Global Climate SimulationsWindows on the World of Tomorrow

Renewable Energy Summit, Milwaukee, Wisconsin, March 13, 2008

Mark A. ChandlerNASA Goddard Institute for Space Studiesat Columbia University

Fig. TS.2, IPCC 2007

Changes In Greenhouse Gases from Ice Core and Modern Data

CO2

CH4

N2O

Temperature retrievals from satellites now generally consistent with surface-based observations (except for the tropics)

Global Temperature Trends 1850-2005

Trend Length Years2550100150

Surface and TroposphereTrend Maps (1979-2005)

0.75-0.75°C per decade

What are Global Climate Models

and what do they project about the future?

Wind and Solar Climatologies

Computer Simulations of the Earth System

The GCM Grid

Increased Grid ResolutionRequires Increased Computing Power

Rule of thumb:10X more CPUfor a doubling ofresolution

Increased Resolution RequiresIncreased Computing Power

Circa 2000’s

Circa 1980’s

At every grid cell GCMs calculate:

Temperature (T)Pressure (P)Winds (U, V)Humidity (Q)

Fundamental Physical Quantities

T, P, U, V, and Q calculated and related to each other via:

GCM Fundamental Physical Equations

Seasonal and Diurnal CyclesLatent and Sensible Heat FluxesClouds and ConvectionPlanetary Boundary LayerGreenhouse GasesAerosolsSea IceGround HydrologyOcean Heat TransportOcean CirculationDynamic VegetationDynamic Ice SheetsCarbon Cycle Chemistry

Physical Processes Simulated by GCMs

Global_Warming_Sim2.R Model II 8/24/2000

Owner: Dr. Mark Chandler, chandler@giss.nasa.govGroup: Paleoclimate GroupThis experiment simulates climate change based on a1 percent/year increase in CO2

Object modules:MainC9 DiagC9 RadC9FFTC9UTILC9

Data input files:7=G8X10_600Ma9=NOV1910.rsf_snowball15=O8X10_600Ma19=CD8X10_600Ma23=V8X10_600Ma26=Z8X101_600Ma21=RTAU.G25L1522=RPLK2529=Snowball_Earth_Regions

Label and Namelist:Global_Warming_Sim2 (Transient increase in CO2)

&INPUTZ TAUI=10176.,IYEAR=1900, KOCEAN=1, SRCOR=.95485638151, S0X=1.,CO2=.31746031746031, USET=0.,TAUE=35040., USESLP=-12., ISTART=3,KCOPY=2,NDPRNT=-1,TAUE=10177.,TAUP=95616.,

C** INITIALIZE SOME ARRAYS AT THE BEGINNING OF SPECIFIED DAYS fName = './prt/'//JMNTH0(1:3)//CYEAR//'.prt'//LABEL1(

IF(JDAY.NE.32) GO TO 294 JEQ=1+JM/2 DO 292 J=JEQ,JM DO 292 I=1,IM 292 TSFREZ(I,J,1)=JDAY JEQM1=JEQ-1 DO 293 J=1,JEQM1 DO 293 I=1,IM 293 TSFREZ(I,J,2)=JDAY GO TO 296 294 IF(JDAY.NE.213) GO TO 296 JEQM1=JM/2 DO 295 J=1,JEQM1 DO 295 I=1,IM 295 TSFREZ(I,J,1)=JDAY C**** INITIALIZE SOME ARRAYS AT THE BEGINNING OF EACH DAY 296 DO 297 J=1,JM DO 297 I=1,IM TDIURN(I,J,1)=1000. TDIURN(I,J,2)=-1000.

TDIURN(I,J,6)=-1000.

PEARTH=FDATA(I,J,2)*(1.-FDATA(I,J,3)) IF(PEARTH.GT.0.) GO TO 297 TSFREZ(I,J,1)=365. TSFREZ(I,J,2)=365. 297 CONTINUE

So, What Is a GCM Really?A Computer Program

Unix Scripts Fortran Code

GCMs Require High-Level Programming Skills

and Supercomputing Resources

Distributed Computing Climate Experiments

DOE

GISSModel E

NASA

GISSModel E

NSF

GISSModel E

National Lab Supercomputing Resources

PersonalComputers

EdGCMModel E

SchoolLabs

EdGCMModel E

UniversityClusters

EdGCMModel E

GSFC GISS LangleyScientific

Community

SimulationDistribution

Simulation Results Collection

Primary Server

Perturbed Physics Ensembles

Desktop Client Computing Resources

NASA MAP Climate Scientists

“Big Iron” Computing

Scarsdale Teachers Institute Workshop, March 3 and 4, 2006

Climate Computing @ Home and School

What are the model inputs and where do they come from?

•Population Prospects•Economic Development•Energy Demand•Resource Availability•Technological Change•Future Energy Systems•Land Use•Environmental Policy

Google: IPCC SRES

IPCC Special Report on Emissions Scenarios (SRES)

Figure SRES 5-1

An Example of the Greenhouse Gas Emissions Scenarios

Carbon Dioxide Scenarios

Figure SPM-5

Figure SPM-6

IPCC 2007Atm-Ocn GCM Projections of Surface Air Temperatures

0.0 8.0°C

IPCC 2007Atm-Ocn GCM Projections of Surface Air Temperatures

Fig. TS.29

Continental Temperature Anomalies: Observations and Projections

IPCC, WG1, 2007

Model Ensemble Changes in Temperature, Precip, Storminess

Carbon Dioxide Change Over Geologic Time

Mid-Pliocene

The Last Global Warming vs. The Coming Global Warming

Pliocene Sea Surface Temperature Anomaly(January)

∆T = +2.09°C

Simulated Change in Surface Air Temperature(Annual Average)

∆T = +2.1°C

3 Mya

2005

Pliocene Temperature Change: 3 MYA

+2.13 °C

+2.33 °C

2050s

The Last Global Warming vs. The Coming Global Warming

The North AtlanticConundrum

Pliocene DATA

IPCC AOGCM

Impacts at ∆ Global Mean Temperature

(R. Warren, in “Avoiding Dangerous Climate Change” 2006)

• 1°C: world ocean and arctic ecosystems damaged• 1.5°C: Greenland ice sheet melting starts; ecosystems damaged in

many regions• 2°C: Agricultural yields fall, 1-3 billion experience water

stress, sea level rise displaces millions, malaria risks spread, Arctic ecosystems collapse, extinctions soar, 97% of coral reefs gone, global ecosystems lose 5-66% of their extent;

• 2-3°C: Amazon and other forests and grasslands collapse, adding to CO2 increase

• 3°C: Millions at risk to water stress, flood, hunger, dengue and malaria increase, few ecosystems can adapt, losing 7-74% of extent

• 4°C: whole regions forced out of agriculture (Australia), thermohaline circulation could collapse, West Antarctic Ice Sheet melting may begin, increases in extreme weather, 60% loss of tundra

http://data.giss.nasa.gov/cgi-bin/cdrar/do_LTmapE.py

21st Century Global Warming

Climate Simulations for IPCC 2007 Report

► Climate Model Sensitivity 2.0-5.0ºC for 2xCO2 (consistent with paleoclimate data & other models)

► Simulations Consistent with 1880-2003 Observations

Source: Hansen et al., to be submitted to J. Geophys. Res.

IPCC MAIN FINDINGS

Working Group I – The climate is warming and humans are causing it. (90% Certainty)

Working Group II – Impacts are occurring now as a consequence of human-caused climate change. Specific future impacts have been identified. A portfolio of adaptation and mitigation measures can diminish the risks associated with climate change.

Working Group III – There is substantial potential for mitigation. Projected costs are ~3% of global GDP in 2030. All sectors, as well as changes in lifestyle and behavior patterns, can contribute to climate change mitigation.

Pliocene Global Warming: Main Findings

Global warming was 2-3°C higher than modern, similar to projected temperatures in the latter half of the 21st century.

Sea level was approximately 25 meters higher than today, indicating probably complete loss (collapse?) of Greenland and West Antarctic ice sheets.

North Atlantic ocean was a key area of warming in past global warming scenarios in contrast to the IPCCC AOGCM estimates of future climate change. If model’s are underestimating the climate change impact in the N. Atlantic global warming could proceed more rapidly than our current projections.