Allergy season will be affected by climate change, scientists say
If you sneeze and sneeze more than you used to this allergy season, scientists may be able to explain why.
It’s the time of year when ragweed pollen is at its highest in the air, according to Dr. Robert Hertzler, emeritus professor of agriculture and expanded weed science at Iowa State University. He notes that as the days get shorter towards winter, ragweed is most likely to bloom, releasing the often allergenic pollen of common weeds into the air.
Studies have shown that over the past 40 to 50 years, the amount and potency of pollen produced by ragweed has increased, Hartzler said. Scientists are starting to realize that climate change is likely to be the culprit, he said.
More Pollen, More Problems
Dr. Luis Ziska, associate professor of environmental health sciences at Columbia University Irving Medical Center, said climate change will affect the growth rate of common allergens such as ragweed.
Ziska said carbon dioxide, which is being rapidly released into the atmosphere from fossil fuel emissions, is a resource plants need to grow. However, high levels of carbon dioxide in the atmosphere can have unusual effects on the growth of certain types of plants, he said.
“Increased CO2 can stimulate plant growth. One of the plants whose growth is stimulated is ragweed, as well as other plants that produce pollen,” he said.
Ziska said studies are beginning to show that carbon dioxide not only increases the amount of pollen in the atmosphere, but also enhances its allergen content.
“The proteins on the pollen surface are altered in such a way that they also increase the amount of allergens, the proteins that trigger an immune response,” he said.
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His research was conducted with researchers from the University of Utah School of Biological Sciences. They found that “human-induced climate change” was associated with “a significantly intensified pollen season in North America between 1990 and 2018.” Their study found that the pollen season began 20 days earlier and lasted 10 days longer than in 1990, and the amount of pollen released into the air was on average 21% higher.
This study builds on previous small-scale experiments that found a strong relationship between temperature and pollen counts. We collect data from over 60 pollen observatories nationwide. There are no observatories located in Iowa, but the data collected originate from nearby Omaha. Lacrosse, Wisconsin. and Kansas City, Missouri.
Applying statistical methods to a set of climate models, Ziska and his colleagues conclude that climate change alone can explain “about half the lengthening of the pollen season and about 8% of the increase in pollen abundance.” is ready.
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Pollen levels vary by location
Although the study relies on data collected from across the United States, Hartzler warns that daily pollen levels vary greatly from place to place.
The University of Iowa’s State Institute of Health tracked normal pollen levels, but stopped in 2013 due to state budget cuts. Hartzler said the task is difficult because measuring pollen at one location doesn’t always help predict levels at another location.
“If they were measuring Grimes’ location, the amount of pollen there wouldn’t really correlate at all with what’s at Ankeny or Newton,” he said. It’s how much ragweed is in your immediate vicinity that determines whether the pollen count is high.”
Therefore, people who don’t tend their lawns and building more or less fences around their fields can all contribute to the population of ragweed plants and, consequently, to the amount of ragweed pollen in the air. It’s a small action.
Hartzler said allergy season will likely last until mid-September. He admits that “you can’t really escape pollen,” but recommends that people with more sensitive allergies stay indoors in the morning when pollen concentrations tend to be at their highest.