Ragweed may boom with global warming

An experiment in which infrared heaters warmed ragweed on an Oklahoma prairie suggests that climate change actually is something to sneeze at.

Artificially warming a plot yielded extra ragweed plants, say Shiqiang Wan and his colleagues from the University of Oklahoma in Norman. The effect boosted pollen production 84 percent compared with unheated plots, the researchers report in the November 2002 American Journal of Botany.

Weather affects a particular year’s dose of misery from allergy-causing plants, but there hasn’t been much research into how global warming might affect such species.

The researchers set up a series of ragweed test plots and clipped some plots to simulate farmers’ mowing. Heaters warmed the air an extra 1.2C and boosted the soil temperature 1.8C in the unclipped patches and 2.7C in the clipped patches. The slight heating in both groups created a ragweed paradise. The ragweed expanded its coverage of warmed plots more than of unheated ones, regardless of clipping.

Global warming “could aggravate allergic hazards,” the researchers conclude.


If you have a comment on this article that you would like considered for publication in Science News, please send it to editors@sciencenews.org.

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.