Allergic to ragweed?

Local researchers predict that climate change is likely to make things worse

  • Ragweed plants can produce pollen when they’ve reached only a couple of inches in height says plant ecologist Kristina Stinson, but some more productive specimens can grow very tall, as illustrated by this plant overtopping an elementary school boy. Stinson’s research suggests that climate change may allow common ragweed to extend its growing range northward and into major northeast metro areas in coming years. Contributed photo/Kristina Stinson

  • Ragweed plants can produce pollen when they’ve reached only a couple of inches in height, says plant ecologist Kristina Stinson, but some more productive specimens can grow very tall, as illustrated by the plant, at right, overtopping her son, Sebastian Stinson.

  • ragweed isolated on white background closeup Zan Valerii—Getty Images/iStockphoto

Published: 11/27/2018 11:22:25 AM

After last week’s snowfall, allergy season is probably the last thing on anyone’s mind. But a paper recently published by researchers at the University of Massachusetts Amherst — analyzing the impact of climate change on ragweed — may change that.

As the climate warms, Kristina Stinson, a plant ecologist and associate professor at the Amherst university, says ragweed — a common allergen and plant found throughout New England — will expand further into the northeast and increase in density in areas where it already grows, such as western Massachusetts.

“One reason we chose to study ragweed is because of its human health implications. Ragweed pollen is the primary allergen culprit for hay fever symptoms in summer and fall in North America, so it affects a lot of people,” Stinson said. “Ragweed is very abundant already in the Pioneer Valley.”

According to Stinson’s research predictions, ragweed is projected to expand drastically northward into major northeast metro areas. By the 2050s, the model predicts that ragweed could be prevalent in the vast majority of states between Virginia and Maine. Currently, there are much smaller pockets of ragweed throughout that same region.

Stinson’s research, which she completed over a number of years with co-author Michael Case of the University of Washington, was published in the scholarly journal “PLOS One.” Funding came from the U.S. Environmental Protection Agency and the Amherst university’s Department of Environmental Conservation.

In order to calculate their findings, Stinson says they made a map of where ragweed grows and interpolated that into various climate change models to create a single ragweed prediction model. 

Besides becoming more prevalent, Christine Rogers, adjunct associate professor in Environmental Health Science and president of Pan American Aerobiology Association, said that as carbon dioxide levels increase, ragweed plants produce more pollen.

“If we double the amount of carbon dioxide plants are exposed to, they’re going to produce roughly 50 percent more pollen,” Rogers said. “It will cause the people who have allergies to have worse symptoms.”

But while it's known that more pollen exacerbates the symptoms of those who already have allergies, Rogers, who published an earlier research paper on carbon dioxide levels in ragweed in 2006, noted it’s not yet known if more pollen will make more people develop allergies. In the future, Rogers said she's interested in studying whether or not this might be the case.

“What’s exciting about the study is that we were able to pinpoint where those expansions might be to get a more detailed picture,” she said. “We zoomed in on 700 data points for ragweed from all across its range in North America, and paired that information with another database that specifies climate in each of those exact locations. We then used climate change models to project forward in time what might be expected to occur.”

While Stinson’s research was focused on how the future climate impact where ragweed grows, she noted the study’s findings could be helpful to public health professionals to lesson the impact of climate change on those with allergies or asthma.

“It allows public health planners to be aware that it’s possible there will be more ragweed in future landscapes,” Stinson said. 

Many people who have asthma have symptoms that are triggered by allergies, said Sarita Hudson, director of programs and development at the Public Health Institute of Western Massachusetts. She noted that climate change research, such as that completed by Stinson and Case, is important because it can help everyone prepare for exacerbated allergies.

“We know that with climate change there will be increased pollen. The growing season will be longer,” she said. On a practical level, she noted that research can “help people understand that ‘yes, my allergies will be worse.’ ”

“Do I need to be taking my asthma medications? Do I need to be taking my allergy medications? Can we grow trees that won’t have the same impact? Are there landscaping efforts we can make so that it doesn’t have the same impact?” she said.

Andy Castillo can be reached at

Daily Hampshire Gazette Office

115 Conz Street
Northampton, MA 01061


Copyright © 2021 by H.S. Gere & Sons, Inc.
Terms & Conditions - Privacy Policy