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Global CO2 Emissions (PgC/yr)MethodologyRisks of Global Mean Temperature Increase Since PreindustrialRisks of Ocean ImpactsWhy is the Reference distribution shifted To higher temperatures?MIT OpenCourseWare http://ocw.mit.edu15.023J / 12.848J / ESD.128J Global Climate Change: Economics, Science, and PolicySpring 2008For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms.15.023 - 12.848 - 12.308 - ESD.128 GLOBAL CLIMATE CHANGE : ECONOMICS, SCIENCE, AND POLICY THE CLIMATE MACHINE V: INTEGRATED ASSESSMENT I Sensitivity Studies and Uncertainty Analysis using the Integrated Global System Model R. PRINN, April 14, 2008 1. Structural & Parametric Uncertainty 2. Sensitivity Analysis 3. Uncertainty Analysis: IGSM 1 4. Uncertainty Analysis: IGSM 2.2 5. Communicating UncertaintyTWO TYPES OF UNCERTAINTY STRUCTURAL UNCERTAINTY PARAMETRIC UNCERTAINTY TWO TYPES OF ANALYSIS SENSITIVITY UNCERTAINTYAnthropogenic emissionsprediction and policyanalysis model 12 regions Terrestrial ecosystems model 0.5' x 0.5' Natural emissions model 1' x 1' 2.5' x 2.5' 2D land-ocean (7.8' x 9 levels) Coupled Atmospheric chemistry and climate model Agriculturalproduction Land vegetation change Land CO2 uptake Sea level Soil C Soil N Temperature Rainfall Ocean CO2 uptake CH4 N2O CO2, CH4, N2O, NOx, SOx, CO, CFCs, Temperature, Rainfall, clouds, CO2 Nutrients, pollutants Figure by MIT OpenCourseWare. Ref: Prinn et al, Climatic Change, 41, 469-546, 1999 Sensitivity Analysis using theMIT INTEGRATED GLOBAL SYSTEM MODEL VERSION 1Image removed due to copyright restrictions. See Table IV in: Prinn, R., et al. "Integrated Global System Model for Climate Policy Assessment: Feedbacks and Sensitivity Studies." Climatic Change 41, no. 3/4 (1999): 469-546. SENSITIVITY ANALYSIS: Defining the uncertain parametersCooler Runs Warmer Runs NEM model LLL LLL HLL HHH HHH Higher Lower Slower Higher H Higher Lower Lower Faster Higher L Lower LLH LLH Higher LLH LHH Higher Lower Slower Higher R R R R HHL HHL HHL Lower Lower Lower Faster Higher TEM model Coupled Chemistry/ Climate/ Ocean carbon model EPPA model Emissions Sensitivity Warming rate Ocean uptake Aerosol O.D. [p, e, b] [K, a] [S] Figure by MIT OpenCourseWare. Ref: Prinn et al, Climatic Change, 41, 469-546, 1999 Schematic illustrating the seven runs performed for the Sensitivity Analysis of the IGSM 1. Open ellipses denote points in sequence where output is available, with the letters in the ellipse denoting the identifying symbol for the output.Ref: Prinn et al, Climatic Change, 41, 469-546, 1999 Figure by MIT OpenCourseWare. Degrees centigrade 10.0 8.0 6.0 4.0 2.0 0.0 90 60 30 0 -30 -60 -90 Latitude SouthNorth HHH LHH HHL RRR HLL LLHLLL Sensitivity of Temperature Change from 1990 to 2100 to assumed: Emissions (p, e, b); Ocean Heat & Carbon Uptake and Aerosol Forcing (K, a); & Climate Sensitivity (s)Figure by MIT OpenCourseWare.THE MAJOR CLIMATE FORECAST MODEL UNCERTAINTIES INVOLVE CLOUDS, OCEAN MIXING& AEROSOL FORCING.ADDED TO THESEARE SUBSTANTIALUNCERTAINTIESIN EMISSIONFORECASTINGTHESE UNCERTAINTIES ARE CONSTRAINED BY OBSERVATIONSTO ESTIMATE THE PDFsOF VARIOUS MEASURES OF CLIMATE CHANGE,WE USE VERY LARGE ENSEMBLES OF IGSM RUNS ,EACH WITH RANDOMLY CHOSEN EQUAL PROBABILITY CHOICES FOR THE UNCERTAIN MODEL PARAMETERS. Uncertainty Analysis using theMIT INTEGRATED GLOBAL SYSTEM MODEL VERSION 1• 250 runs of the MIT IGSM with Latin hypercube sampling of uncertain model parameters • No explicit policy and stringent policy (at or below 550ppm CO2 equivalent) cases • Policy should lower probability of damaging outcomes Uncertainty Analysis MethodTO ADDRESS UNCERTAINTY MIT CLIMATE MODEL HAS FLEXIBLE SENSITIVITY, OCEAN MIXING & AEROSOL FORCING WHOSE UNCERTAINTIES ARE CONSTRAINED BY OBSERVATIONS Images removed due to copyright restrictions. See Figure 4 in: Forest, Chris, et al. "Quantifying Uncertainties in Climate System Properties with the Use of Recent Climate Observations." Science 295 (2002): 113-117.PROBABILITY RANGES FOR NO-POLICY CASE OF EMISSIONS OF SELECTED CLIMATE-FORCING & POLLUTING GASES (EPPA cf. SRES) Global CO2 Emissions (PgC/yr) 50 40 30 20 10 0 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 Year Mean +/-Standard Deviation95%Probability BoundsIPCC SRES Scenarios 1200 1000 800 600 400 200 0 1990 2000 2010 2020 2030 Global NOxGlobal NOxMean +/-Standard Deviation95% Probability BoundsIPCC SRES Scenarios xx2040 2050 2060 2070 2080 2090 2100 Year Emissions (Tg/yr)Emissions (Tg/yr)CO2 Emissions (Gt C) 2100 Global SO2Global SOEmissions (Tg/yr)2Emissions (Tg/yr)Ref: Webster et al, Atmos. Environ.,2002 Courtesy Elsevier, Inc., http://www.sciencedirect.com. Used with permission.Projected changes in atmospheric CO2 concentrations relative to 1990. Solid lines show the lower 95%, median, and upper 95% in the absence of greenhouse gas restrictions, and dashed lines show the lower 95%, median, and upper 95% under a policy that approximately stabilizes CO2 concentrations at 550 ppm. Source: Webster et al., Climatic Change, 2003 (MIT JPSPGC Report No. 95)Projected changes in radiative forcing relative to 1990 due to all greenhouse gases. Solid lines show the lower 95%, median, and upper 95% in the absence of greenhouse gas restrictions, and dashed lines show the lower 95%, median, and upper 95% under a policy that approximately stabilizes CO2 concentrations at 550 ppm. Source: Webster et al., Climatic Change, 2003 (MIT JPSPGC Report No. 95)Projected changes in global mean surface temperature relative to 1990. Solid lines show the lower 95%, median, and upper 95% in the absence of greenhouse gas restrictions, and dashed lines show the lower 95%, median, and upper 95% under a policy that approximately stabilizes CO2 concentrations at 550 ppm. Source: Webster et al., Climatic Change, 2003 (MIT JPSPGC Report No. 95)POLICY LOWERS PROBABILITY OF DANGEROUS AMOUNTS OF WARMING POLICY LOWERS PROBABILITY OF DANGEROUS AMOUNT OF SEA LEVEL RISE Source: Webster et al., Climatic Change, 2003 (MIT JPSPGC Report No. 95) FULL PDF’S OF KEY MEASURES OF CLIMATE CHANGE for 1990-2100, WITH & WITHOUT the (550 ppm) POLICYHUMAN AND NATURAL COMPONENTS CONTRIBUTE SIMILARLY TO TOTAL UNCERTAINTY Probability distributions of global mean surface temperature change from 1990 to 2100 from all uncertain parameters (solid blue), only climate model parameters uncertain and emissions fixed (dotted red), and only


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