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)