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University Relations

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Dec. 20, 2005
Contact: Johannes Feddema, associate professor of geography, (785) 864-8860.

KU professor finds land use can contribute to global warming, climate change

LAWRENCE -- Deforestation in the Amazon could possibly lead to climate changes in Kansas and contribute to global warming, according to new research by a University of Kansas professor.

"We're trying to get the climate change community to look at more than just global warming," said Johannes Feddema, KU associate professor of geography.

Feddema was the lead author of the research published in the Dec. 9 issue of Science in an article titled "The Importance of Land Cover Change in Simulating Future Climates." Feddema worked with six other scientists from the National Center for Atmospheric Research, based in Boulder, Colo., while there on sabbatical for a year.

The article examines two different scenarios for greenhouse gas emissions and land cover projections set forth by the Intergovernmental Panel on Climate Change.

The first scenario assumes fossil fuels will not be depended upon as heavily in the future, and fuel efficiency will greatly improve, thereby reducing greenhouse gas emissions. The second, more pessimistic scenario, assumes fossil fuel use and greenhouse gas emissions will increase steadily. The more pessimistic scenario showed that deforestation in the Amazon could lead to about a 2-degree Celsius increase in surface temperature across the Amazon by 2100 in addition to the 2-degree increase that is already expected. That rate is about double what could be expected without deforestation, Feddema said.

Converting land to crops in some areas can actually cool the environment. Heating or cooling of a regional climate is due to albedo, or the amount of sun energy land absorbs or reflects. Land that is converted to crops reflects more sunlight and puts more moisture into the air.

Feddema's study found that land use scenarios probably would not greatly affect average global temperatures, as different regions' changes tend to cancel each other out.

The study calculated climate changes by plugging land use patterns into a computer model of the earth's climate. The numbers were analyzed for more than a year by some of the world's most sophisticated computers to come up with analyses up to 2100.

Climate change has been studied for many years, but the work of Feddema's team was the first to incorporate land cover and ocean temperature in a fully coupled global climate model. Previous studies assumed a constant temperature for oceans. This land cover study took into account the interactions between land and atmospheric processes as well as feedbacks to ocean conditions.

"We turned everything on and that's what's unique about our study," Feddema said.

Changes in one part of the globe can also have an effect on the climate thousands of miles away. For example, the Amazon deforestation appears to impact surface temperature over the tropical Atlantic and Pacific oceans affecting El Nino conditions and potentially the gulf stream. Through these interactions, land cover change in the Amazon could create wetter climates in areas such as Arizona and Colorado, Feddema said.

"That was one of our major findings, that land cover change in one area can cause climate change in another area," Feddema said.

The findings of the study are significant, but Feddema said the work is not finished. This study was the first to show the team's findings, and Feddema said he hopes it brings land cover issues to the attention of international policy makers on global warming.

"We're trying to show that land cover is important and more work needs to be done," he said.


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