Does global warming exacerbate allergies? Think about the impact of "extended summers"- spring and autumn temperatures that are higher than normal on the flowering behavior of plants and weeds whose pollen make the lives of hundreds of thousands of individuals such a misery. In their report, "Sneezing and Wheezing: How Global Warming Could Increase Ragweed Allergies, Air Pollution and Asthma", the the natural resources Defense Council report that global warming will not only intensify smog, which also worsens asthma, it will also trigger ragweed to flourish and produce more pollen through direct exposure to carbon dioxide, global warming's leading pollutant.

New maps resulting from analysis by the Natural Resources Defense Council (NRDC) find that regions most affected by ragweed and smog substantially overlap with one another - leaving these regions particularly vulnerable to the effects of global warming. As global warming boosts levels of both ragweed and smog, the risk of asthma and allergic reactions for people living in these overlapping regions will likely increase.

"Our analysis reveals that there is a clear interplay between high levels of smog and ragweed that could lead to intensified reactions for both allergy and asthma sufferers," said Dr. Kim Knowlton, NRDC's global warming and health specialist. "People living in some of the most populated regions of this country may be feeling the effects of global warming every allergy season."

For further reading here are some documents for download (pdf files) from the NRDC:

• NRDC's full report (4MB)


• Fact sheet (400 KB)


• Map of Ozone and Ragweed Occurrence in the Continental United States (1.2 MB)