Guest essay by Eric Worrall

University of Michigan models suggest that increased rates of plant growth due to warmer temperatures will boost pollen allergies.

Pollen season is getting longer and more intense with climate change – here’s what allergy sufferers can expect in the future

Published: March 16, 2022 3.08am AEDT

Yingxiao Zhang
Ph.D. Student in Atmospheric Science, University of Michigan

Allison L. Steiner
Professor of Atmospheric Science, University of Michigan

Brace yourselves, allergy suffers – new research shows pollen season is going to get a lot longer and more intense with climate change.

Our latest study finds that the U.S. will face up to a 200% increase in total pollen this century if the world continues producing carbon dioxide emissions from vehicles, power plants and other sources at a high rate. Pollen season in general will start up to 40 days earlier in the spring and last up to 19 days longer than today under that scenario.

As atmospheric scientists, we study how the atmosphere and climate affect trees and plants. While most studies focus on pollen overall, we zoomed in on more than a dozen different types of grasses and trees and how their pollen will affect regions across the U.S. in different ways. For example, species like oak and cypress will give the Northeast the biggest increase, but allergens will be on the rise just about everywhere, with consequences for human health and the economy.

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How much pollen is produced depends on how the plant grows. Rising global temperatures will boost plant growth in many areas, and that, in turn, will affect pollen production. But temperature is only part of the equation. We found that the bigger driver of the future pollen increase will be rising carbon dioxide emissions.

The higher temperature will extend the growing season, giving plants more time to emit pollen and reproduce. Carbon dioxide, meanwhile, fuels photosynthesis, so plants may grow larger and produce more pollen. We found that carbon dioxide levels may have a much larger impact on pollen increases than temperature in the future.

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Read more: https://theconversation.com/pollen-season-is-getting-longer-and-more-intense-with-climate-change-heres-what-allergy-sufferers-can-expect-in-the-future-179158

The abstract of the study;

Published: 15 March 2022

Projected climate-driven changes in pollen emission season length and magnitude over the continental United States

Yingxiao Zhang & Allison L. Steiner 

Nature Communications volume 13, Article number: 1234 (2022) Cite this article

Abstract

Atmospheric conditions affect the release of anemophilous pollen, and the timing and magnitude will be altered by climate change. As simulated with a pollen emission model and future climate data, warmer end-of-century temperatures (4–6 K) shift the start of spring emissions 10–40 days earlier and summer/fall weeds and grasses 5–15 days later and lengthen the season duration. Phenological shifts depend on the temperature response of individual taxa, with convergence in some regions and divergence in others. Temperature and precipitation alter daily pollen emission maxima by −35 to 40% and increase the annual total pollen emission by 16–40% due to changes in phenology and temperature-driven pollen production. Increasing atmospheric CO₂ may increase pollen production, and doubling production in conjunction with climate increases end-of-century emissions up to 200%. Land cover change modifies the distribution of pollen emitters, yet the effects are relatively small (<10%) compared to climate or CO₂. These simulations indicate that increasing pollen and longer seasons will increase the likelihood of seasonal allergies.

Read more: https://www.nature.com/articles/s41467-022-28764-0

For starters, I’m pretty sure allergies will not be a problem in the future. Medicines today are far better than what was available when I first developed symptoms. I would be very surprised if allergies are still a significant issue a few decades from now, let alone by the end of the century.

But there is a more immediate counter to this claim. As an asthmatic who also suffers pollen allergy, I have personally observed this issue is more complex than the scientists are suggesting.

There is a reason older people move to warm places like Florida or Queensland, even if they are asthmatic or have allergies.

When I moved from cold Britain to the Australian subtropics, my allergies became easier to manage.

Why? Even though the pollen season is longer in my new home, it seems more spread out.

The pollen explosion in cold places like Britain tends to be short duration but extremely intense. It has to be intense, because the growing season is short. Pollination for many plants must occur right at the start of the growing season, or fruits and seeds might not mature fast enough to be ready before the frost arrives.

In warmer places, there is much less pressure on plants to seize every precious day of growing season. Plants flower most of the year, and fruits like citrus comfortably continue growing through winter, usually maturing the following Spring.

Overall my experience is the move to a warmer climate helped me manage my asthma and hay fever. I encounter my other major trigger, cold air, a lot less frequently in Australia than I did in Britain. The reduced exposure to cold air, and the lack of violent changes in pollen exposure, makes it much easier to manage my asthma and hay fever with medications.