Why allergy season is so bad this year

Are your seasonal allergies worse than usual? If your eyes and throat are particularly itchy this year, you're not alone. Research has shown that climate change is making the North American pollen season worse, much to the chagrin of allergy sufferers. 

Why is the allergy season worse this year?

Seasonal allergies are usually a result of the body's response to airborne pollutants like pollen and mold which are more prevalent during the blooming season in spring, per The Wall Street Journal. These pollutants come from blooming trees and grasses following the winter. However, this year's mild winter has disrupted the usual seasonal schedule, writes The New York Times. "This winter, since it has been somewhat warm, the trees have been pollinating on the earlier side," Joyce Yu, a pediatric allergist-immunologist, told the Journal.

A 2021 study published in the journal Proceedings of the National Academy of Sciences found that pollen season has increased by approximately 20 days since 1990 and the concentration of pollen in the atmosphere has increased by 21 percent in North America. This pattern is expected to continue because of climate change. By the end of the century, the allergy season could be as much as 40 days longer than in recent decades, according to research published in the journal Nature.

On top of that, "this time of year, even people who don't have a history of seasonal allergies can be symptomatic," Yu continues. About a quarter of adults and 20 percent of children have officially been diagnosed with seasonal allergies, also known as hay fever, writes the Journal. Symptoms of hay fever include a runny or stuffed nose, itchy eyes, and skin, and sneezing. "Pollen can also trigger an asthma attack, which of course is much more serious for people that suffer from asthma," explained Lauren Casey, a meteorologist with Climate Central, to CNN. Experts warn that the increasing intensity of the allergy season could become a public health emergency in the future.

"For people who have been managing seasonal allergies for a long time, they may have already noticed allergy symptoms starting earlier, lasting longer, and being more intense than even a few years ago," Kenneth Mendez of the Asthma and Allergy Foundation of America remarked to the Times.

How else is climate change affecting allergy season?

Climate change is causing average global temperatures to increase over time, which in turn is shortening winters and extending the spring season. Spring is also known as the growing season, which is when plants begin to bloom once again. "Because of climate change, we're now seeing an earlier and longer growing season for plants, which of course make pollen," Casey told CNN.

Trees and other plants use sunlight, rainfall, and temperature to judge when to come out from their dormant positions in the winter and begin blooming, CBS News writes. "They're called 'degree days,' but it's not temperature, it's a heat unit. When that number has been reached, those leaves will push out," explained Val Cervenka of the Minnesota Department of Natural Resources to CBS. "When they get what they need, they'll leaf out and they'll bloom."

Pollination is an important process for plants to reproduce, but the earlier spring could disrupt "the whole chain of the ecosystem" because "the difference between flowering times and pollinator emergence could lead to certain plants and trees not being pollinated," according to Clara Holmes of the New York Flora Association.

Climate change is caused by an increased concentration of greenhouse gases in the atmosphere, which trap and hold heat. Carbon dioxide is one of those gases, and it's released in heavy quantities due to fossil fuel extraction and burning. However, carbon dioxide also serves an important role in pollinating plants by helping them "grow bigger and faster, flower more, and produce more pollen per flower," per the Journal​​​​​​. With more pollen comes worse allergic reactions.

Combating climate change is necessary to stop the season from continuing to stretch longer. As Theresa Crimmins of the National Phenology Network at the University of Arizona remarked: "What we're seeing this year can give us a flavor of what is likely to continue to occur at varying intervals if we globally are not able to reduce emissions." Stock up on those tissues.