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What have you heard?
Global WarmingGreenhouse Gases
Carbon Dioxide (CO 2)Fossil Fuels
Ice Core RecordsClimate Change
What have you heard?
Is Global Warming Fueling Katrina?
How one number touched off big climate-change fight at UW
Global warming could burn insurersActivists call on industry to act
Jellyfish creature the answer to global warming? www.Scienceblog.com
EXAGGERATED SCIENCE
How Global Warming Research is Creating a Climate of Fear
Research Links Global Warming to Wildfires In a Shift, White House Cites Global Warming as a Problem
Global warming causing new evolutionary patterns
Rise in wild fires a result of climate change
Seattle mayors' meeting a cozy climate for business
Seattle reports milestone in cutting emissions
Our Questions Today
Science of Climate Change• What are Greenhouse Gases?• How do they cause warming?• How are humans affecting the climate?
Science of Climate Change:What are Greenhouse Gases?How do they cause warming?How are humans affecting the climate?
UW Climate Impacts Group
GHE#1 - natural
Earth’s Natural Greenhouse Effect
GHE#2 - humansHuman-caused Global Warming
GHE#3 - textThe science of global warming is based on well-understood physical principles. There is NO scientific debate about this!
Due to human activities, there are now 40% more greenhouse gases in the atmosphere than there were a few hundred years ago.
The Earth has already warmed as the consequence of this, and scientists expect that the next 20 to 100 years the world will warm a lot more!
Greenhouse gases
GHG GHG
• Sunlight heats the earth
• Some of sun’s energy is reradiated from surface.
• GHGs absorb this energy
• GHGs reradiate some escaping energy back towards surface, making the temperature warmer
GHG
PCC slide no. 033
Most Important Greenhouse Gases
Source: U.S. EPA 2005
GHGs:• Water: H2O• Carbon Dioxide:
CO2
• Methane: CH4
Source Examples:Oceans, Rivers, Plants,
SoilCombustion, RespirationWetlands, Oceans,
Combustion, Animals
http://www.for.gov.bc.caPCC slide no. 034
Future climate change
Source: IPCC 2007PCC slide no. 008
Risks of future climate change
Source: IPCC 2001a
Possible threats:
• Ecosystem change
• Flooding of coastal communities
• Spread of diseases
• Increase of extreme weather events
More Evidence: Ice Cores
• Ice layers preserve information about each yearSources: NOAA, GISP2 websitesPCC slide no. 036
Sea Level Rise
1-5 meters in Bangladesh 7-8 meters in Florida
PCC slide no. 037
Carbon dioxide acidifies seawater
• CO2 and carbonate (which plankton use to make shells) combine in the ocean.
• The ocean is already more acidic than it was 50 years ago.
SEM photograph of E. huxSource: Alfred-Wegener-Institut
CO2 CO2
Ocean
Atmosphere
“shelled-critters”
Arctic Sea Ice (in September)
data from National Snow and Ice Data Center (Boulder, CO, USA)
2005
Canada
U.S.A.
Asia
Russia
Europe
Arctic Sea Ice (in September)
data from National Snow and Ice Data Center (Boulder, CO, USA)
2005
5.6million km2
sea ice edge,
where normally found
Arctic Sea Ice (in September)
data from National Snow and Ice Data Center (Boulder, CO, USA)
2005
5.6million km2
2007
4.3million km2
sea ice edge (where normally found)
Arctic Sea Ice (in September)
data from National Snow and Ice Data Center (Boulder, CO, USA)Year
‘78 ‘82 ‘86 ‘90 ‘94 ‘98 ‘02 ‘06
Size
(milli
on k
m2 )
9
8
7
6
5
4
2005
2007
Melting ice sheets Sea level rise
Greenland Ice Sheet
Sea Level Rise
• Melting of– Greenland Ice Sheet– Antarctic Ice Sheet– Glaciers and ice caps
• Expansion of heated (warm) sea water
2 - 4C warming by ~2100 0.18 - 0.59 meter rise in sea level
IPCC (2007)
“Climate is what you expect Weather is what you get”
• Weather: Characteristics of the atmosphere over a short period of time, usually no more than a few days.
• Examples: Current Temperature, Rainfall, Humidity, Solar radiation
• Climate: The statistics (eg. average) of weather over a long period of time.
• Examples: Average Temperature, Rainfall, Humidity, Solar radiation
Climate
Weather
Source: www-k12.atmos.washington.edu/k12/grayskies/
Mar Apr May Jun July Aug Sep Oct Nov Dec Jan Feb
Temperatures at SeaTac Airport for one year:
Deg
rees
Far
enhe
it
Climate Change v. Climate Variability
We see the sum of both
Climate variability (e.g. Natural swings)
Climate change (e.g. warming trend)
Time (years)
"clim
ate"
U.S.
186.1
EuropeanUnion
127.8Russia
68.4Ukraine
21.7Poland
14.4
China
57.6Japan
31.2
Australia
7.6
India
15.5
Kazakhstan
10.1
South Africa
8.5
Canada
14.9
Mexico
7.8Trinidad and Tobago
United Arab Emirates
Kuwait
Total CO2 emissions
Between 1950-2001 in billions of tons
TIME magazine, 2001
US: 4% of world’s total population
25% of the world’s greenhouse gases
China:25% of the world’s population
8.5% of the world’s greenhouse gases (since 1950)