Study: Hay fever sufferers can blame global warming

August 15, 2000
Web posted at: 4:43 PM EDT (2043 GMT)

WASHINGTON (Reuters) -- Does your sneezing and hay fever seem to be getting worse each year? Blame global warming.

Researchers with the U.S. Agriculture Department said Tuesday that higher carbon dioxide (CO2) levels linked to gradually increasing temperatures on earth may also be responsible for doubling the amount of ragweed pollen during the past four decades.

Another doubling could occur by the end of this century, they said.

"This research may help us better understand the troubling impact of high carbon dioxide levels on our environment and our health," Agriculture Secretary Dan Glickman said in a statement.

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The USDA study showed pollen production rose almost 400 percent with a 200 percent increase in the amount of C02. The high CO2 levels also appeared to encourage ragweed to produce pollen earlier than usual.

Lewis Ziska, a USDA plant physiologist, measured pollen counts on ragweed grown in the laboratory at various levels of atmospheric CO2, from the 1900 level of 280 parts per million (ppm) to today's levels of 370 ppm, and at the future predicted level of 600 ppm.

Pollen production soared from 5.5 grams to 10 grams to 20 grams as CO2 moved through the three levels.

An estimated 40 million Americans suffer from allergies, mostly from airborne pollens such as ragweed, grass, spruce, cedar, juniper and other trees.

The U.S. Senate has yet to ratify the Kyoto Treaty, negotiated in late 1997 to curb global warming by limiting the fossil fuel emissions of industrialized nations. The emissions have been linked to the steady rise in carbon dioxide in the earth's atmosphere.

Copyright 2000 Reuters. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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United States Department of Agriculture

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