Allergy seasons getting longer and more severe thanks to climate change

For many people, the beauty of spring is countered by the sneezing, runny nose and itchy eyes of allergies that come with the warmer weather. For those people, science has some bad news – climate change seems to be making pollen season longer and more severe.

The new study, led by scientists at the University of Utah, compiled almost 30 years of measurements from 60 pollen count stations across the US and Canada. They found that by 2018, the pollen season was starting 20 days earlier, lasting 10 days longer, and involving 21 percent higher pollen concentrations than in 1990.

The team says that tree pollen levels increased more than that of other plants, and Texas and the Midwestern US saw the highest increases in pollen counts.

So why are pollen levels going up? Perhaps unsurprisingly, the researchers link it to the warmer temperatures brought about by climate change.

“A number of smaller-scale studies – usually in greenhouse settings on small plants – had indicated strong links between temperature and pollen,” says William Anderegg, lead author of the study. “This study reveals that connection at continental scales and explicitly links pollen trends to human-caused climate change.”

To investigate that angle, the team used over 20 climate models and mapped them against the pollen trend data they collected. Through this, they found that climate change could account for about 50 percent of the lengthening of the pollen season, but only eight percent of the pollen amount increase.

It was also found that temperatures were the most important factor driving the increases. The warmer weather appeared to be affecting the biological clocks of plants, causing them to begin producing pollen earlier in the year. Interestingly, higher levels of carbon dioxide didn’t seem to have much of a direct impact on pollen levels, beyond being the driver of higher temperatures.

These kinds of allergies might seem trivial, but it's more than just a seasonal sniffle. Allergies can exacerbate conditions like asthma, increase hospital visits and potentially weaken a person's immune defenses against viruses.

“The strong link between warmer weather and pollen seasons provides a crystal-clear example of how climate change is already affecting peoples’ health across the US,” says Anderegg. “Climate change isn’t something far away and in the future. It’s already here in every spring breath we take and increasing human misery.”

The research was published in the journal Proceedings of the National Academy of Sciences.

Source: University of Utah