1	Global Warming Dennis Hartmann Professor and Chair Department of Atmospheric Sciences University of Washington http://www.atmos.washington.edu/~dennis/
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3	Climate Change The composition of the atmosphere, and the Earth’s climate has changed, mostly due to human activities (highly certain), and is projected to continue to change, globally and regionally: Increased greenhouse gases and aerosols Warmer temperatures Changing precipitation patterns – spatially and temporally Higher sea levels – higher storm surges Retreating mountain glaciers Melting of the Greenland ice cap Reduced arctic sea ice More frequent extreme weather events heat waves, floods and droughts More intense cyclonic events, e,g., hurricanes in the Atlantic
4	Direct Observations of Recent Climate Change
5	Temperature Records (Deviation from 1951- 1980 mean)
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8	Ice Melt in Greenland
9	Climate Change Climate change is both a development and global environmental issue, which undermines: environmental sustainability poverty alleviation and the livelihoods of the poor human health personal, national and regional security Climate change is an inter- and intra-generational equity issue: developing countries and poor people in developing countries are the most vulnerable the actions of today will affect future generations because of the long life-times of the greenhouse gases and the inertia within the climate system
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11	Summer of 2003
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14	Hurricane Trends
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19	Climate Forcing is defined to be the change in the top-of-atmosphere energy budget caused by an action. Double CO2 ~ 4 Wm^-2 Volcanic Eruption ~ 2 Wm ^-2 Change solar output by 0.1% ~ 0.24 Wm^-2
20	Global-average radiative forcing estimates and ranges
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22	Human and natural drivers of climate change Annual fossil CO₂ emissions increased from an average of 6.4 GtCper year in the 1990s, to 7.2 GtC per year in 2000-2005 CO₂ radiative forcing increased by 20%from 1995 to 2005, the largest in any decade in at least the last 200 years ---------------------------------------------------------------------- Changes in solar irradiance since 1750 are exstimated to have caused a radiative forcing of +0.12 Wm^-2 Compared to 2.6 Wm^-2 for greenhouse gases carbon dioxide, methane and nitrous oxide.
23	Global-average radiative forcing estimates and ranges
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26	Observed widespread warming extremely unlikely without external forcing very unlikely due to known natural causes alone
27	Attribution are observed changes consistent with expected responses to forcings inconsistent with alternative explanations
28	Understanding and Attributing Climate Change Continental warming likely shows a significant anthropogenic contribution over the past 50 years
29	Ocean Heat Content & Sea Level
30	Projections of Future Changes in Climate
31	Projections of Future Changes in Climate
32	Some Areas are Projected to Become Wetter, Others Drier
33	Climate Change Human-induced climate change is projected to: Decrease water availability and water quality in many arid- and semi-arid regions – increased risk of floods and droughts in many regions (the Stern Report concluded that the fraction of land in extreme drought at any one time could increase from 1% to 30%) Decrease the reliability of hydropower and biomass production in some regions Increase the incidence of vector- (e.g., malaria and dengue) and water-borne (e.g., cholera) diseases, as well as heat stress mortality, threats nutrition in developing countries, increase in extreme weather event deaths Decrease agricultural productivity for almost any warming in the tropics and sub-tropics and adverse impacts on fisheries Adversely effect ecological systems, especially coral reefs, and exacerbate the loss of biodiversity
34	Projected Impacts of Climate Change
35	CO₂ Emissions by Sector and Fuel
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39	OECD and non-OECD shares 50-year view
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43	15 Ways to Make a Wedge
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46	Five ways to cut 1 tonC/yr in half
47	Directions for the World