Climate change to make the pollen season more unpleasant

Climate change has already made the allergy season longer and pollen counts higher, but you have not sneezed anything yet.

Climate scientists at the University of Michigan looked at 15 different plant pollen in the United States and used computer simulations to calculate how much worse the allergy season is likely to be in the year 2100. That’s enough to make allergy sufferers even more red-eyed.

As the world warms, the allergy season will start weeks earlier and end many days later – and it will be worse while it lasts, with pollen levels that may as much as triple in some places, according to a new study Tuesday in the journal Nature Communication.

Warmer weather allows the plants to start flowering earlier and keeps them from blooming later. Meanwhile, additional carbon dioxide in the air from burning fuels such as coal, gasoline and natural gas plants helps produce more pollen, said study co-author Allison Steiner, a climate researcher at the University of Michigan.

It’s already happening. A study a year ago from various researchers showed that from 1990 to 2018, pollen has increased and the allergy season starts earlier, with much of it due to climate change.

Allergy sufferers say the pollen season in the United States used to start around St. Patrick’s Day and now often starts around Valentine’s Day.

The new study showed that the allergy season would extend even further and the total amount of pollen would increase in the air. How long and how much depends on the pollen in question, the location and how much greenhouse gas emissions are put into the air.

With moderate cuts in greenhouse gas emissions from coal, oil and natural gas, the pollen season would start 20 days earlier at the end of the century. In the most extreme and increasingly unlikely warming scenario, the pollen season in large parts of America will start 40 days earlier than when it has generally started in recent decades.

Already, about 30% of the world and 40% of American children suffer from pollen allergy, which damages the economy through lost work days and medical costs, says climate researcher Yingxiao Zhang from the University of Michigan, lead author of the new study.

Allergies are especially difficult for the 25 million Americans with asthma. This could make the problem much worse for them, said Amir Sapkota, a professor of environmental health at the University of Maryland who was not part of the research.

While allergy disorders will increase throughout the United States, the Southeast will be hardest hit, Steiner said.

The start of the pine tree pollen season will move most dramatically, a problem in the Northwest Pacific. Cypress tree pollen – which is particularly bad in Texas – will see among the biggest increases.

Ambrosia and grasses – common pollen allergies – will also have longer seasons and higher pollen counts in the future, Zhang said.

The University of Michigan team’s projection projects would be about twice as big a leap in pollen problems as it has been since 1990, said University of Utah biologist and climate researcher Bill Anderegg.

“Overall, this is an incredibly important study,” said Anderegg, who was not involved in the new research. “It tells us that the historical trends with longer and more severe pollen seasons are likely to continue, driven by climate change, and this will definitely have significant health consequences for allergies and asthma for Americans.”


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Follow Seth Borenstein on Twitter at @borenbears.


The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. AP is solely responsible for all content.

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