New research illuminates yet another deleterious health effect we can expect from climate change: more severe and prolonged allergy seasons. A study published in the journal Nature this month predicts that by the end of the century in the U.S., the amount of pollen plants release into the air is going to increase dramatically—as much as 200%—and that pollen season is going to become weeks longer.
Scientists have already established a connection between changes in the climate and changes in pollen emissions. A 2021 study published in Proceedings of the National Academy of Sciences found that from 1990 to 2018, North American pollen concentrations rose by about 21% and pollen seasons became about 20 days longer. We also know that the effects of climate change (including changes in air temperatures, rain patterns, and levels of carbon dioxide in the atmosphere) can influence not only our levels of pollen exposure, but also the risk of experiencing allergy symptoms and the severity of the effects pollen can have on our health, according to the Centers for Disease Control and Prevention (CDC).
This new paper looks at how that worrisome connection may play out in the future as climate change continues. Changes in temperatures and rain patterns will increase the daily maximum amounts of pollen emissions by about 35% to 40% and annual pollen emissions by about 16% to 40% by the end of the century, according to the paper. Factoring in future carbon dioxide emissions makes the picture look much bleaker, increasing pollen production up to a staggering 200% throughout the U.S. The simulations also showed that springtime emissions will start 10 to 40 days earlier, and that summer and fall emissions will start 5 to 15 days later—lengthening the duration of allergy season on both ends.
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The researchers made their predictions by using data modeling to simulate how climate change will affect the production of 15 different kinds of pollen in various regions of the U.S. They looked into how climate change is predicted to affect the local weather patterns (like temperature and precipitation), as well as the growth cycles and pollen seasons of the local plant life.
Generally speaking, the northern part of the country is expected to see the biggest shifts in pollen season, in accordance with bigger temperature increases. And the precise effects will not be uniform throughout the U.S. Modeling indicates that in the Northeast, for instance, rising temperatures and carbon dioxide emissions mean that tree species that have traditionally produced pollen on a more staggered timeline will increasingly see their pollen seasons overlap with one another (meaning the simultaneous pollen load in the air will be greater). In the Southeast, pollen from grasses and weeds is predicted to significantly increase, while in the Pacific Northwest, the height of allergy season may shift forward about a month because of the pollination cycle of alder trees.
The study authors also discussed the causes behind this phenomenon. One is a rise in temperature: Higher temperatures generally result in a longer growing season, which means plants will be producing pollen for more days out of the year. The other factor is carbon dioxide emissions, the primary source of greenhouse gas in the U.S., according to the U.S. Environmental Protection Agency. The researchers found that carbon dioxide emissions are likely to have a much more significant effect on pollen production compared to temperature. Carbon dioxide fuels photosynthesis (the process in which plants use sunlight, carbon dioxide, and water to make food for themselves and grow), and plants that grow larger tend to emit more pollen. So as carbon dioxide levels in the atmosphere rise, so too will pollen production.
Source: SELF
