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Intergovernmental Panel on
Climate Change (IPCC)
• Established by the UN and World Meteorological
Organization in 1988
• Role of the IPCC: to assess the scientific,
technical, and socio-economic information
relevant for the understanding of the risks of
human-induced climate change.
• Assessments based on published and peerreviewed literature
Intergovernmental Panel on
Climate Change (IPCC)
• 2,500 of the world’s leading climate scientists and
technical experts contribute to reports
• Provides comprehensive and balanced
assessments of climate change science, impacts,
and adaptation and mitigation options
• Extensive peer-review and governmental review
ensures scientific credibility and policy relevance
Intergovernmental Panel on Climate Change (IPCC)
Plenary
IPCC Secretariat
WMO/UNEP
Switzerland
Working Group I
Climate change
science
Working Group II
Impacts,
adaptation and
vulnerability
Working Group III
Mitigation
Task force
on national
greenhouse gas
inventories
Technical support
unit (TSU) in
United Kingdom
TSU in
United States
TSU in
The Netherlands
TSU in
Japan
Experts, authors, contributors, reviewers
Source: Redrawn from Vital Climate Graphics
IPCC Assessment Reports
• Standard reference work
• First Assessment Report (FAR) - published in 1990
– Projected increase in temperature of 3 - 8 °F
– Consequences: rising sea levels, increase in extreme
weather events, serious pressure on aquatic and terrestrial
ecosystems
– “The size of the warming is broadly consistent with
predictions of climate models, . . . but the unequivocal
detection of the enhanced greenhouse effect from
observations is not likely for a decade or more.”
IPCC Assessment report foci
1990
1995
2001
IPCC Second Assessment
Report Conclusions
• Climate has changed over the past century
– Global mean surface air temperature has increased .5-1o F
– Global sea level has risen 4-10 inches
– Global precipitation over land has increased 1%
• “ Human signal still building . . . Nevertheless, the balance
of evidence suggests a discernible human influence on global
climate.”
IPCC Second Assessment
Report Conclusions
• Climate has changed over the past century
– Global mean surface air temperature has increased .5-1o F
– Global sea level has risen 4-10 inches
– Global precipitation over land has increased 1%
• “ Human signal still building . . . Nevertheless, the balance
of evidence suggests a discernible human influence on global
climate.”
• Climate is expected to continue to change in the future
– Projected temperature increase of 1.8-6.3oF by 2100
– Projected sea-level rise of 6-37 inches by 2100
– Likely increase in extreme weather events
Kyoto Protocol
• SAR provided key input to the negotiations
that led to the adoption of the Kyoto
Protocol in 1997
• Is an international agreement that
establishes binding targets for reduction of
greenhouse gases emitted by developed
countries.
Emission Scenarios
• SAR - used scenarios developed in 1992, known as
the IS92 series
• Alternative projections of population, affluence, and
technological change were used to come up with a
range of future GHG emission scenarios
• 1995 - IPCC evaluated the IS92 scenarios,
recommended that a new set of scenarios be
developed - Special Report on Emission Scenarios
• TAR - projections are underlain by the full range of
SRES scenarios
Third Assessment Report
of the IPCC
• Published in 2001
• Emphasizes information from the last 5
years
• Places climate change in the context of
sustainable development, emphasizing
equity issues
• Policy relevant, but not policy prescriptive
IPCC Third Assessment Report
Key Findings of Working Group I
“An increasing body of observations gives a
collective picture of a warming world and
other changes in the climate system.”
Variations of the
Earth’s Surface
Temperature*
*relative to 1961-1990 average
Source: IPCC TAR 2001
Global Annual Temperature Trends:
1901 - 1990
Source: Watson 2000
U.S. Temperature Trends: 1901 to 1998
Red circles = warming; Blue circles = cooling
All stations/trends displayed regardless of statistical significance.
Source: National Climatic Data Center/NESDIS/NOAA
U.S. Precipitation Trends: 1901 to 1998
Green • = increasing, Brown • = decreasing
All stations/trends displayed regardless of statistical significance
Source: National Climatic Data Center/NESDIS/NOAA
Extreme Precipitation Events in the U.S.
Source: Karl, et.al. 1996.
Increase in catastrophic flood events
Increase in frequency and
intensity of droughts
Source: OSTP
Snow cover and ice extent have decreased
Global average sea level has risen
and ocean heat content has increased
IPCC Third Assessment Report
Key Findings of Working Group I
“Emissions of greenhouse gases and aerosols
due to human activities continue to alter the
atmosphere in ways that are expected to
affect the climate.”
Indicators of the Human Influence
on the Atmosphere during the Industrial Era
Source: IPCC TAR 2001
IPCC Third Assessment Report
Key Findings of Working Group I
“Confidence in the ability of models to project
future climate has increased.”
IPCC Third Assessment Report
Key Findings of Working Group I
“There is new and stronger evidence that
most of the warming observed over the last
50 years is attributable to human
activities.”
IPCC Third Assessment Report
Key Findings of Working Group I
“Human influences will continue to change
atmospheric composition throughout the
21st century.”
IPCC Third Assessment Report
Key Findings of Working Group I
“Global average temperature and sea level
are projected to rise under all IPCC
scenarios.”
Main Findings of WG I
• Extensive and wide-spread evidence that the earth is warming;
we are already seeing the first clear signals of a changing
climate.
• Human activities are changing the atmospheric concentrations
of greenhouse gases.
• New and stronger evidence of a human influence on climate.
• Global temperature will rise from 2.5 to 10.4°F over this
century. Precipitation patterns will change, sea level will rise
and extreme weather events will increase.
• Human influence will continue to grow during the next century
unless measures are taken to reduce GHG emissions.
IPCC History: Evolution of
Our Knowledge
• FAR (1990): “The size of the warming is broadly
consistent with predictions of climate models, . . . but
the unequivocal detection of the enhanced greenhouse
effect from observations is not likely for a decade or
more.”
• SAR (1996): “The balance of evidence suggests a
discernible human influence on climate.”
• TAR (2001): “There is new and stronger evidence that
most of the warming observed over the last 50 years is
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
General Circulation Models
Governed by physics:
- Law of Continuity
- Equation of State
- Conservation of energy
- Conservation of momentum
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
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/
QuickTime™ and a
TIFF (Uncompressed) decompressor
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.
CO2 and SO2 in the 21st Century
Source: IPCC TAR 2001
Temperature Projections
Global average temperature
is projected to increase by
1.4 - 5.8°C by 2100
Projected temperature
increases are greater than
those in the SAR
Projected rate of warming is
unprecedented for last
10,000 years
Source: IPCC TAR 2001
Variations of the Earth’s Surface
Temperature - 1000 to 2100
1000AD to 1861, N.
Hemisphere, proxy
data
1861 to 2000, Global,
instrumental
2000 to 2100, SRES
projections
Source: IPCC TAR 2001
Projected Changes in Annual Temperatures for the 2050s
The projected change is compared to the present day with a ~1% increase per year in equivalent CO 2
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 sixfaced 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
Litchfield
Dutchess
Sullivan
New Haven
Putnam
Orange
Fairfield
Rockland
Sussex
Warren
Bergen
Morris
Suffolk
Bronx
Essex
New York
Hudson
Queens
Nassau
Kings
Union
Hunterdon
Westchester
Passaic
Richmond
Somerset
Middlesex
Mercer
Monmouth
Ocean
31 counties in 3 states (NY, NJ, CT)
21 million residents
13,000 square miles
Variety of pop densities & land uses
Estimated Increases in Ozone Excedences ( 1 hour >120 ppb)
for the New York Metro Region by 2050
1990 air
pollutant
emissions
2050 A2 air
pollutant
emissions
1990 Hottest
Summer
Climate
2050 A2
Hottest
Summer
Climate
786
3,266
(+315%)
1,745
(+122%)
7,489
(+749%)
(from C. Hogrefe et al, 2003)
Temperature & Mortality Relationship in 11 Eastern US Cities
(Curreiro et al, 2002)
Public Health Impacts
(PHI) Model
•STUDY
•POP
•x
•BASE
•RISK
•x
•CHANG
E
•IN ENV
•x
•EXP•RISK
•COEF
F
•=
•# ADD’L
•PHIs IN
•FUTURE
Public Health Impacts
(PHI) Model
•STUDY
•POP
•x
•BASE
•RISK
Census 2000
county pop
•x
•CHANG
E
•IN ENV
•x
•EXP•RISK
•COEF
F
•=
•# ADD’L
•PHIs IN
•FUTURE
Public Health Impacts
(PHI) Model
•STUDY
•POP
•x
•BASE
•RISK
•x
•CHANG
E
•IN ENV
•x
1990-1999 average
annual non-heatrel mortality risk
•EXP•RISK
•COEF
F
•=
•# ADD’L
•PHIs IN
•FUTURE
Public Health Impacts
(PHI) Model
•STUDY
•POP
•x
•BASE
•RISK
•x
•CHANG
E
•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
•CHANG
E
•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
•CHANG
E
•IN ENV
•x
•EXP•RISK
•COEF
F
•=
•# ADD’L
•PHIs IN
•FUTURE
Additional # impacts (e.g.
deaths) from env change
Relative Risk of Mortality
NYC “optimal mortality temperature range”
~ 53.14 F – 73.54 F
from Curreiro et al. (2002 revision, ms. submitted)
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
21,491,898
32,917,889
26,694,229
1,734
4,759
3,272
4.1%
7.4%
6.3%
3,025
1,538
174.5%
88.7%
14.5/100K
(6.4/100 K incr)
12.3/100K
(4.2/100K incr)
Regional population
# Heat-related deaths
% Heat-related vs. Same-yr
non-temperature-related deaths
# Additional heat-related deaths,
2050s vs. 1990s
% Increase above 1990s heatrelated deaths
Heat-related mortality risk in
regional population
8.1/100K
* 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 Projections
• Global average water vapor and global mean
precipitation will increase
• Larger year to year variations in precipitation
Projected Changes in Annual Precipitation for the 2050s
The projected change is compared to the present day with a ~1% increase per year in equivalent CO 2
Source: The Met Office. Hadley Center for Climate Prediction and Research
Extreme Events
Change in Phenomenon
Confidence in projected change*
Higher maximum temperatures,
more hot days
Very likely
Higher minimum temperatures,
fewer cold days and frost days
Very likely
Increase of heat index
Very likely, over most areas
More intense precipitation events
Very likely, over many areas
Increased summer continental
drying & associated risk of drought
Increase in tropical cyclone peak
wind and precipitation intensities
Likely, over most mid-latitude
continental interiors
Likely, over some areas
*Judgmental estimates of confidence by IPCC: very likely - 90-99% chance,
likely - 66-90% chance.
Source: IPCC TAR 2001
Sea-Level Rise Projections
• Global average sea level is
•
•
projected to rise by 4 to 35
inches between 1990 and
2100
Projected rise is slightly lower
than the range presented in the
SAR (6 to 37 inches)
Sea level will continue to rise
for hundreds of years after
stabilization of greenhouse
gas concentrations
Source: IPCC TAR 2001
Sea-Level Rise Commitment
Thermal expansion and land ice melt after an initial 1% increase in CO2 for 70 years
Source: The Met Office. Hadley Center for Climate Prediction and Research
Jim Hansen’s View
(NASA/GISS)
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
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)
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>.