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IPCC Intergovernmental Panel on Climate Change


IPCC Intergovernmental Panel on Climate Change Established by UN Environmental Program and the World Meteorlogical Society in 1988 Consists of 2000 experts in ... – PowerPoint PPT presentation

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Title: IPCC Intergovernmental Panel on Climate Change

IPCC Intergovernmental Panel on Climate Change
  • Established by UN Environmental Program and the
    World Meteorlogical Society in 1988
  • Consists of 2000 experts in appropriate fields
  • 3 working groups I assess the scientific issues
    II evaluate impact on global climate change III
    risk management and mitigation
  • Third Assessment January 2001
  • Fourth Assessment Feb 2007 was the point at which
    conclusive evidence convinced most that the
    climate is changing due to anthropogenic causes
    (debate ended overall besides in the political
    and economic arenas and a minority of skeptic

Atmospheric Structure
IPCC Assessments
  • Third Assessment 2001 Human activities are
    influencing global climate change
  • Fourth Assessment 2007
  • global climate change is now occurring
  • caused by rising levels of anthropogenic
    greenhouse gases
  • global impacts will be unprecedented and severe

Impacts of Global Warming
  • Melting of polar ice caps
  • Flooding of coastal areas
  • Massive migrations of people inland
  • Alteration of rainfall patterns
  • Deserts becoming farmland and farmland becoming
  • Significant losses in crop yields

The Earth as a Greenhouse
Greenhouse Gases and Sources ranked by highest
radiative forcing to lowest
  • Water vapor
  • CO2
  • Methane
  • Nitrous oxide
  • CFCs and other halocarbons
  • Hydrological cycle
  • fossil fuel, respiration
  • Animal husbandry
  • Chemical fertilizers
  • Refrigerants

contribute to ozone depletion in stratosphere
as well
Radiative Forcing (Watts/m2)positive forcing
leads to warmingnegative forcing leads to cooling
Radiative forces relates energy into vs. energy
leaving tropospherepositive forcing leads to
warmingnegative forcing leads to cooling
Sulfate aerosols result from chemical reactions
in the atmosphere of SO2 from fossil fuel burning
and have a short life in the air (so only
localized cooling effects)
Current CO2 levels are 387 ppm (or 387,000
ppb) 35 higher than before industrial revolution
and higher than any time in the last 400,000
years (see next slide) Thus our insulating
blanket is thicker and it is reasonable to expect
higher temperatures to follow Methane CH4 level
have more than doubled since before the
industrial revolution and likely more than in
last 400,000 yrs also
Global Carbon Cycle
Data is given in GtC (billion metric tons of
carbon). Carbon pools are in the boxes, and
fluxes are indicated by the arrows.
Evidences of Climatic Change
  • 17 of the hottest years on record have occurred
    since 1980 (Fig. 20-5)
  • Since mid 1970s, average global temp has risen
    0.6oC (1.1oF) and 0.8oC (1.4oF) over last century
    (remember 5oC swings between ice ages and warm
  • Wide-scale recession of glaciers
  • Dramatic temp. increases in northern latitudes
    and melting of permafrost
  • Sea level rising
  • Increased severity of extreme weather?
    (hurricanes, monsoons, flooding, droughts, etc)

IPCC Predicted mean global temperature change by
2100 is between 1.5 and 4.5 Co
(No Transcript)
Fourth Assessment CO2 Concentrations from Mona
Loa Observatory
Why seasonal variation (the wiggle in the graph)?
with CO2 rising in fall and winter and CO2
decreasing in spring and summer.
Comparison between actual temperature data (thick
black line) and the runs of 13 models shown in
The hockey stick curve of temp over last 1000
IPCC Report Model Projections of global mean
warming with various scenarios from commitment
where GHG
Climates in the Past
(No Transcript)
Key Findings of the Fourth Assessment
  • Increased warming climate change
  • Differing regional impacts
  • Heat waves more frequent and last longer
  • Vulnerable ecosystems - arctic
  • Widespread water concerns increase in extremes
    ( and -) of daily precipitation
  • Agriculture largely unaffected
  • Thermohaline conveyor system expected to slow
  • Rising sea levels
  • Storm intensities expected to increase

Arctic Climate Impact Assessment in 2004
  • Arctic climate is now warming rapidly (twice as
    fast as global mean and 4-7oC in next 100 yrs)
  • Arctic warming and its consequences will have
    worldwide implications
  • Arctic vegetation zones will shift, and animal
    ranges and distribution will change (aquatic and
  • Reduced sea ice and earlier seasonal melting
    likely to increase marine transport and access to
  • Thawing ice permafrost will disrupt
    transportation, buildings, and other

Decline of Arctic Sea Ice
Tracking sea ice at the end of northern summer by
satellite images.decline of more than 8 per
Arctic Albedo Feedback loop positive radiative
What About the Antarctic?
  • Holds most of the worlds ice
  • Could be a huge factor in future sea level rise
  • Although unlikely to fully melt, Greenland and
    Antarctic ice sheets hold enough water to raise
    sea level by 230 feetfor perspective
  • Losing as much as 36 cubic miles of ice/year
    enough to raise sea level by 0.4mm/year

Response I to Climate Mitigation
  • Framework Convention on Climate Change
  • Kyoto Protocol Copenhagen Climate Conf
  • U.N. Climate Control Conference
  • U.S. Policy
  • Global Climate Change Initiative
  • Climate Change Science Program
  • National Climate Change Technology Initiative

Response 2 Adaptation
  • Reduced crop yields
  • Water scarcity
  • Increased heat and moisture ? infectious diseases
    and lethal heat waves
  • Increased intensity and severity of storm events
  • Impoverished nations will be most affected
    adaptation not an option
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