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Global climate change

Climate change impacts on spring allergies in the U.S.

By Brett Anderson, AccuWeather senior meteorologist
4/03/2019, 12:44:00 PM

New research published in the journal PLOS ONE shows how certain climate change-driven ecological changes are directly linked to allergic disease burden in the United States.

Just a relatively small change in the timing of tree flowering can have a significant economic impact, as it is estimated that 25 million American adults already suffer from hay fever each year, according to the University of Maryland News report.

The research team from the University of Maryland's School of Public Health found that seasonal hay fever increases when the timing of spring "green-up" changes.

Excerpt from the UMD report........

“We found that areas where the onset of spring was earlier than normal had 14% higher prevalence of hay fever,” said Associate Professor Amir Sapkota in the Maryland Institute for Applied Environmental Health. “Surprisingly, we also found similar risk in areas where the onset of spring was much later than what is typical for that geographic location,” he added.

The map below from the National Phenology Network shows the current status of the spring 2019 first leaf index, which shows locations that have reached the requirements for the Spring Leaf Index model so far this year. It appears that things are running a little behind schedule so far from the southern Plains to the Middle Atlantic this season.

The study also determined that the earlier onset of warmer, spring weather means trees flower sooner, which also causes a longer season of tree pollen, which is the major source of spring allergies. On the other hand, a very late start to spring due to lingering cold may cause many tree species to burst into bloom all at once, blasting allergy sufferers with a high concentration of pollen for a shorter period.

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or


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Global climate change