Are Seasonal Allergies Getting Worse Due to Climate Change?

Growing Seasons Are Getting Longer 

After the bitter cold and snowy winter that North Carolina (and indeed much of the nation) experienced, it makes sense that folks have been going outside to feel the warm sun, hear the birds sing, breathe in the sweet scents of the flowers … and SNEEZE! 

Again, again and again. 

And, regardless of how bad winter was, if you feel like those spring sneezing fits have been happening earlier over the past several years, you’re right. 

In an interview with NPR, Lew Ziska, an associate professor at the Mailman School of Public Health at Columbia University, said in some areas of the country, climate change is adding two to three weeks to the growing season and, by extension, the pollen season. 

“As things start earlier in the spring and go longer in the fall because of the warmer weather, that results in a longer pollen season,” said Ziska. 

The warming climate lengthens the country’s frost-free season, the time between the final 32°F reading in the spring and the first 32°F reading in the fall. As you might guess, during that time, plants can produce blossoms and sprouts without the risk of frost damage. That also means there’s more time for honeybees and other pollinators to collect nectar and distribute pollen. 

In fact, the growing season has expanded by at least 11 days in most of the country. That’s not a bad thing. But if you have allergies, all that extra growing time means pollen-sensitive people will be feeling the effects earlier in the spring and later in the fall. 

A longer growing season—and more pollen 

With warm temperatures dominating more of the year, the amount of pollen and the length of pollen season increase. Findings from the Centers for Disease Control and Prevention show that about 26% of adults and 19% of children have seasonal allergies.  

Ziska added that the warmer and longer growing season is making some pollen more potent. 

“The thing that makes pollen allergenic are the proteins on the surface of the pollen,” Ziska told NPR. “And what we found was that the concentration of that particular pollen protein was increasing in the case of two plant species that we know are very allergenic—one is oak, and the other one is ragweed.” 

And there’s one other thing to keep in mind. 

The increasing amounts of carbon dioxide in the atmosphere also mean plants will produce more pollen. That’s because of how a plant’s male sex organs, which produce pollen, react to carbon dioxide exposure. 

If there is more carbon dioxide in the atmosphere, plants don’t need to use as much energy to take in carbon dioxide for photosynthesis. They can instead use that energy to produce more pollen. Data shows that between 1990 and 2018, the amount of pollen in the atmosphere increased by 21% across North America.  

Advice to help with allergy season 

So, whether your allergy symptoms are getting worse or new allergy symptoms are suddenly kicking in, here’s some advice: 

• If you take an antihistamine during pollen season, start taking it one to two weeks earlier than you have in the past.
• If you have a HEPA air filter or an air purifier, use it.
• If you spend a lot of time outdoors, wash your clothes when you come in. Pollen can stay on your clothes and spread around your house.
• Watch the weather forecast and stay inside as much as possible on high-pollen days.

While pollen is not good for allergy sufferers, it is vital to our food supply. To look at the good side of pollen, watch this Sci NC story.