esti- (bottom left)Climate monitoring stations on land and sea, • mates of global surface temperature change, relative such as the moored buoys of NOAAs Tropical Atmosphere to the average global surface temperature for the Ocean(TAO)project, provide real-time data on tempera- period from 1951 to 1980,which is about 14°C(571) ture, humidity,winds,and other atmospheric properties. from NASA Goddard Institute for Space Studies show Image courtesy of TAO Project Office, NOAA Pacific Marine a warming trend over the 20th century.The esti- Environmental Laboratory. (right)Weather balloons,which mates are based on surface air temperature measure- carry instruments known as radiosondes,provide verti- ments at meteorological stations and on sea surface cal profiles of some of these same properties throughout temperature measurements from ships and satellites. the lower atmosphere.Image©University Corporation for The black curve shows average annual temperatures, Atmospheric Research. (top left)The NOAA-N spacecraft, and the red curve is a 5-year running average.The launched in 2005,is the fifteenth in a series of polar- green bars indicate the margin of error,which has orbiting satellites dating back to 1978.The satellites carry been reduced over time.Source: National Research instruments that measure global surface temperature and Council 2010a other climate variables. Image courtesy NASA 3 temperature difference between Washington, D.C., of the atmosphere and of the ocean and land and Charleston, South Carolina, which is more surfaces. Satellite data are also used to study shifts in than 450 miles farther south. Consider, too, that precipitation and changes in land cover. a decrease of only 9°F (5°C) in global average Even though satellites measure temperature very temperatures is the estimated difference between differently than instruments on Earth's surface, and today's climate and an ice age. any errors would be of a completely different In addition to surface temperature, other parts of nature, the two records agree. A number of other the climate system are also being monitored carefully indicators of global warming have also been (Figure 2). For example, a variety of instruments are observed (see pp.15-17). For example, heat waves used to measure temperature, salinity, and currents are becoming more frequent, cold snaps are now beneath the ocean surface.Weather balloons are shorter and milder, snow and ice cover are used to probe the temperature, humidity, and winds decreasing in the Northern Hemisphere, glaciers in the atmosphere.A key breakthrough in the ability and ice caps around the world are melting, and to track global environmental changes began in the many plant and animal species are moving to cooler 1970s with the dawn of the era of satellite remote latitudes or higher altitudes because it is too warm sensing. Many different types of sensors, carried to stay where they are.The picture that emerges on dozens of satellites, have allowed us to build a from all of these data sets is clear and consistent: truly global picture of changes in the temperature Earth is warming. How do we know that greenhouse gases lead to warming? As early as the 1820s, scientists began to ap- energy is then radiated upward from Earth's surface preciate the importance of certain gases in in the form of heat. In the absence of greenhouse regulating the temperature of the Earth (see Box 1). gases, this heat would simply escape to space, Greenhouse gases—which include carbon dioxide and the planet's average surface temperature (CO,), methane, nitrous oxide, and water vapor— would be well below freezing. But greenhouse act like a blanket in the atmosphere, keep- gases absorb and redirect some of ing heat in the lower atmosphere. ' , this energy downward, keeping Although greenhouse gases ,i� ' heat near Earth's surface. As comprise only a tiny fraction concentrations of heat- of Earth's atmosphere, they trapping greenhouse are critical for keeping the vq gases increase in the planet warm enough to atmosphere, Earth's support life as we know it natural greenhouse (Figure 3). effect is enhanced Here's how the (like a thicker blanket), "greenhouse effect" causing surface works: as the Sun's energy temperatures to rise hits Earth, some of it is (Figure 3). Reducing the reflected back to space, but levels of greenhouse gases most of it is absorbed by the in the atmosphere would land and oceans. This absorbed -_ _ , cause a decrease in surface temperatures. 4 AMPLIFIED WARMING (I)Sunlight brings energy into the climate system;most of it is (6)Higher concentrations of COr and other absorbed by the oceans and land. "greenhouse"gases trap more infrared energy in the (2)Heat(infrared energy)radiates outward from the warmed atmosphere than occurs naturally.The additional heat surface of the Earth. =here the atmosphere and Earth's surface. (3)Some of the infrared energy is absorbed by greenhouse gases in the atmosphere,which re-emit the energy in all directions. (4)Some of the infrared energy further warms the Earth. (5)Some of the infrared energy is emitted into space. a Amplification of the Greenhouse Effect The greenhouse effect is a natural phenomenon that is essential to keeping the Earth's surface warm. Like a greenhouse window,greenhouse gases allow sunlight to enter and then prevent heat from leaving the atmosphere.These gases include carbon dioxide(CO2), methane(CH 4), nitrous oxide(N20),and water vapor. Human activities—especially burning fossil fuels—are increasing the concentrations of many of these gases,amplifying the natural greenhouse effect. Image courtesy of the Marian Koshland Science Museum of the National Academy of Sciences : a Early Understanding of GreenhouseGases In 1824, French physicist Joseph Fourier(top)was the first to suggest that the Earth's atmosphere might act as an insulator of some kind—the first proposal of what was later called the greenhouse effect. In the 1850s, Irish- born physicist John Tyndall (middle)was the first to demonstrateY the greenhouse effect by showing that water vapor and other atmospheric gases absorbed Earth's radiant heat. In 1896,Swedish scientist Svante Arrhenius(bottom)was the first to calculate the warming power of excess carbon dioxide(CO2). From his calculations, Arrhenius predicted that if human activities increased CO2 levels in the atmosphere,a warming trend would result. 5 tiU 2 \y yyQ r°y� Q Q Fossil Fuel Emissions Exchange of COs Volcanic 41! Eruptions €, Weathering 111111 of Rocks N . Waste and Decay of Dead Organisms Fossil Fuels, Limestone Coal,Oil,and Gas (Calcium Carbonate) Marine Deposits The Carbon Cycle Carbon is continually exchanged between the atmosphere,ocean, biosphere,and land on a variety of timescales. In the short term,CO2 is exchanged continuously among plants,trees,animals,and the air through respiration and photosynthesis,and between the ocean and the atmosphere through gas exchange.Other parts of the carbon cycle,such as the weathering of rocks and the formation of fossil fuels,are much slower pro- cesses occurring over many centuries.For example, most of the world's oil reserves were formed when the remains of plants and animals were buried in sediment at the bottom of shallow seas hundreds of millions of years ago,and then exposed to heat and pressure over many millions of years.A small amount of this carbon is released naturally back into the atmosphere each year by volcanoes,completing the long-term carbon cycle. Human activities,espe- cially the digging up and burning of coal,oil,and natural gas for energy,are disrupting the natural carbon cycle by releasing large amounts of"fossil"carbon over a relatively short time period.Source: National Research Council How do we know that humans are causing greenhouse gas concentrations to increase? Discerning the human influence on greenhouse tional CO2 began to be released into the atmosphere gas concentrations is challenging because many much more rapidly than in the natural carbon cycle. greenhouse gases occur naturally in Earth's atmo- Other human activities,such as cement production sphere. Carbon dioxide(CO2)is produced and con- and cutting down and burning of forests(deforesta- sumed in many natural processes that are part of the tion), also add CO2 to the atmosphere. carbon cycle(see Figure 4). However, once humans Until the 1950s, many scientists thought the began digging up long-buried forms of carbon such oceans would absorb most of the excess CO2 as coal and oil and burning them for energy,addi- released by human activities.Then a series of 6 Concentrations of Greenhouse Gases from 0 to 2005 400 2000 Scripps Institution of Oceanography 1800 0 380 NOAA Earth System Research Laboratory _ Carbon oioxode (CO,) ` - Methane (CH,) 1600 c a zo 360 Q 350- Nitrous Oxide (N,O) 0 U ^ � 1400 a p" a C5 H 340 a 1200 v 0 300 1000 Am R c 320 800 1960 1970 1980 1990 2000 2010 250 600 0 500 1000 1500 2000 YEAR Year Measurements of Atmospheric Carbon Dioxide Greenhouse Gas Concentrations for 2,000 Years The"Keeling Curve" is a set of careful measurements Analysis of air bubbles trapped in Antarctic ice cores of atmospheric CO2 that Charles David Keeling show that,along with carbon dioxide,atmospheric began collecting in 1958.The data show a steady concentrations of methane(CH4)and nitrous oxide annual increase in CO2 plus a small up-and-down (N20)were relatively constant until they started to rise sawtooth pattern each year that reflects seasonal in the Industrial era.Atmospheric concentration units changes in plant activity(plants take up CO2 during indicate the number of molecules of the greenhouse spring and summer in the Northern Hemisphere, gas per million molecules of air for carbon dioxide where most of the planet's land mass and land and nitrous oxide,and per billion molecules of air for ecosystems reside,and release it in fall and winter). methane.Image courtesy:U.S.Global Climate Research Source: National Research Council,2010a Program scientific papers were published that examined the the Industrial Revolution, atmospheric CO2 dynamics of carbon dioxide exchange between concentrations were steady and then began to rise the ocean and atmosphere, including a paper by sharply beginning in the late 1800s(Figure 6). oceanographer Roger Revelle and Hans Seuss in Today,atmospheric CO2 concentrations exceed 390 1957 and another by Bert Bolin and Erik Eriksson parts per million—nearly 40%higher than in 1959.This work led scientists to the hypothesis preindustrial levels,and, according to ice core data, that the oceans could not absorb all of the CO2 higher than at any point in the past 800,000 years being emitted.To test this hypothesis, Revelle's (see Figure 14, p.18). colleague Charles David Keeling began collecting Human activities have increased the atmospheric air samples at the Mauna Loa Observatory in Hawaii concentrations of other important greenhouse to track changes in CO2 concentrations.Today, gases as well. Methane, which is produced by such measurements are made at many sites around the burning of fossil fuels, the raising of livestock, the world.The data reveal a steady increase in the decay of landfill wastes, the production and atmospheric CO2(Figure 5). transport of natural gas, and other activities, To determine how CO2 concentrations varied increased sharply through the 1980s before prior to such modern measurements, scientists have starting to level off at about two-and-a-half studied the composition of air bubbles trapped in times its preindustrial level (Figure 6). Nitrous ice cores extracted from Greenland and Antarctica. oxide has increased by roughly 15%since 1750 These data show that,for at least 2,000 years before (Figure 6), mainly as a result of agricultural 7 2 u 0 g -2 r' -4 -6 8 u 8 1960 1970 1980 1990 2000 2010 s ^ Year Fossil fuel Q^ 6 6 and cement Land Sink m g� u 4 E" 4 Land-use n d c ,2 change 2 .E 2 a 2 0 Lil 0 01960 1970 1980 1990 2000 20100 1960 1970 1980 1990 2000 2010 Year Year Emissions -, Atmospheric s Concentration -6 kO 1970 1980 1990 2000 2010 Growth Y_ Ocean Sink Emissions Exceed Nature's CO2 Drain Emissions of CO2 due to fossil fuel burning and cement manufacture are increasing,while the capacity of"sinks"that take up CO2 for example, plants on land and in the ocean—are decreasing.Atmospheric CO2 is increasing as a result. Source: National Research Council,2011 a fertilizer use, but also from fossil fuel burning and analyses show that about 45%of the CO2 emitted certain industrial processes. Certain industrial by human activities remains in the atmosphere. chemicals, such as chlorofluorocarbons(CFCs), just as a sink will fill up if water is entering it faster act as potent greenhouse gases and are long-lived than it can drain, human production of CO2 is in the atmosphere. Because CFCs do not have outstripping Earth's natural ability to remove it natural sources, their increases can be attributed from the air.As a result, atmospheric CO2 levels are unambiguously to human activities. increasing (see Figure 7)and will remain elevated In addition to direct measurements of CO2 for many centuries. Furthermore, a forensic-style concentrations in the atmosphere, scientists have analysis of the CO2 in the atmosphere reveals the amassed detailed records of how much coal, oil, chemical "fingerprint" of carbon from fossil fuels and natural gas is burned each year.They also (see Box 2).Together, these lines of evidence prove estimate how much CO2 is being absorbed, on conclusively that the elevated CO2 concentration in average, by the oceans and the land surface. These the atmosphere is the result of human activities. • Clues from the "fingerprint" of carbon dioxide. In a process that takes place over millions of years, carbon from the decay of plants and animals is stored deep in the Earth's crust in the form of coal, oil,and natural gas (see Figure 4). Because this "fossil" carbon is so old, it contains very little of the radioisotope carbon-14—a form of the carbon that decays naturally over long time periods.When scientists measure carbon-14 levels in the atmosphere, they find that it is much lower than the levels in living ecosystems, indicating that there is an abundance of"old" carbon.While a small fraction of this old carbon can be attributed to volcanic eruptions,the overwhelming majority comes from the burning of fossil fuels.Average CO2 emissions from volcanoes are about 200 million tons per year,while humans are emitting an estimated 36 billion tons of CO2 each year, 80-85% of which are from fossil fuels. I li j How much are human activities heating Earth? Greenhouse gases are referred to '' '"r ' u a cooling effect because they scatter a as"forcing agents" because of portion of incoming sunlight back into their ability to change the planet's space(see Box 3). Human activities, energy balance.A forcing agent especially the burning of fossil fuels, can "push" Earth's temperature -�- have increased the number of up or down. Greenhouse gases `is aerosol particles in the atmosphere, differ in their forcing power. especially over and around major For example, a single methane urban and industrial areas. molecule has about 25 times Changes in land use and land the warming power of a single cover are another way that human CO2 molecule. However, CO2 has a activities are influencing Earth's climate. much larger overall warming effect than Deforestation is responsible for 10%to 20%of methane because it is much more abundant and the excess CO2 emitted to the atmosphere each stays in the atmosphere for much longer periods year, and, as has already been discussed, agriculture of time. Scientists can calculate the forcing power contributes nitrous oxide and methane. Changes in of greenhouse gases based on the changes in their land use and land cover also modify the reflectivity concentrations over time and on physically based of Earth's surface; the more reflective a surface, the calculations of how they transfer energy through the more sunlight is sent back into space. Cropland is atmosphere. generally more reflective than an undisturbed forest, Some forcing agents push Earth's energy balance while urban areas often reflect less energy than toward cooling, offsetting some of the heating undisturbed land. Globally, human land use changes associated with greenhouse gases. For example, are estimated to have a slight cooling effect. some aerosols—which are tiny liquid or solid When all human and natural forcing agents are particles suspended in the atmosphere, such as those considered together, scientists have calculated that that make up most of the visible air pollution—have the net climate forcing between 1750 and 2005 is • Warming and Cooling Effects of Aerosols Aerosols are tiny liquid or solid particles suspended in the atmosphere that come from a number of human activities, such as fossil fuel combustion,as well as natural processes, such as dust storms,volcanic eruptions,and sea spray emissions from the ocean. Most of our visible air pollution is made up of aerosols. Most aerosols have a cooling effect, because they scatter a portion of incoming sunlight back into space,although some particles,such as dust and soot, actually absorb some solar energy and thus act as warming agents. Many aerosols also enhance the reflection of sunlight back to space by making clouds brighter,which results in additional cooling. Many nations,states,and communities have taken action to reduce the concentrations of certain air pollutants such as the sulfate aerosols responsible for acid rain. Unlike most of the greenhouse gases released by human activities,aerosols only remain in the atmosphere for a short time—typically a few weeks. 9 .- Miami, Cooling Influences Warming Influences Human Activities' •' • Long-lived N,O Nitrous greenhouse Oxide gases Halocarbons Stratospheric Methane pushing Earth toward warming (Figure 8).The extra Ozone Tropospheric (-o.oe) energy is about 1.6 Watts per square meter of Earth's Stratospheric surface.When multiplied by the surface area of water vapor Surface Soot(bl2ckcarbon) Earth, this energy represents more than 800 trillion reflectivity ; Land use ori snow Watts(Terawatts)—on a per year basis, that's about Direct 50 times the amount of power produced by all the m effect F y cloud power plants of the world combined!This extra X reflective energy is being added to Earth's climate system effect every second of every day. Total natural influences The total amount of warming that will occur in (solar output) response to a climate forcing is determined by a 'Total net (human activities) variety of feedbacks,which either amplify or dampen z o z the initial warming. For example, as Earth warms, polar snow and ice melt,allowing the darker colored Energy(Watts/ml) land and oceans to absorb more heat--causing Earth to become even warmer,which leads to more snow Warming and Cooling Influences on Earth and ice melt,and so on(see Figure 9).Another impor- Since 1750 The warming and cooling influences tant feedback involves water vapor.The amount of (measured in Watts per square meter)of various cli- water vapor in the atmosphere increases as the ocean mate forcing agents during the Industrial Age(from surface and the lower atmosphere warm up;warm- about 1750)from human and natural sources has been calculated. Human forcing agents include increases in Ing of 1°C(1.8°F)increases water vapor by about greenhouse gases and aerosols,and changes in land 7%. Because water vapor is also a greenhouse gas, use.Major volcanic eruptions produce a temporary this increase causes additional warming. Feedbacks cooling effect,but the Sun is the only major natural factor with a long-term effect on climate.The net ef- that reinforce the initial climate forcing are referred fect of human activities is a strong warming influence to in the scientific community as positive, or ampli- of more than 1.6 Watts per square meter.Source:Na- f In feedbacks. tional Research Council,2010a(Depiction courtesy U.S. y g' Global Climate Research Program) There is an inherent time lag in the warming that is caused by a given climate forcing.This lag occurs TEMPERATURES RISE because it takes time for parts of Earth's climate systems—especially the massive oceans—to warm or cool. Even if we could hold all human-produced _.h forcing agents at present-day values, Earth would "R continue to warm well beyond the 1.4°F already ob- served because of human emissions to date. Climate Feedback Loops The amount of warming ARCTIC SEA that occurs because of increased greenhouse gas AS REFLECTIVE _ ICE MELTS emissions depends in part on feedback loops. ICE DISAPPEARS, - r--' _ Positive(amplifying)feedback loops increase the DARKER OCEAN net temperature Change from a given forcing,while WATER ABSORBS HEAT negative(damping)feedbacks offset some of the MHEAgym,-� ._--.,_ temperature change associated with a climate forcing. The melting of Arctic sea ice is an example of a positive feedback loop.As the ice melts, less sunlight is reflected back to space and more is absorbed into the dark ocean,causing further warming and further melting of ice.Source: National Research Council,2011 d 10 t- M it A.d I �' � {` / How do we kno eir�'`` ` warming trend M g isn't caused by the Sun? Apother way to test a scientific theory is to in- the Sun's output has not shown a net increase dur- vestigate alternative explanations. Because ing the past 30 years(Figure 10)and thus cannot be the Sun's output has a strong influence on Earth's responsible for the warming during that period. temperature, scientists have examined records of Prior to the satellite era, solar energy output had solar activity to determine if changes in solar output to be estimated by more indirect methods, such as might be responsible for the observed global warm- records of the number of sunspots observed each ing trend.The most direct measurements of solar year, which is an indicator of solar activity.These output are satellite readings,which have been avail- indirect methods suggest there was a slight increase able since 1979.These satellite records show that in solar energy reaching Earth during the first few Irr dionce Composite Measures of the Sun's Energy 1363 Satellite measurements of the Sun's 1362 energy incident on Earth,available since all 1979,show no net increase in solar 1361 forcing during the past 30 years.They 3 3t 1360 show only small periodic variations 1359 associated with the 11-year solar cycle. 1358 Source: National Research Council,2010a 1357 1980 1985 1990 1995 2000 2005 Global lower stratospheric anomalies from Jan 1958 to Mar 2010 1.5 Warming Patterns in the Layers of $ 1.0— StratOSphe IC cooling trend the Atmosphere Data from weather o.s balloons and satellites show a warming r trend in the troposphere,the lower 3 0.0 layer of the atmosphere,which extends 7,,-05 up about 10 miles(lower graph),and Ea cooling trend in the stratosphere, -10 Agung EI Chichon Pinatubo -- which is the layer immediately above -1.5 the troposphere(upper graph).This 1960 1970 1980 Year 1990 2000 2010 is exactly the pattern expected from Global lower tropospheric and surface anomalies from Jan 1958 to Mar 2010 increased greenhouse gases,which trap 0.8 energy closer to the Earth's surface. 0.6Tropospheric warming trend - Source: National Research Council,2010a m 0.4 r oz o.o U -0.2 r E -0.4 o -06- -0.8 06-0.8 1960 1970 1980 1990 2000 2010 Year 6r_ 11 decades of the 20th century.This increase may have atmosphere since the late 1970s. Both of these data contributed to global temperature increases during sets have been heavily scrutinized, and both show a that period, but does not explain warming in the warming trend in the lower layer of the atmosphere latter part of the century. (the troposphere)and a cooling trend in the Further evidence that current warming is not upper layer(the stratosphere)(Figure 11).This is a result of solar changes can be found in the exactly the vertical pattern of temperature changes temperature trends in the different layers of the expected from increased greenhouse gases, atmosphere.These data come from two sources: which trap energy closer to the Earth's surface. If weather balloons, which have been launched an increase in solar output were responsible for twice daily from hundreds of sites worldwide the recent warming trend, the vertical pattern of since the late 1950s, and satellites, which have warming would be more uniform through the monitored the temperature of different layers of the layers of the atmosphere. How do we know that the current warming trend is not caused by natural cycles? Detecting climate trends is temperatures tend to be higher complicated by the fact during EI Nino periods, such as that there are many natural 1998, and lower during La variations in temperature, Nina years, such as 2008. precipitation, and other However, these up-and- climate variables.These - --'_' down fluctuations are natural variations are smaller than the 20th cen- caused by many different tury warming trend; 2008 processes that can occur was still quite a warm year across a wide range of in the long-term record. timescales—from a particularly Natural climate variations can warm summer or snowy winter also be forced by slow changes in to changes over many millions of the Earth's orbit around the Sun that years. affect the solar energy received by Earth, as Among the most well-known short-term cli- is the case with the Ice Age cycle(see pp. 18-19) matic fluctuations are EI Nino and La Nina,which or by short-term changes in the amount of volca- are periods of natural warming and cooling in the nic aerosols in the atmosphere. Major eruptions, tropical Pacific Ocean. Strong EI Nino and La Nina like that of Mount Pinatubo in 1991, spew huge events are associated with significant year-to-year amounts of particles into the stratosphere that i changes in temperature and rainfall patterns across cool Earth. However, surface temperatures typically many parts of the planet, including the United rebound in 2-5 years as the particles settle out of States.These events have been linked to a number the atmosphere.The short-term cooling effects of of extreme weather events, such as the 1992 flood- several large volcanic eruptions can be seen in the ing in midwestern states and the severe droughts 20th century temperature record, as can the global in southeastern states in 2006 and 2007. Globally, temperature variations associated with several 12 strong EI Nino and La Nina events, but an overall warming trend is still evident(Figure 12). In order to put EI Nino and La Nina events and f' f; other short-term natural fluctuations into perspec- tive, climate scientists examine trends over several decades or longer when assessing the human influ- ence on the climate system. Based on a rigorous as- sessment of available temperature records, climate forcing estimates, and sources of natural climate variability, scientists have concluded that there is a more than 90%chance that most of the observed global warming trend over the past 50 to 60 years can be attributed to emissions from the burning of i fossil fuels and other human activities. Such statements that attribute climate change to human activities also rely on information from _ i _ Short-term Temperature Effects 2.0 of Natural Climate Variations Natural factors,such as volcanic 1.5 - -- Strong EI Nino eruptions and EI Nino and La Nina events,can cause average global 1.0 temperatures to vary from one year - Wtubo to the next, but cannot explain the long-term warming trend over the 0.s past 60 years. Image courtesy of the ption Marian Koshland Science Museum E Mt.EuPina r 0.0 ..- --- - -- ------ �_ Prolo ed La Nina Volcanic Eruption- -0.5 L____ Mt.Ague ng 1900 1920 1940 1960 1980 2000 Years Globally averaged surface air temperature ANN Model Runs With and Without Human Influences Model Observations U Only natural influences simulations of 20th-century surface 1.2 temperatures more closely match Natural and human influences observed temperature when both rn natural and human influences are 0 0.8 included in the simulations.The , _rn black line shows an estimate of E 0.4 observed surface temperatures o changes.The blue line shows results U) from models that only include 01 0.0 r natural forcings(solar activity and E volcanoes).The red-shaded regions cid 0.4 show results from models that include both natural and human forcings.Source: Meehl et al,2011 1860 1890 1920 1950 1980 13 r ,9 , Perhaps the most dramatic example of natural climate variability over long time periods is the Ice Age cycle. Detailed analyses of ocean sediments, ice cores, and other data show that for at least 800,000 years, and probably for the past 4 to 5 million years,the Earth has gone through extended periods when temperatures were much lower than today and thick blankets of ice covered large areas of the Northern Hemisphere.These long cold spells,which typically lasted for around 100,000 years,were interrupted by shorter warm "interglacial" periods, including the past 10,000 years (Figure 14). Through a convergence of theory, observations, and modeling, scientists have deduced that the ice ages are caused by slight recurring variations in Earth's orbit that alter the amount and seasonal distribution of solar energy reaching the Northern Hemisphere.These relatively small changes in solar energy are reinforced over thousands of years by gradual changes in Earth's ice cover (the cryosphere) and ecosystems (the biosphere), eventually leading to large changes in global CO2 concentration today, 400 800,000 Years of Temperature _ 390 and Carbon Dioxide Records The Ice Age Cycle as measured in air 380 As ice core records from Vostok, 360 Antarctica, show,the tempera- ture near the South Pole has 340 2 varied by as much as 20°F(11°C) 320 a during the past 800,000 years. 300 C The cyclical pattern of tempera- 300 variations constitutes the ice 280 a age/interglacial cycles. During 260 o these cycles,changes in carbon dioxide concentrations(in red) 240 O track closely with changes in 220 temperature(in blue),with CO2 lagging behind temperature 200 changes. Because it takes a while 180 for snow to compress into ice,ice 6 core data are not yet available V 4 much beyond the 18th century at 2 most locations. However,atmo- s o spheric carbon dioxide levels,as -2 measured in air,are higher today -4than at any time during the past 6 800,000 years.Source: National Research Council,2010a a -8 F - -VOV 10 -12 800,000 700,000 600,000 500,000 400,000 300,000 200,000 100,000 0 800,000 Years Ago to Recent Times(late 18th century) R11. k .. temperature.The average global temperature change during an ice age cycle,which occur over about 100,000 years, is on the order of 9°F± 2°F (5°C ± 0 The data show that in past ice age cycles, changes in temperature have led—that is, started prior to—changes in CO2. This is because the changes in temperature induced by changes .t in Earth's orbit around the Sun lead to gradual changes in the biosphere and the carbon cycle, and thus CO2, reinforcing the initial temperature trend. In contrast, the relatively rapid release of CO2 and other greenhouse gases since the start of the Industrial Revolution from the burning of fossil fuel has, in essence, reversed the pattern: the _ additional CO2 is acting as a climate forcing,with temperatures increasing afterward. Y_ The ice age cycles nicely illustrate The U.S.Geological Survey National Ice Core Lab how climate forcing and feedback stores ice cores samples taken from polar ice caps effects can alter Earth's temperature, but and mountain glaciers. Ice cores provide clues there is also direct evidence from past about changes in Earth's climate and atmosphere going back hundreds of thousands of years. climates that large releases of carbon dioxide have caused global warming. One of the largest known events of this type is called the Paleocene-Eocene Thermal Maximum, or PETM, which occurred about 55 million years ago, when Earth's climate was much warmer than today. Chemical indicators point to a huge release of carbon dioxide that warmed Earth by another 9°F and caused widespread ocean acidification. These climatic changes were accompanied by massive ecosystem changes, such as the emergence of many new types of mammals on land and the extinction of many bottom- dwelling species in the oceans. 19 P Ni yy.. a no i 2 � � h, 7 +y €, l ,\ .'III i '+�� .L�,. �c`•y� l r iMt d 1 � n order to respond Fortunately, scientists have made great strides in effectively predicting the amount of temperature change that e y to the risks g posed by future climate can be expected for different amounts of future change, decision makers greenhouse gas emissions and in understanding need information on the how increments of globally averaged types and severity of temperatures—increases of 10C, 2°C, 3°C and so forth—relate to a wide range of impacts. impacts that might Many of these projected impacts pose serious be expected. risks to human societies and things people care about, including water resources, coastlines, infrastructure, human health, food security, and land and ocean ecosystems. 20 ANO b ✓ 1.:. L 11i_ How do scientists project future climate change? The biggest factor in determining future global Each model uses a slightly different set of mathe- warming is projecting future emissions of CO2 matical equations to represent how the atmosphere, and other greenhouse gases—which in turn depend oceans, and other parts of the climate system inter- on how people will produce and use energy,what act with each other and evolve over time. Models • national and international policies might be imple- are routinely compared with one another and tested mented to control emissions, and what new tech- against observations to evaluate the accuracy and nologies might become available. Scientists try to robustness of model predictions. account for these uncertainties by developing differ- The most comprehensive suite of modeling ex- ent scenarios of how future emissions—and hence periments to project global climate changes was climate forcing—will evolve. Each of these scenarios completed in 2005.1 It included 23 different models is based on estimates of how different socioeco- from groups around the world, each of which used nomic, technological, and policy factors will change the same set of greenhouse gas emissions scenarios. over time, including population growth, economic Figure 19 shows projected global temperature activity, energy-conservation practices, energy tech- changes associated with high, medium-high, and nologies, and land use. low future emissions(and also the "committed" Scientists use climate models(see Box 4, p.14) to project how the climate system will respond to 'The modeling experiments were part of the World Cli- different scenarios of future greenhouse gas concen- mate Research Programme's Coupled Model Intercom- parison Project phase 3(CMIP3)in support of the Inter- trations.Typically, many different models are used, governmental Panel on Climate Change(IPPC)Fourth each developed by a different modeling team. Assessment Report. — High emissions(A2) Projected temperature change for three 4.0 _ Medium-high emissions(A1 B) emissions scenarios Models project global — Low emissions(61) mean temperature change during the 21st ' o 3 0 Constant composition century for different scenarios of future Cn commitment run emissions—high (red), medium-high(green) — 20th century and low(blue)—each of which is based on E 2.0 different assumptions of future population C° growth,economic development, life-style 3 choices,technological change,and avail- 1.0 ability of energy alternatives.Also shown are the results from "constant concentrations N 0.0 17 commitment"runs,which assume that atmo- a 21 17 12 spheric concentrations of greenhouse gases 21 16 10 remain constant after the year 2000. Each 1.0 23 16 solid line represents the average of model ' runs from different modeling using the same 1900 2000 2100 2200 2300 scenario,and the shaded areas provide a measure of the spread (one standard devia- Year tion) between the temperature changes projected by the different models.Source: National Research Council,2010a 21 warming—warming that will occur as a result of 2100, relative to the late 20th century, ranging from greenhouse gases that have already been emitted). less than 2°F(1.1°C)for the low emissions scenario Continued warming is projected for all three future to more than 11°F(6.1'C)for the high emissions emission scenarios, but sharp differences in global scenario.These results show that human decisions average temperature are clearly evident by the end can have a very large influence on the magnitude of of the century,with a total temperature increase in future climate change. How will temperatures be affected? Local temperatures vary widely from day to day, ing amount of global average warming and then week to week, and season to season, but how scaled to show what pattern of warming would be will they be affected on average?Climate modelers expected.Warming is greatest in the high latitudes have begun to assess how much of a rise in average of the Northern Hemisphere and is significantly temperature might be expected in different regions larger over land than over ocean. (Figure 20).The local warmings at each point As average temperatures continue to rise, the on the map are first divided by the correspond- number of days with a heat index above 100°F 2011-2030 2046-2065 2080-2099 C Lower ( ► Emissions G 'gam. Scenario � �� - v J y AIB 'A �� V Middle-Level Emissions diiC_ ScenarioG' .+'I r A2 +► g° Higher �,. Emissions ti Scenario 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 CC) Temperature Increase Projected warming for three emissions scenarios Models project the geographical pattern of annual average surface air temperature changes at three future time periods(relative to the average temperatures for the period 1961-1990)for three different scenarios of emissions.The projected warming by the end of the 21 st century is less extreme in the B1 scenario,which assumes smaller greenhouse gas emissions,than in either the Al B scenario or the A2"business as usual"scenario.Source: National Research Council 2010a 22 Recent Past, 1961-1979 f y Projections of Hotter Days Model projections sug- gest that,relative to the 1960s and 1970s,the number of days with a heat index above 100°F will increase markedly across the United States. Image courtesy U.S. r Global Climate Research Program Lower Emissions Scenario91,2080-2099 ,.: (the heat index combines temperature and humid- ity to determine how hot it feels) is projected to increase throughout this century(Figure 21). By the end of the century, the center of the United States is expected to experience 60 to 90 ad- ditional days per year in which the heat index is Higher Emissions Scenario91,2080-2099 more than 100°F. Heat waves also are expected • to last longer as the average global temperature increases. It follows that as global temperatures rise, the risk of heat-related illness and deaths also should rise. Similarly, there is considerable con- fidence that cold extremes will decrease, as will cold-related deaths. The ratio of record high tem- peratures to record low temperatures, currently Number of days with heat index>100T 2 to 1, is projected to increase to 20 to 1 by mid- I --I— <10 20 30 45 60 75 90 105 >120 century and 50 to 1 by the end of the century for a mid-range emissions scenario. How is precipitation expected to change? Global warming is ex- Using the same general • pected to intensify approach as for tempera- regional contrasts in precipi- tures,scientists can project tation that already exist: dry regional and seasonal per- areas are expected to get R=< centage change in precipita- even drier, and wet areas tion expected for each 1°C even wetter.This is because (1.8°F)of global warming warmer temperatures tend (Figure 22).The results show to increase evaporation from that the subtropics, where oceans, lakes, plants, and most of the world's deserts soil,which, according to both theory and observa- are concentrated, are likely to see 5-10%reductions tions,will boost the amount of water vapor in the in precipitation for each degree of global warming. atmosphere by about 7%per VC(1.81)of warm- In contrast, subpolar and polar regions are expected ing.Although enhanced evaporation provides more to see increased precipitation, especially during win- atmospheric moisture for rain and snow in some ter.The overall pattern of change in the continental downwind areas, it also dries out the land surface, United States is somewhat complicated, as it lies which exacerbates the impacts of drought in some between the drying subtropics of Mexico and the regions. Caribbean and the moistening subpolar regions of 23 WINTER SUMMER (Dec-Jan-Feb) (June-Jul-Aug) %change in precipitation %change in precipitation 30 o O r o 20 50 e 15 10 5 2 0 0 -2 F, 5 -10 o� 1. -15 -50 - _50- _ -20 -30 -150 -100 -50 0 50 100 150 -150 -100 -50 0 50 100 150 Precipitation Patterns per Degree Warming Higher temperatures increase evaporation from oceans, lakes, plants,and soil, putting more water vapor in the atmosphere and, in turn, producing more rain and snow in some areas.However,increased evaporation also dries out the land surface,which reduces precipitation in some regions. This figure shows the projected percentage change per 1°C(1.8°F)of global warming for winter(December-Febru- ary, left)and summer(June-August, right). Blue areas show where more precipitation is predicted,and red areas show where less precipitation is predicted.White areas show regions where changes are uncertain at present, be- cause there is not enough agreement among the models used on whether there will be more or less precipitation in those regions.Source: National Research Council,2011 b Canada. Most models suggest increased drying in throughout most of the United States, except for the southwestern United States. parts of the Northwest and Northeast, with particu- Observations in many parts of the world show larly sharp drops in the Southwest.A decrease in a statistically significant increase in the intensity of runoff of 5-10% per degree of warming is expected heavy rainstorms. Computer models indicate that in some river basins, including the Arkansas and the this trend will continue as Earth warms, even in Rio Grande(Figure 23).This decrease would be due subtropical regions where overall precipitation will mainly to increased evaporation because of higher decrease. In those regions, the projections show an temperatures,which will not be offset by changes increase in dry days between rainstorms with the av- in precipitation. Globally, streamflow in many tem- erage rainfall over seasons going down. In general, perate river basins outside Eurasia is likely to de- extreme rainstorms are likely to intensify by crease, especially in arid and semiarid regions. 5-10%for each 1°C(1.8°F)of global Rising temperatures and increased warming, with the greatest intensi- evaporation and drought can also be fication in the tropics,where rain expected to boost the risk of fire is heaviest. in some regions. In general,for- Changes in precipitation ests that are already fire-prone, will affect annual streamflow, such as the evergreen forests of which is roughly equal to the r =s the western United States and 9 Y Q _ amount of runoff—the water - _ , Canada,are likely to become from snow or rain that flows .. even more vulnerable to fire as into rivers and creeks. Global temperatures rise.The average climate models indicate that area burned by wildfire per year in future runoff is likely to decrease parts of the western United States is 24 rt ' -20 -15 -10 -5 0 5 10 15 20 change in runoff per degree warming (relative to 1971-2001) • Changes in Runoff per Degree Warming Enhanced evaporation caused by warming is projected to decrease the z amount of runoff—the water flowing into rivers and creeks—in many parts of the United States. Runoff is a key index of the availability of fresh water.The figure shows the percent median change in runoff per degree of global warming relative to the period from 1971 to 2000.Red areas show where runoff is expected to decrease,green where it will increase. Source: National Research Council,2011 a LU expected to increase annually by two to four times _ per degree of warming(Figure 24).At the same time, B 241'GLU areas dominated by shrubs and grasses,such as parts of the Southwest, may experience a reduction in fire over time as warmer temperatures cause shrubs and grasses to die out. In this case,the potential societal benefits of fewer fires would be countered by the loss D of existing ecosystems. 73% At ♦ K 74% Increased Risk of Fire Rising temperatures and in- creased evaporation are expected to increase the risk of fire in many regions of the West.This figure shows the percent increase in burned areas in the West for a 1°C increase in global average temperatures relative to the median area burned during 1950-2003. For example, fire damage in the northern Rocky Mountain forests, marked by region B,is expected to more than double annually for each 1°C(1.81)increase in global average temperatures.Source: National Research Council,2011 a 25 How will sea ice and snow be affected? As global warming continues, the banned the use of ozone-depleting planet's many forms of ice are chemicals. Still, Antarctic sea ice decreasing in extent,thickness, may decrease less rapidly than and duration. Models indicate Arctic ice, in part because the that seasonally ice-free condi- Southern Ocean stores heat tions in the Arctic Ocean are at greater depths than the likely to occur before the end Arctic Ocean, where the of this century and suggest heat can't melt ice as easily. about a 25%loss in Septem- _ In many areas of the ber sea-ice extent for each globe, snow cover is expect- VC(1.8°F)in global warming. ed to diminish, with snowpack In contrast to the Arctic, sea building later in the cold season ice surrounding Antarctica has, on and melting earlier in the spring. average, expanded during the past According to one sensitivity analysis, several decades.This increase may be linked each VC(1.8°F)of local warming may lead to the stratospheric "ozone hole" over the Antarc- to an average 20% reduction in local snowpack in tic, which developed because of the use of ozone- the western United States. Snowpack has impor- depleting chemicals in refrigerants and spray cans. tant implications for drinking water supply and The ozone hole allows more damaging UV light to hydropower production. In places such as Siberia, get to the lower atmosphere and, in the Antarctic, parts of Greenland, and Antarctica, where tem- may have also resulted in lower temperatures as peratures are low enough to support snow over more heat escapes to space. However, this effect is long periods, the amount of snowfall may increase expected to wane as ozone returns to normal levels even as the season shortens, because the increased by later this century, due in part to the success of amount of water vapor associated with warmer the Montreal Protocol, an international treaty that temperatures may enhance snowfall. How will coastlines be affected? Some of Earth's most densely populated regions Quantifying the future threat posed to particular lie at low elevation, making rising sea level coastlines by rising seas and floods is challeng- a cause for concern. Sea-level rise is projected ing. Many nonclimatic factors are involved, such to continue for centuries in response to human- as where people choose to build homes, and the caused increases in greenhouse gases, with an risks will vary greatly from one location to the next. estimated 0.5-1.0 meter(20-39 inches) of mean Moreover, infrastructure damage is often triggered sea-level rise by 2100. However, there is evidence by extreme events, for example hurricanes and that sea-level rise could be greater than expected earthquakes, rather than gradual change. However, due to melting of sea ice. Recent studies have there are some clear "hot spots," particularly in shown more rapid than expected melting from large urban areas on coastal deltas, including those glaciers and ice sheets. Observed sea-level rise has of the Mississippi, Nile, Ganges, and Mekong rivers. been near the top of the range of projections that If average sea level rises by 0.5 meters(20 inches) were made in 1990(Figure 25). relative to a 1990 baseline, coastal flooding could 26 8 Satellite Observations 4 2 MCC Proje*m U M N _2 Tide Gauges -4 1970 1975 1980 1985 1990 1995 2000 2005 2010 Year Comparison of Projected and Observed Sea-Level Rise Observed sea-level change since 1990 has been near the top of the range projected by the Intergov- ernmental Panel on Climate Change Third Assessment Report,published in 1990(gray-shaded area).The red line shows data derived from tide gauges from 1970 to 2003.The blue line shows satellite observations of sea- level change.Source: National Research Council,2011 a affect 5 million to 200 million people worldwide. Up where reductions in sea ice and melting permafrost to 4 million people could be permanently displaced, allow waves to batter and erode the shoreline. and erosion could claim more than 250,000 square Coastal erosion effects at 1.0 meter of sea-level kilometers of wetland and dryland(98,000 square rise would be much greater, threatening many miles, an area the size of Oregon). Relocations are parts of the U.S. coastline (Figure 26). already occurring in towns along the coast of Alaska, municipality : • • • susceptible • 6-meter rise 34"D %area susceptible • 1-meter rise 7"o 6-meter rise Washington Norfolk IL 0 •• Projected Effects of Sea-Level Savannah Rise on the U.S. East and Gulf New Orleans Coasts If sea level were to rise as 9911" much as 1 meter(3.3-feet),the • • areas in pink would be susceptible Jacksonville to coastal flooding.With a 6-me- ter(19.8-foot)rise in sea level, Or areas shown in red would also be susceptible.The pie charts show Tampa the percentage area of some cities _ that are potentially susceptible at • 1-meter and 6-meter sea-level rise. Source: National Research Council, 2010a 27 How will ecosystems be affected? Nether marine or terrestrial, all organisms The American pika attempt to acclimate to a changing environ- is a cold-adapted species that is ment or else move to a more favorable location— being isolated but climate change threatens to push some species on mountaintop beyond their ability to adapt or move. Special "islands" by rising temperatures. stress is being placed on cold-adapted species on image courtesy mountain tops and at high latitudes. Shifts in the of J. R. Douglass, timing of the seasons and life-cycle events such as ' Yellowstone w National Park. blooming, breeding, and hatching are causing mis- matches between species that disrupt patterns of feeding, pollination, and other key aspects of foodlar ;. webs.The ability of species to move and adapt also are hampered by human infrastructural barriers (e.g., roads), land use, and competition or interac- 80°N �- tion with other species. In the ocean, circulation changes will be a key driver of ecosystem impacts. Satellite data show that 40°N g� r warm surface waters are mixing less with cooler, deeper waters, separating near-surface marine life from the nutrients below and ultimately reducing 0° 1 the amount of phytoplankton, which forms the base of the ocean food web(Figure 27). Climate change will exacerbate this problem in the tropics 40°5 0 and subtropics. However, in temperate and polar waters, vertical mixing of waters could increase, especially with expected losses in sea ice.At the 80°S same time, ocean warming will continue to push the ranges of many marine species toward the poles. Change in Primary Production(PP) Changing ocean chemistry can result in other -48 -24 -12 -6 -3 -1.5 0 1.5 3 6 12 24 48 impacts—warmer waters could lead to a decline in subsurface oxygen, boosting the risk of"dead Effects on the Ocean Food Web The growth rate zones,"where species high on the food chain are of marine phytoplankton,which form the base of largely absent because of a lack of oxygen. Ocean the ocean food web, is likely to be reduced over time acidification, brought on as the oceans take in more because of higher ocean surface temperatures.This creates a greater distance between warmer surface of the excess CO2 will threaten many species over waters and cooler deep waters,separating upper ma- time, especially mollusks and coral reefs. But not all rine life from nutrients found in deep water.The figure life forms will suffer: some types of phytoplankton shows changes in phytoplankton growth(vertically integrated annual mean primary production,or PP), and other photosynthetic organisms may benefit expressed as the percentage difference between 2090- from increases in CO2. Ocean acidification will 2099 and 1860-1869)per 1°C(1.8°F)of global warm- continue to worsen if CO2 emissions continue un- ing.Source: National Research Council,2011a abated in the decades ahead. 28 How will agriculture and food production be affected? The stress of climate change water resources from glacial melt and on farming may threaten snowpack. global food security.Although Modeling indicates that the an increase in the amount of CO2-related benefits for some CO2 in the atmosphere favors crops will largely be outweighed the growth of many plants, it ; by negative factors if global tem- does not necessarily translate intoperature rises more than 1.0°C • more food. Crops tend to grow i i (1.81)from late 20th-century values more quickly in higher temperatures, (Figure 28),with the following project- leading to shorter growing periods ed impacts: and less time to produce grains. In addition, a For each degree of warming, yields of corn in changing climate will bring other hazards, including greater water stress and the risk of higher the United States and Africa, and wheat in temperature peaks that can quickly damage crops. India, drop by 5-15% Agricultural impacts will vary across regions and by 0 Crop pests, weeds, and disease shift in crop. Moderate warming and associated increases geographic range and frequency in CO2 and changes in precipitation are expected 0 If ST(9°F)of global warming were to be to benefit crop and pasture lands in middle to high reached, most regions of the world would latitudes but decrease yield in seasonally dry and experience yield losses, and global grain prices low-latitude areas. In California,where half the would potentially double nation's fruit and vegetable crops are grown, climate Growers in prosperous areas may be able to adapt change is projected to decrease yields of almonds, to these threats,for example by varying the crops walnuts, avocados, and table grapes by up to 40 which they grow and the times at which they are percent by 2050. Regional assessments for other grown. However,adaptation may be less effective parts of the world consistently conclude that climate where local warming exceeds 2°C(3.6°F)and will be change presents serious risk to critical staple crops limited in the tropics,where the growing season is in sub-Saharan African and in places that rely on restricted by moisture rather than temperature. 40 Loss of Crop Yields per Degree 20 I Warming Yields of corn in the United States and Africa,and wheat in India, 0 are projected to drop by 5-15%per de- gree of global warming.This figure also t-20 shows projected changes in yield per degree of warming for U.S.soybeans -40 US Maize and Asian rice.The expected impacts on r � US Soybean I crop yield are from both warming and -60 : Asia Rice CO2 increases, assuming no crop adap- India Wheat tation. Shaded regions show the likely Africa Maize -80 J ranges(67%)of projections.Values of 0 1 2 3 4 global temperature change are relative to the preindustrial value;current global Global Temperature Change(C) temperatures are roughly 0.7°C(1.3°F) above that value.Source:National Re- search Council,2011 a 29 q i 1 7 Mr, strong body of As a result, decision makers of all types—including evidence shows that individuals, businesses, and governments at all levels— climate change is occurring, are taking or planning actions to respond to climate is caused largely by human change. Depending on how much emissions are activities, and poses signifi- curtailed, the future could bring a relatively mild cant risks for a broad range change in climate or it could deliver extreme of human and natural changes that could last thousands of years. The systems. nation's scientific enterprise can contribute both by continuing to improve understanding of the causes and consequences of climate change and by improving and expanding the options available to limit the magnitude of climate change and to adapt to its impacts. 30 How does science inform emissions choices? As discussed in Part II of this booklet, improve- Even with expected improvements in energy ef- ments in the ability to predict climate change ficiency, if the world continues with "business as impacts per degree of warming has made it easier usual" in the way it uses and produce energy, CO2 to evaluate the risks of climate change. Policymak- emissions will continue to accumulate in the atmo- ers are left to address two fundamental questions: sphere and warm Earth.2 As illustrated in Figure 29, (1) at what level of warming are risks acceptable to keep atmospheric concentrations of CO2 roughly given the cost of limiting them; and (2)what level steady for a few decades at any given level to avoid of emissions will keep Earth within that level of increasing climate change impacts, global emissions warming? Science cannot answer the first question, would have to be reduced by 80%. because it involves many value judgments outside Another helpful concept is that the amount of the realm of science. However, much progress has warming expected to occur from CO2 emissions been made in answering the second. depends on the cumulative amount of carbon emis- sions, not on how quickly or slowly the carbon is 30added to the atmosphere(Figure 30). Humans have r 25Increasing emissions emitted about 500 billion tons(gigatonnes)of car- 20 y Stable emissions bon to date. Best estimates indicate that adding cc 15 % about 1,150 billion tons of carbon to the air would ° N 10 % lead to a global mean warming of 2°C (3.61). . F g0%less E u3 5 remissions 20ther greenhouse gases are a factor,but CO2 is by far 1960 1980 2000 2020 2040 2060 2080 2100 the most important greenhouse gas in terms of long-term Year climate change effects. P-900 0 800 Increasing o concentrations 0 700 3,000 600 2,500 U R $500 ` o_ 2,000 Stable a400 concentration w 1,500 0300- < 1960 1980 2000 2020 2040 2060 2080 2100 2 1,000 - Year E U 500 - --- -- -- - __ __ _ Emitted to date Illustrative Example: How Emissions Relate to CO2 e 3 4 Concentrations. Sharp reductions in emissions are Global Mean Temperature Change(oC) needed to stop the rise in atmospheric concentrations of CO2 and meet any chosen stabilization target.The graphs show how changes in carbon emissions(top panel)are related to changes in atmospheric concen- Cumulative Emissions and Increases in Global Mean trations(bottom panel).It would take an 80%reduc- Temperature Recent studies show that for a particular tion in emissions(green line,top panel)to stabilize choice of climate stabilization temperature,there would atmospheric concentrations(green line,bottom panel) be only a certain range of allowable cumulative carbon for any chosen stabilization target.Stabilizing emis- emissions. Humans have emitted a total of about 500 bil- sions(blue line,top panel)would result in a continued lion tons(gigatonnes)of carbon emissions to date.The rise in atmospheric concentrations(blue line, bottom error bars account for estimated uncertainties in both panel),but not as steep as a rise if emissions continue the carbon cycle(how fast CO2 will be taken up by the to increase(red lines).Source: National Research Council, oceans)and in the climate responses to CO2 emissions. 2011 a Source: National Research Council,2011 a 31 Emissions Reduction Scenarios Adding CO2 more quickly would bring temperaZZ - tures to that value more quick) but the value itself ° quickly, y Total Emissions Budget would change very little. W °1 2041-2050 Because cumulative emissions are what matters, 9 I E2oa1-2oao policies oriented toward the very long term(several 02021-2030 decades into the future) might be able to focus less 2011-2020 on specifying exactly when reductions must take place and more on how much total emissions are al- No change Agressive Very Reductions Agressive lowed over a long period—in effect, a carbon budget. Reductions Such a budget would specify the amount of total greenhouse gas that can be emitted during a speci- Meeting an Emissions Budget Meeting any emissions fied period of time(say, between now and 2050). budget will be easier the sooner and more aggressively actions are taken to reduce emissions.Source: National Meeting any specific emissions budget is more Research Council likely the earlier and more aggressively work is done to reduce emissions(Figure 31). It's like going on a reach that goal if he or she begins eating less and diet. If a person wants to lose 40 pounds by a cer- exercising more as soon as possible, rather than tain event in the future, it would be much easier to waiting to start until the month before the event. What are the choices for reducing greenhouse gas emissions? As discussed earlier, to limit climate India will continue to grow. Thus, change in the long term,the most reductions in U.S. emissions important greenhouse gas to control alone will not be adequate to is carbon dioxide which in the avert climate change risks. United States is emitted primarily " , However, strong U.S. lead- as a result of burning fossil fuels. " ership—demonstrated Figure 32 shows the relative \ through strong domestic amount of emissions from resi- 1 actions, may help influ- dential, commercial, industrial, . ence other countries to and transportation sources. It's i pursue serious emission not really a matter of doing with- reduction efforts as well. out, but being smarter about how we Several key opportunities to produce and use energy. reduce how much carbon dioxide The United States is responsible for about accumulates in the atmosphere are half of the human-produced CO2 emissions already available(Figure 33), including: in the atmosphere and currently accounts for Reduce underlying demand for goods and ser- roughly 20%of global CO2 emissions, despite hav- vices that require energy,for example, expand ing only 5%of the world's population. The U.S. education and incentive programs to influence percentage of total global emissions is projected to consumer behavior and preferences; curtail sprawl- decline over the coming decades as emissions ing development patterns that further our depen- from rapidly developing nations such as China and dence on petroleum. 32 2,000 ■From Direct Fossil Fuel Combustion 1,750 w ■From Electricity Combustion 0 1,500 1,340 v ° 990 1'132 investments and on the behavioral and consumer 1,000 choices of individual households. Governments at v 0 500 federal, state, and local levels have a large role to play in influencing these key stakeholders through 0 0 0 11 �Z 75 7Zo effective policies and incentives. In general, there are four major tool chests from which to select policies E -° ° for driving emission reductions: o a v � • Pricing of emissions such as by means of a car- bon tax or cap-and-trade system; U.S.greenhouse gas emissions in 2009 show the rela- . mandates or regulations that could include tive contribution from four end-uses: residential,com- mercial(e.g., retail stores,office buildings), industrial, direct controls on emitters(for example, and transportation. Electricity consumption accounts through the Clean Air Act)or mandates such as for the majority of energy use in the residential and automobile fuel economy standards, appliance commercial sectors. Image courtesy: U.S. Environmental Protection Agency efficiency standards, labeling requirements, building codes, and renewable or low-carbon Improve the efficiency with which energy is portfolio standards for electricity generation; used, for example, use more efficient methods for public subsidies for emission-reducing choices insulating, heating, cooling, and lighting buildings; through the tax code, appropriations, or loan upgrade industrial equipment and processes to be guarantees; and more energy efficient; and encourage the purchase . providing information and education and pro- of efficient home appliances and vehicles. moting voluntary measures to reduce emissions. Expand the use of low- and zero-carbon energy A comprehensive national program would likely sources, for example, switch from coal and oil to use tools from all of these areas. Most economists natural gas, expand the use of nuclear power and and policy analysts have concluded, however,that renewable energy sources such as solar, wind, geo- putting a price on CO2 emissions that is sufficiently thermal, hydropower, and biomass; capture and high and rises over time is the least costly path to sequester CO2 from power plants and factories. significantly reduce emissions;and it is the most ef- Capture and sequester CO2 directly from the ficient incentive for innovation and the long-term atmosphere,for example, manage forests and soils investments necessary to develop and deploy energy to enhance carbon uptake; develop mechanical efficient and low-carbon technologies and infrastruc- methods to "scrub" CO2 directly from ambient air. ture. Complementary policies may also be needed, Advancing these opportunities to reduce emis- however,to ensure rapid progress in key areas. sions will depend to a large degree on private sector population, Key Opportunities for Reducing income energy efficiency Emissions A chain of factors deter- household size, demand for goods of goods production —1 demand for mine how much CO accumulates in consumer behavior and services and service deliver energy 2 Y the atmosphere.Better outcomes and preferences (gold ellipses)could result if the nation focuses on several opportunities within each of the blue boxes.Source: if National Research Council,2010b post-emission carbon atmospheric CO, CO, concentration E— carbon emissions 4 intensity of management energy provided 33 Opportunities to Reduce Other Human- food, and also nitrous oxide and methane from Produced Warming Agents manure and nitrogen fertilizer.These emissions can There are opportunities to reduce emissions of non- be reduced in many ways, including by employing CO2 gases,such as methane, nitrous oxide,and precision agriculture" techniques that help farmers minimize the over-fertilization practices that lead to some industrial gases(e.g., hydrofluorocarbons), emissions, and by improving livestock waste man- which comprise at least 15%of U.S.greenhouse gas agement systems. emissions. Molecule for molecule,these gases are generally much stronger climate forcing agents than Some short–lived pollutants that are not green- 0O21 although carbon dioxide is the most important house gases also cause warming. One example is contributor to climate change over the long-term black carbon, or soot, emitted from the burning because of its abundance and long lifetime. of fossil fuels, biofuels, and biomass(for example, Some non-0O2 greenhouse gases can be re- the dung used in cookstoves in many developing duced at negative or modest incremental costs. For countries). Black carbon can cause strong local or example, reducing methane leaks from oil and gas regional-scale atmospheric warming where it is systems, coal mining, and landfills is cost-effective emitted. It can also amplify warming in some re- because there is a market for the recovered gas. gions by leaving a heat-absorbing black coating on Reducing methane also improves air quality. otherwise reflective surfaces such as arctic ice and snow. Reducing emissions of these short-lived warm- The largest overall source of non-0O2 green- ing agents could help ease climate change in the house emissions is from agriculture, in particular, near term. methane produced when livestock digest their What are the choices for preparing for the impacts of climate change? AIthough adaptation planning and search that focuses on climate change response efforts are under way adaptation actions. In the short term, in a number of states, counties, and adaptation actions most easily de- communities, much of the nation's ployed include low-cost strategies experience is in protecting its peo- that offer near-term co-benefits, or ple, resources, and infrastructure -- actions that reverse maladaptive are based on the historic record of policies and practices. In the longer climate variability during a time of term, more dramatic, higher cost relatively stable climate.Adaptation to responses may be required.Table 1 climate change calls for a different para provides a few examples of short-term ac- digm—one that considers a range of possible tions that might be considered to address some future climate conditions and associated impacts, of the expected impacts of sea-level rise. some well outside the realm of past experience. Even though there are still uncertainties regarding Adaptation efforts are hampered by a lack of solid the exact nature and magnitude of climate change information about benefits, costs, and the potential impacts, mobilizing now to increase the nation's and limits of different responses.This is due in part adaptive capacity can be viewed as an insurance pol- to the diversity of impacts and vulnerabilities across icy against climate change risks.The federal govern- the United States and the relatively small body of re- ment could play a significant role as a catalyst and 34 0 a N C d +-' R 9 O Impact Possible adaptation action U. %n a z Gradual inundation of Site and design all future public works projects to take sea level rise into account ■ ■ ■ low-lying land; Eliminate public subsidies for development in high hazard areas along thecoast ■ ■ loss of coastal habitats, especially coastal wetlands; Develop strong,well-planned,shoreline retreat or relocation plans/programs saltwater intrustion into (public infrastructure and private properties),and post-storm redevelopment plans ■ ■ coastal aquifers and rivers; Retrofit/protect public infrastructure(stormwater/wastewater systems,energy increased shoreline erosion • • • facilities,roads,causeways,ports,bridges,etc.) and loss of barrier islands; changes in navigational Use natural shorelines,setbacks,and buffer zones to allow inland migration of ■ ■ ■ ■ conditions shore habitats and barrier islands overtime(e.g.,dunes and forested buffers) Encourage alternatives to shoreline"armoring"through"living shorelines" ■ ■ ■ ■ TABLE 1. Examples of some adaptation options for one expected outcome of sea-level rise. coordinator of local and regional efforts by providing climate change, the United States can be indirectly technical and scientific resources, incentives to begin affected by the impacts of climate change occurring adaptation planning, guidance across jurisdictions, elsewhere in the world.Thus, it is in the country's a platform to share lessons learned, and support of interest to help enhance the adaptive capacity of scientific research to expand knowledge of impacts other nations, particularly developing countries that and adaptation. In addition to the direct impacts of lack resources and expertise. Why take action if there are still uncertainties about the risks of climate change? Further research will never completely eliminate Some climate change impacts, once manifest- uncertainties about climate change and its risks, ed, will persist for hundreds or even thousands given the inherent complexities of the climate sys- of years and will be difficult or impossible to tem and the many behavioral, economic, and tech- "undo." In contrast, many actions taken to re- nological factors that are difficult to predict into the spond to climate change could be reversed or future. However, uncertainty is not a reason for inac- scaled back if they somehow prove to be more tion, and there are many things we already know stringent than actually needed. about climate change that we can act on. Reasons Each day around the world, major investments for taking action include the following: are being made in equipment and infrastruc- • The sooner that serious efforts to reduce green- ture that can "lock in" commitments to more house gas emissions proceed, the lower the risks greenhouse gas emissions for decades to posed by climate change and the less pressure come. Getting the relevant incentives and poli- there will be to make larger, more rapid, and cies in place now will provide crucial guidance potentially more expensive reductions later. for these investment decisions. 35 oil • Many actions that could be taken to reduce y�6lM ��■■• vulnerability to climate change impacts are �;•a+,E i■■■• common sense investments that also will offer � � +■■■" protection against natural climate variations and extreme events. The challenge for society is to weigh the risks and benefits and make wise choices even knowing there are uncertainties, as is done in so many other realms, for example,when people buy home insurance.A valuable framework for supporting climate choices is an iterative risk management approach.This refers to a process of systematically identifying risks range of possible futures; and adjusting responses and possible response options; advancing a portfolio over time to take advantage of new knowledge, in- of actions that are likely to reduce risks across a formation, and technological capabilities. Conclusion Responding to climate change is about making and other decision makers across the nation; and choices in the face of risk. Any course of action those choices will involve numerous value judg- carries potential risks and costs; but doing nothing ments beyond the reach of science. However, may pose the greatest risk from climate change and robust scientific knowledge and analyses are a its impacts. America's climate choices will be made crucial foundation for informing choices. by elected officials, business leaders, individuals, rtsrsrar � t; ' fa' -- 36 REFERENCES National Research Council, 2010a, Advancing the Science of Climate Change National Research Council, 2010b, Limiting the Magnitude of Climate Change National Research Council, 2010c, Adapting to the Impacts of Climate Change National Research Council, 2011 d, Informing an Effective Response to Climate Change National Research Council, 2010e, Ocean Acidification:A National Strategy to Meet the Challenges of a Changing Ocean National Research Council 2011 a, Climate Stabilization Targets: Emissions, Concentrations, and Impacts for Decades to Millennia National Research Council, 2011 c, America's Climate Choices For more information, contact the Board on Atmospheric Sciences and Climate at 202-334-3512 or visit http://dels.nas.edu/basc. A video based on Part I of this booklet is available at http://americasclimatechoices.org. This booklet was prepared by the National Research Council with support from the National Oceanic and Atmospheric Administration(NOAH). It was developed by Nancy Huddleston and designed by Francesca Moghari. Special thanks to Ian Kraucunas,Antonio J. Busalacchi, Jr., Edward J. Dunlea, Robert W. Fri, Laurie Geller, Pamela A. Matson, Damon Matthews, Gerald A. Meehl, Claudia Mengelt, Raymond T. Pierrehumbert, Kimberly A. Prather,John P. Reisman, and Benjamin D. Santer for their helpful contributions. Photo Credits Main cover photo by Michael D.Dudzik; cover thumbnail(bottom)by Fuse; p. 1 by John P. Kelley(Image Bank); p. 17 by Joe McDonald; p. 19 courtesy United States Geological Survey; p.20 by Randy Well(Stone); p. 23, p. 27 by David Haines; p. 30,Jupiter Images(Comstock); p. 36, kali9. Photo on p. 2 by Mike Waszkiewicz, courtesy National Science Foundation. Nicole Spaulding and Kristin Schild,students from the University of Maine Climate Change Institute,chip out near-surface ice samples as part of research into new methods for sampling the record of polar climate change. ©2012 National Academy of Sciences About the National Research Council The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government.The Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering and is administered jointly by both Academies and the Institute of Medicine. The National Research Council enlists the nation's foremost scientists, engineers, health professionals, and other experts to serve on committees to address scientific and technical aspects of some of the nation's most pressing problems.These experts serve pro bono and are screened for conflicts of interest to ensure that the committee is able to provide impartial and objective advice.Through these committees, the Academies produce about 200 peer-reviewed reports each year that provide thoughtful analysis and helpful direction to policymakers and stakeholders. How do we know that Earth has warmed? How do we know that humans are causing greenhouse gas concentrations to increase? How do we know the current warming trend isn't caused by the Sun? How do we know that the warming trend is not caused by natural cycles? How much more warming can be expected? How is precipitation expected to change? How will sea ice and snow be affected? How will coastlines be affected? How will ecosystems be affected? How will agriculture and food production be affected? Hover: does science inform the response to climate change? THE NATIONAL ACADEMIES Advisers to the Notion on Science,Engineering, and Medicine The nation turns to the National Academies—National Academy of Sciences,National Academy of Engineering, Institute of Medicine,and National Research Council— for independent,objective advice on issues that affect people's lives worldwide. www.national-academies.org