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Global climate change

Common allergen expected to expand northward through the eastern U.S. under climate change

By Brett Anderson, AccuWeather senior meteorologist
11/09/2018, 12:04:58 PM

New research from the University of Massachusetts and the University of Washington indicates that ragweed, which is one of the most common sources of allergic reactions for people, will shift northward through the Northeast United States as the climate warms through the rest of this century.


Ragweed is a native plant in North America that typically grows in open areas. During the late summer and fall, the plant produces a fine-powder pollen that is easily distributed through the air by the wind. This pollen is responsible for the many symptoms associated with hay fever, including headaches, sneezing, runny noses, itchy eyes and throats.

In order to conduct this study, the research team built a machine learning model that incorporated 726 observations of common ragweed in the eastern U.S.

Excerpt below from the University of Washington News.....

By the 2050s, under a high-emissions scenario, the bright blue areas (see map above) will be newly populated with ragweed according to most climate models, and orange areas will have significantly less ragweed according to most climate models. Lighter blue shows that some of the 13 climate models predict expansion, while brown shows that some of the models predict a contraction. Gray is where ragweed is not present, and black indicates no change. Image credit Michael Case/University of Washington.

The study also found areas such as central Florida and the southern Appalachians where ragweed that is prevalent today will decline substantially in the future.

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Global climate change