Scientists expect allergy seasons to continue to get worse with climate change


The current trajectory of seasonal allergies has significant implications for public health and well-being. Between 10% and 30% of the world’s population is affected by hay fever, and the prevalence is increasing. Photo by Mcfarlandmo/Wikimedia Commons

Scientists have long known that as the Earth warms due to climate change, plants produce more pollen, making allergy season longer and more pronounced.

Now, a new survey reveals that hay fever sufferers are becoming increasingly aware of it.

In a survey conducted by Harris Poll in partnership with HealthDay of more than 2,000 American adults, only 1 in 3 said they had received an official diagnosis of hay fever from a doctor, but 3 in 4 said they had experienced symptoms. seasonal allergies.

For most of these people, seasonal sneezing is no picnic – 74% said their symptoms had a negative impact on their overall quality of life. And according to Kathy Steinberg, vice president of the Harris Poll, “other points in the survey suggest that the situation will only get worse.”

As part of the survey, these approximately 1,500 respondents with allergies rated their level of agreement or disagreement with a list of statements, including:

  • “I feel like my seasonal allergies are getting worse every year.”
  • “My seasonal allergy symptoms have started earlier in the season for the past few years.”
  • “I now experience seasonal allergy symptoms all year round.”

In response to these statements, participants were divided. About half strongly or somewhat agreed with the statements, while the remainder strongly or somewhat disagreed.

“For many, their symptoms get worse every year, or they occur year-round, or they start earlier in the season than in recent years,” Steinberg said.

The trend towards longer and more intense pollen seasons is likely to become increasingly evident to those affected as global warming progresses.

“People who say [their allergies] seem to be getting worse, they could very well have more problems based on the scientific data we have on the increase in temperature and the increase in pollen,” Dr. Stanley Fineman said in a HealthDay Now interview. . Fineman is an allergist at Atlanta Allergy & Asthma and past president of the American College of Allergy, Asthma and Immunology.

“If we continue to have as many warming trends as we have, we’re likely to see higher and higher pollen counts, with seasons starting earlier,” he said.

In a recent studythe researchers modeled future pollen production and concluded that total pollen emissions could increase by up to 40% by 2100. They found that the spring pollen season is expected to start 10 to 40 days earlier, while the seasonal allergies in the fall will continue for up to 19 days. longer.

These escalations would add to existing increases in pollen production for decades. In 2018, the number of pollens was already 20% higher than in 1990, according to another study.

Higher temperatures, bigger flowers

According to William Anderegg, an associate professor of biology at the University of Utah, climate change has a dual effect on pollen counts: warmer temperatures and higher carbon dioxide emissions are the two drivers of production. pollen.

“The science linking climate change to longer and more severe pollen seasons is incredibly, incredibly clear. When you increase the temperature or increase the amount of CO2 in the atmosphere, plants tend to produce more pollen,” said Anderegg said. “They tend to get bigger and produce more pollen per plant.”

These by-products of human activity also shorten the winter and extend the growing seasons into spring and fall. Longer growing seasons give plants time to produce more pollen.

Fineman and his Atlanta firm have tracking daily pollen levels in the area for over 40 years. In 2021, they used this data to publish a study showing that oak pollen emissions have increased by 5% each year for the previous 27 years.

Fineman said he generally advises patients to start taking their allergy medications two weeks before the start of pollen season. And this date has come earlier and earlier over the years in accordance with the lengthening of the pollen season.

For many years it was around St. Patrick’s Day. Then it was Valentine’s Day. And in the past two years, pollen counts in the Atlanta area have spiked, causing it to notify patients around Groundhog Day.

These changes can confuse long-time allergy sufferers who are used to busting out antihistamines or getting their first immunotherapy shot at predictable times each year. Allergy treatments are generally most effective when started before symptoms appear.

When patients aren’t prepared, “that’s when things can go really wrong,” Anderegg said. “And I often hear that from allergists. Patients are caught off guard because pollen seasons start much earlier.”

The current trajectory of seasonal allergies has significant implications for public health and well-being. Between 10% and 30% of the world’s population is affected by hay fever, and the prevalence is increasing. For many, the condition is a significant burden with far-reaching effects. For example, more than 70% of allergy sufferers in the HealthDay/Harris Poll survey said their symptoms affected their ability to get a good night’s sleep.

The consequences of seasonal allergies and the increase in the number of pollens are also felt indirectly.

“There’s quite a large literature that links it to economic productivity, the ability of workers to do their jobs, and children,” Anderegg explained. “When the kids are hurting too, it’s really hard for them to learn and do well in school.”

Another economic ramification — medical care associated with pollen costs more than $3 billion each year, according to the US Centers for Disease Control and Prevention.

With the worsening and lengthening of the pollen season, several million people are now directly affected by the effects of climate change. Given the ubiquity of seasonal allergies, this trend presents an opportunity.

“There are very big benefits to addressing climate change proactively and urgently,” Anderegg said. “We can prevent about half of the increase in the pollen season from getting worse if we tackle climate change, maybe even more than that.”

More information

The United States Centers for Disease Control and Prevention have more about seasonal allergies and climate change.

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