Intergovernmental Panel on Intergovernmental Panel on Climate Change (IPCC)Climate Change (IPCC)

• Established by the UN and World Meteorological Established by the UN and World Meteorological Organization in 1988Organization in 1988

• Role of the IPCC: to assess the scientific, Role of the IPCC: to assess the scientific, technical, and socio-economic information technical, and socio-economic information relevant for the understanding of the risks of relevant for the understanding of the risks of human-induced climate change.human-induced climate change.

• Assessments based on published and peer-Assessments based on published and peer-reviewed literaturereviewed literature

Intergovernmental Panel on Intergovernmental Panel on Climate Change (IPCC)Climate Change (IPCC)

• 2,500 of the world’s leading climate scientists and 2,500 of the world’s leading climate scientists and technical experts contribute to reportstechnical experts contribute to reports

• Provides comprehensive and balanced assessments Provides comprehensive and balanced assessments of climate change science, impacts, and adaptation of climate change science, impacts, and adaptation and mitigation optionsand mitigation options

• Extensive peer-review and governmental review Extensive peer-review and governmental review ensures scientific credibility and policy relevanceensures scientific credibility and policy relevance

Intergovernmental Panel on Climate Change (IPCC)Intergovernmental Panel on Climate Change (IPCC)

Working Group IWorking Group IClimate changeClimate change

sciencescience

Working Group IIWorking Group IIImpacts, Impacts,

adaptation andadaptation andvulnerabilityvulnerability

Working Group IIIWorking Group IIIMitigationMitigation

Task forceTask forceon nationalon national

greenhouse gasgreenhouse gasinventoriesinventories

Technical supportTechnical supportunit (TSU) inunit (TSU) in

United KingdomUnited Kingdom

TSU inTSU inUnited StatesUnited States

TSU inTSU inThe NetherlandsThe Netherlands

TSU inTSU inJapanJapan

PlenaryPlenaryIPCC SecretariatIPCC Secretariat

WMO/UNEPWMO/UNEPSwitzerlandSwitzerland

Experts, authors, contributors, reviewersExperts, authors, contributors, reviewers

Source: Redrawn from Vital Climate Graphics

IPCC Assessment ReportsIPCC Assessment Reports

• Standard reference workStandard reference work• First Assessment Report (FAR) - published in 1990First Assessment Report (FAR) - published in 1990

– Projected increase in temperature of 3 - 8 °FProjected increase in temperature of 3 - 8 °F

– Consequences: rising sea levels, increase in extreme Consequences: rising sea levels, increase in extreme weather events, serious pressure on aquatic and terrestrial weather events, serious pressure on aquatic and terrestrial ecosystemsecosystems

– ““The size of the warming is broadly consistent with The size of the warming is broadly consistent with predictions of climate models, . . . but the unequivocal predictions of climate models, . . . but the unequivocal detection of the enhanced greenhouse effect from detection of the enhanced greenhouse effect from observations is not likely for a decade or moreobservations is not likely for a decade or more.”.”

IPCC Assessment report foci

19901995

2001

• Climate has changed over the past centuryClimate has changed over the past century– Global mean surface air temperature has increased .5-1Global mean surface air temperature has increased .5-1oo FF– Global sea level has risen 4-10 inchesGlobal sea level has risen 4-10 inches– Global precipitation over land has increased 1%Global precipitation over land has increased 1%

• “ “ Human signal still building . . . Nevertheless, the balance Human signal still building . . . Nevertheless, the balance of evidence suggests a discernible human influence on global of evidence suggests a discernible human influence on global climate.”climate.”

IPCC Second Assessment IPCC Second Assessment Report ConclusionsReport Conclusions

• Climate has changed over the past centuryClimate has changed over the past century– Global mean surface air temperature has increased .5-1Global mean surface air temperature has increased .5-1oo FF– Global sea level has risen 4-10 inchesGlobal sea level has risen 4-10 inches– Global precipitation over land has increased 1%Global precipitation over land has increased 1%

• “ “ Human signal still building . . . Nevertheless, the balance of Human signal still building . . . Nevertheless, the balance of evidence suggests a discernible human influence on global evidence suggests a discernible human influence on global climate.”climate.”

• Climate is expected to continue to change in the futureClimate is expected to continue to change in the future– Projected temperature increase of 1.8-6.3Projected temperature increase of 1.8-6.3ooF by 2100F by 2100– Projected sea-level rise of 6-37 inches by 2100Projected sea-level rise of 6-37 inches by 2100– Likely increase in extreme weather eventsLikely increase in extreme weather events

IPCC Second Assessment IPCC Second Assessment Report ConclusionsReport Conclusions

Kyoto ProtocolKyoto Protocol

• SAR provided key input to the negotiations SAR provided key input to the negotiations that led to the adoption of the Kyoto that led to the adoption of the Kyoto Protocol in 1997Protocol in 1997

• Is an international agreement that Is an international agreement that establishes binding targets for reduction of establishes binding targets for reduction of greenhouse gases emitted by developed greenhouse gases emitted by developed countries.countries.

Emission ScenariosEmission Scenarios• SAR - used scenarios developed in 1992, known as the SAR - used scenarios developed in 1992, known as the

IS92 seriesIS92 series • Alternative projections of population, affluence, and Alternative projections of population, affluence, and

technological change were used to come up with a technological change were used to come up with a range of future GHG emission scenariosrange of future GHG emission scenarios

• 1995 - IPCC evaluated the IS92 scenarios, 1995 - IPCC evaluated the IS92 scenarios, recommended that a new set of scenarios be developed recommended that a new set of scenarios be developed - Special Report on Emission Scenarios- Special Report on Emission Scenarios

• TAR - projections are underlain by the full range of TAR - projections are underlain by the full range of SRES scenariosSRES scenarios

Third Assessment Report Third Assessment Report of the IPCCof the IPCC

• Published in 2001Published in 2001

• Emphasizes information from the last 5 Emphasizes information from the last 5 yearsyears

• Places climate change in the context of Places climate change in the context of sustainable development, emphasizing sustainable development, emphasizing equity issuesequity issues

• Policy relevant, but not policy prescriptivePolicy relevant, but not policy prescriptive

IPCC Third Assessment ReportIPCC Third Assessment ReportKey Findings of Working Group IKey Findings of Working Group I

““An increasing body of observations gives a An increasing body of observations gives a collective picture of a warming world and collective picture of a warming world and other changes in the climate system.”other changes in the climate system.”

Source: IPCC TAR 2001

Variations of the Variations of the Earth’s Surface Earth’s Surface Temperature*Temperature*

*relative to 1961-1990 average*relative to 1961-1990 average

Global Annual Temperature Trends:Global Annual Temperature Trends:1901 - 19901901 - 1990

Source: Watson 2000

U.S. Temperature Trends: 1901 to 1998U.S. Temperature Trends: 1901 to 1998

Red circles = warming; Blue circles = coolingRed circles = warming; Blue circles = coolingAll stations/trends displayed regardless of statistical significance.All stations/trends displayed regardless of statistical significance.

Source: National Climatic Data Center/NESDIS/NOAA

U.S. Precipitation Trends: 1901 to 1998U.S. Precipitation Trends: 1901 to 1998

Source: National Climatic Data Center/NESDIS/NOAA

GreenGreen •• = increasing, Brown= increasing, Brown •• = decreasing= decreasingAll stations/trends displayed regardless of statistical significanceAll stations/trends displayed regardless of statistical significance

Extreme Precipitation Events in the U.S.Extreme Precipitation Events in the U.S.

Source: Karl, et.al. 1996.

Increase in catastrophic flood eventsIncrease in catastrophic flood events

Increase in frequency and Increase in frequency and intensity of droughtsintensity of droughts

Source: OSTP

Snow cover and ice extent have decreasedSnow cover and ice extent have decreased

Global average sea level has risen Global average sea level has risen and ocean heat content has increasedand ocean heat content has increased

IPCC Third Assessment ReportIPCC Third Assessment ReportKey Findings of Working Group IKey Findings of Working Group I

““Emissions of greenhouse gases and aerosols Emissions of greenhouse gases and aerosols due to human activities continue to alter the due to human activities continue to alter the atmosphere in ways that are expected to atmosphere in ways that are expected to affect the climate.”affect the climate.”

Indicators of the Human InfluenceIndicators of the Human Influenceon the Atmosphere during the Industrial Eraon the Atmosphere during the Industrial Era

Source: IPCC TAR 2001

IPCC Third Assessment ReportIPCC Third Assessment ReportKey Findings of Working Group IKey Findings of Working Group I

““Confidence in the ability of models to Confidence in the ability of models to project future climate has increased.”project future climate has increased.”

IPCC Third Assessment ReportIPCC Third Assessment ReportKey Findings of Working Group IKey Findings of Working Group I

““There is new and stronger evidence that most There is new and stronger evidence that most of the warming observed over the last 50 of the warming observed over the last 50 years is attributable to human activities.”years is attributable to human activities.”

IPCC Third Assessment ReportIPCC Third Assessment ReportKey Findings of Working Group IKey Findings of Working Group I

““Human influences will continue to change Human influences will continue to change atmospheric composition throughout the atmospheric composition throughout the 21st century.”21st century.”

IPCC Third Assessment ReportIPCC Third Assessment ReportKey Findings of Working Group IKey Findings of Working Group I

““Global average temperature and sea level Global average temperature and sea level are projected to rise under all IPCC are projected to rise under all IPCC scenarios.”scenarios.”

Main Findings of WG I Main Findings of WG I • Extensive and wide-spread evidence that the earth is warming; Extensive and wide-spread evidence that the earth is warming;

we are already seeing the first clear signals of a changing we are already seeing the first clear signals of a changing climate.climate.

• Human activities are changing the atmospheric concentrations Human activities are changing the atmospheric concentrations of greenhouse gases.of greenhouse gases.

• New and stronger evidence of a human influence on climate.New and stronger evidence of a human influence on climate.

• Global temperature will rise from 2.5 to 10.4°F over this Global temperature will rise from 2.5 to 10.4°F over this century. century. Precipitation patterns will change, sea level will rise Precipitation patterns will change, sea level will rise

and extreme weather events will increase.and extreme weather events will increase. • Human influence will continue to grow during the next century Human influence will continue to grow during the next century

unless measures are taken to reduce GHG emissions.unless measures are taken to reduce GHG emissions.

IPCC History: Evolution of IPCC History: Evolution of Our KnowledgeOur Knowledge

• FAR (1990): “FAR (1990): “The size of the warming is broadly The size of the warming is broadly consistent with predictions of climate models, . . . but the consistent with predictions of climate models, . . . but the unequivocal detection of the enhanced greenhouse effect unequivocal detection of the enhanced greenhouse effect from observations is not likely for a decade or more.”from observations is not likely for a decade or more.”

• SAR (1996):SAR (1996): “The balance of evidence suggests a “The balance of evidence suggests a discernible human influence on climate.”discernible human influence on climate.”

• TAR (2001):TAR (2001): “There is new and stronger evidence that “There is new and stronger evidence that most of the warming observed over the last 50 years is most of the warming observed over the last 50 years is attributable to human activities.”attributable to human activities.”

IPCC Scenario formulation

Data vs. Models in Science

Data tell us about the past– But in nonlinear systems (like climate), past trends not

necessarily predictive of future

Models project the future– Connect theory with data– Can work with nonlinear systems

But how do we know models are correct?– Right answers for wrong reasons

Climate Models

3-dimensional mathematical simulations – based on “first principles”: physical equations of motion and

state

– transport of heat, moisture, energy– grids (4-5° latitude, or 400-500 km)– time steps (15-30 minutes)– long-term simulations (years to centuries)

Computationally expensive– hundreds of supercomputer hours per run

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General Circulation Models

Governed by physics:

- Law of Continuity- Equation of State- Conservation of energy- Conservation of momentum

Input: solar forcing, Earth rotation, seasons, initial conditions, greenhouse gas levels

Output: temperature, precip, pressures, winds, ocean currents, heat transport, deep ocean circulation…

Run a GCM on your computer?http://www.edgcm.org/

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are needed to see this picture.

One “experiment” takes 3-4 days of cpu time

SRES Scenarios

The A1 storyline and scenario family describes a future world of very rapid economic growth, low population growth, and the rapid introduction of new and more efficient technologies. Major underlying themes are convergence among regions, capacity building, and increased cultural and social interactions, with a substantial reduction in regional differences in per capita income.

The A2 storyline and scenario family describes a very heterogeneous world. The underlying theme is self-reliance and preservation of local identities. Fertility patterns across regions converge very slowly, which results in high population growth. Economic development is primarily regionally oriented.

The B1 storyline and scenario family describes a convergent world with the same low population growth as in the A1 storyline, but with rapid changes in economic structures toward a service and information economy, with reductions in material intensity, and the introduction of clean and resource-efficient technologies. Global solutions to economic, social, and environmental sustainability, including improved equity, but without additional climate initiatives.

The B2 storyline and scenario family describes a world in which the emphasis is on local solutions to economic, social, and environmental sustainability. It is a world with moderate population growth, intermediate levels of economic development, and less rapid and more diverse technological change than in the B1 and A1 storylines. While the scenario is also oriented toward environmental protection and social equity, it focuses on local and regional levels.

COCO22 and SO and SO22 in the 21 in the 21stst Century Century

Source: IPCC TAR 2001

Global average temperature Global average temperature is projected to increase by is projected to increase by 1.4 - 5.8°C by 21001.4 - 5.8°C by 2100

Projected temperature Projected temperature increases are increases are greatergreater than than those in the SARthose in the SAR

Projected rate of warming is Projected rate of warming is unprecedented for last unprecedented for last 10,000 years10,000 years

Temperature ProjectionsTemperature Projections

Source: IPCC TAR 2001

1000AD to 1861, N. 1000AD to 1861, N. Hemisphere, proxy Hemisphere, proxy data data

1861 to 2000, Global, 1861 to 2000, Global, instrumentalinstrumental

2000 to 2100, SRES 2000 to 2100, SRES projectionsprojections

Source: IPCC TAR 2001

Variations of the Earth’s SurfaceVariations of the Earth’s SurfaceTemperature - 1000 to 2100Temperature - 1000 to 2100

Projected Changes in Annual Temperatures for the 2050sProjected Changes in Annual Temperatures for the 2050s

The projected change is compared to the present day with a ~1% increase per year in equivalent COThe projected change is compared to the present day with a ~1% increase per year in equivalent CO 22

Source: The Met Office. Hadley Center for Climate Prediction and Research

A probabilistic view…

“With the climatological probability of a hot summer represented by two faces (say painted red) of a six-faced die, judging from our model by the 1990s three or four of the six die faces will be red. It seems to us that this is a sufficient ‘loading’ of the dice that it will be noticeable to the man in the street.”

Hansen et al., J. Geophys. Res. 93, 9341-9364, 1988.

Metro NYC region: Impact study

Ulster

Suffolk

Sullivan

Orange

Litchfield

Ocean

Dutchess

Fairfield

Morris

Sussex

New Haven

Warren

Monmouth

Hunterdon

Westchester

Nassau

Bergen

Putnam

Mercer

Somerset

Middlesex

Passaic

Essex

Rockland

Union

QueensKings

Bronx

Hudson

Richmond

New York

31 counties in 3 states (NY, NJ, CT)21 million residents13,000 square milesVariety of pop densities & land uses

Estimated Increases in Ozone Excedences ( 1 hour >120 ppb)for the New York Metro Region by 2050

1990 Hottest Summer Climate

2050 A2 Hottest

Summer Climate

1990 air pollutant emissions

786 3,266

2050 A2 air pollutant emissions

1,745 7,489

(from C. Hogrefe et al, 2003)

(+122%)

(+315%)

(+749%)

Temperature & Mortality Relationship in 11 Eastern US Cities

(Curreiro et al, 2002)

Public Health Impacts(PHI) Model

•STUDY•POP •x

•BASE•RISK •x

•CHANGE

•IN ENV •x

•EXP-•RISK•COEF

F •=

•# ADD’L•PHIs IN

•FUTURE

Public Health Impacts(PHI) Model

•STUDY•POP •x

•BASE•RISK •x

•CHANGE

•IN ENV •x

•EXP-•RISK•COEF

F •=

•# ADD’L•PHIs IN

•FUTURE

Census 2000 county pop

Public Health Impacts(PHI) Model

•STUDY•POP •x

•BASE•RISK •x

•CHANGE

•IN ENV •x

•EXP-•RISK•COEF

F •=

•# ADD’L•PHIs IN

•FUTURE

1990-1999 average annual

non-heat-rel mortality risk

Public Health Impacts(PHI) Model

•STUDY•POP •x

•BASE•RISK •x

•CHANGE

•IN ENV •x

•EXP-•RISK•COEF

F •=

•# ADD’L•PHIs IN

•FUTURE

(# days > MMT range)* (average #degrees F above

MMT range on those days)

Source: R Goldberg & C Rosenzweig, NASA-GISS

Public Health Impacts(PHI) Model

•STUDY•POP •x

•BASE•RISK •x

•CHANGE

•IN ENV •x

•EXP-•RISK•COEF

F •=

•# ADD’L•PHIs IN

•FUTURE

1.305% increase RR mortality per

deg F>MMT range (“hot

slope”)

Public Health Impacts(PHI) Model

•STUDY•POP •x

•BASE•RISK •x

•CHANGE

•IN ENV •x

•EXP-•RISK•COEF

F •=

•# ADD’L•PHIs IN

•FUTURE

Additional # impacts (e.g. deaths) from env

change

NYC “optimal mortality temperature range” ~ 53.14 F – 73.54 F

from Curreiro et al. (2002 revision, ms. submitted)

Rel

ativ

e R

isk

of

Mor

talit

y

Average Daily Temperature (deg F)

NYCHP, Phase I: Preliminary Heat-Mortality Results Summers: Observed 1990s vs. GISS-modeled 2050s

Population Growth consistent with IPCC A2 & B2 scenarios*

In a typical SUMMER(June 1 - August 31):

1990s GISS A2 2050s GISS B2 2050s

Regional non-temperature-related deaths, all internal causes

42,117 64,509 52,312

Regional population 21,491,898 32,917,889 26,694,229

# Heat-related deaths 1,734 4,759 3,272

% Heat-related vs. Same-yrnon-temperature-related deaths

4.1% 7.4% 6.3%

# Additional heat-related deaths, 2050s vs. 1990s

3,025 1,538

% Increase above 1990s heat-related deaths

174.5% 88.7%

Heat-related mortality risk in regional population

8.1/100K 14.5/100K(6.4/100 K incr)

12.3/100K(4.2/100K incr)

* Regional population growth consistent with B2 population growth projections in 5-yr steps from 1990 to 2100 by Stuart Gaffin & Xiaoshi Xing (CIESIN, 2002); same for A2 population growth projections by Wolfgang Lutz at IIASA (CIESIN, 2002)

Precipitation ProjectionsPrecipitation Projections

• Global average water vapor and global mean Global average water vapor and global mean precipitation will increaseprecipitation will increase

• Larger year to year variations in precipitationLarger year to year variations in precipitation

Projected Changes in Annual Precipitation for the 2050sProjected Changes in Annual Precipitation for the 2050s

Source: The Met Office. Hadley Center for Climate Prediction and Research

The projected change is compared to the present day with a ~1% increase per year in equivalent COThe projected change is compared to the present day with a ~1% increase per year in equivalent CO 22

Change in Phenomenon Confidence in projected change*

Increase in tropical cyclone peak wind and precipitation intensities Likely, over some areas

Increased summer continental drying & associated risk of drought

More intense precipitation events

Increase of heat index

Higher minimum temperatures, fewer cold days and frost days

Higher maximum temperatures, more hot days

Likely, over most mid-latitude continental interiors

Very likely, over most areas

Very likely, over many areas

Very likely

Very likely

Extreme EventsExtreme Events

*Judgmental estimates of confidence by IPCC: *Judgmental estimates of confidence by IPCC: very likelyvery likely - 90-99% chance, - 90-99% chance,likelylikely - 66-90% chance. - 66-90% chance.

Source: IPCC TAR 2001

• Global average sea level is Global average sea level is projected to rise by 4 to 35 inches projected to rise by 4 to 35 inches between 1990 and 2100between 1990 and 2100

• Projected rise is slightly lower Projected rise is slightly lower than the range presented in the than the range presented in the SAR (6 to 37 inches)SAR (6 to 37 inches)

• Sea level will continue to rise for Sea level will continue to rise for hundreds of years after hundreds of years after stabilization of greenhouse gas stabilization of greenhouse gas concentrationsconcentrations

Sea-Level Rise ProjectionsSea-Level Rise Projections

Source: IPCC TAR 2001

Sea-Level Rise CommitmentSea-Level Rise Commitment

Thermal expansion and land ice melt after an initial 1% increase in COThermal expansion and land ice melt after an initial 1% increase in CO22 for 70 years for 70 years

Source: The Met Office. Hadley Center for Climate Prediction and Research

Jim Hansen’s View (NASA/GISS)

1. Climate is Changing (Global Warming)

2. Human (Greenhouse Gas) Role is Probable

3. Global Warming Increases Hydrologic Extremes

(droughts/fires and heavy rain/floods)

4. With Large Climate Change, Detrimental Effects

Probably Exceed Beneficial Ones

5. Common Sense Steps to limit emissions are

warranted

6. Steps also to reverse CO2 trends (sequestration)

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Discussion question

What should we do?Nothing, it’s a hoax.

Wait until climate change is certain?

Take precautionary measures to reduce emissions?

Take drastic measures to reduce emissions?

Acknowledgement

For more information about UCS, visit <www.ucsusa.org>.