Heather Price, Ph.D

Program on Climate Change

University of Washington

Global Climate Change

The science

• Thousands of peer-reviewed scientific papers• Intergovernmental Panel on Climate Change (IPCC)• Major peer reviewed reports in 1990, 1996, 2001,

2007• Conclusions:

– “An increasing body of observations gives a collective picture of a warming world and other changes in the climate system.”

– “There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.”

Temperature and CO2 vary together over glacial cycles

Source: Cuffey and Vimeux, Nature 412:523, 2001.

TemperatureCO2

Humans are altering atmospheric chemistry

Carbon dioxide (CO2): up 32% Methane (CH4): up 150%2004

Charles Keeling

Ralph Keeling

These changes are huge compared to the past

2011 CO2 = 390 ppmCarbon dioxide (CO2): up 32%

2004

Humans are altering atmospheric chemistry

Where in the world does CO2 come from?

2010 and 2005 tied for the warmest years on record. The 10 warmest years on record have all occurred since 1998. In the last century, Earth's lower atmosphere has warmed by more than half a degree Celsius (1.2 degrees F). Global sea level has risen 10 to 25 cm during the past 100 years, currently rising 0.08-0.12 inches per year (2.0-3.0 mm per year).

How has the climate already changed:

Source: Hadley Center http://www.met-office.gov.uk/research/hadleycentre/

1998

How has the world warmed?Greatest warming is occurring in Polar regions: Alaska, Greenland, Antarctica

Arctic ice thickness is down by 40%.

• Sea ice data acquired from submarines 1993-1997 and 1958-1976. • Mean ice thickness has decreased by 1.3 meters, from 3.1 to 1.6 meters.

Source: D.A. Rothrock, Y.Yu and G.A. Maykut, Thinning of the Arctic sea-ice cover, University of Washington, Seattle, 1999.

North Pole Sea Ice Extent Then and Now

1928

2000

The South Cascade glacier retreated dramatically in the 20th century

Courtesy of the USGS glacier group

Spruce Forests killed by Pine Beetle

Kenai Peninsula, Alaska:70 to 80 percent of the trees have died

Ask the scientists:

1. Have mean global temperatures risen compared to pre-1800s levels?

2. Has human activity been a significant factor in changing mean global temperatures?

• 90 percent of scientists said yes to the first question and 82 percent said yes to the second

• 97 percent of climate scientists said yes to both questions

• 47 percent of petroleum geologists said yes to the second question

Natural Climate Influence Human Climate Influence

All Climate Influences

By 2050 scientists expect 1 degree Celsius (2 degrees F) increase By 2100, climate models predict another 1.5-6 degree Celsius increase (3-11 degree F) Climate models also predict an additional 40-60 cm (~half meter) sea level rise by 2100 Sea level rise of 1 meter would endanger 90% of Japan’s sandy beaches

and much of Southern Florida, flooding Miami and the entire Everglades.

What do scientists predict for the future:

The main Northwest impact: less snow

April 1

Columbia

Basin

Snow

Extent

Impacts of hydrologic (water) changes

• Less snow, earlier melt means less water in summer – irrigation

– urban uses

– fisheries protection

– energy production

• More water in winter– energy production

– floodingNatural Columbia River flow at the Dalles, OR.

ChinaThe Bad News:• 80 % of energy from Coal• 16 of the worlds 20 most polluted cities• Respiratory illness is #1 killer in China• Pollution transports to Japan and beyond

The Good News:• Stronger fuel efficiency standards than USA: many US SUV’s will not be legal in China 2008• National law: at least 10% power from renewable energy by 2020 (same proposal was rejected by USA Congress last month)

Solar output varies - but not much

Figure courtesy of NOAA National Geophysical Data Center

Outline

• Observed changes in atmospheric composition• Understanding changes in global average

temperature• Global consequences of climate changes• Some issues here in the Northwest-loss of snow

pack• Policy dimensions… Why the ancient city of

Kyoto is a dirty word in middle America.

By 2000 Kilimanjaro: 82% of its ice had melted and is projected will be gone by 2015

Mt Kilimanjaro in 1912

Kilimanjaro, 2009