Are seasonal allergies getting worse? Study says climate change may be the reason

SALT LAKE CITY – Climate change is making hay fever worse, a recent study suggests. The hay fever season is now about three weeks longer than it was 30 years ago. To make matters worse, there is also more than a fifth more pollen in the air today – and the amount is increasing, the researchers warn.

Global warming causes extra weeks of itching, sneezing and runny nose; another reason to reduce greenhouse gas emissions, say biologists. “The strong link between warmer weather and pollen seasons provides a clear example of how climate change is already affecting people’s health,” says lead author of the study, Dr William Anderegg of the University. from Utah, in a statement.

Scanning electron microscopy image of ragweed pollen. (Credit: University of Utah)

Warmer temperatures cause the internal time of plants, known as phenology, to start producing pollen earlier in the year. The traditional period spanned a little over a month, from mid-June to mid-July. The study found that pollen seasons now start about 20 days earlier than in 1990, ranging from March to September.

Allergies to airborne pollen can be more than just a seasonal nuisance, suggest the study authors. They are linked to respiratory health with implications for viral infections, emergency room visits, and even children’s school performance. More pollen lying around for a longer season makes these effects worse.

Global warming has been attributed to the burning of fossil fuels, the logging of tropical forests and the ranching of livestock. Greenhouse experiments show that increasing temperature and atmospheric carbon dioxide (CO2) – hallmarks of human-made climate change – can lead to increased pollen production.

Tests have also suggested that the worsening of the pollen seasons in some plant locations is due to rising temperatures. The study is the first to confirm this on a continent-wide scale.

“A number of smaller-scale studies – usually in greenhouses on small plants – had indicated strong links between temperature and pollen. This study reveals this connection on a continental scale and explicitly links pollen trends to man-made climate change, ”says Dr Anderegg.

The analysis is based on National Allergy Bureau measurements of airborne pollen and mold in the United States and Canada between 1990 and 2018. These were collected between 1990 and 2018 and manually counted by staff at 60 stations from both countries. Nationwide pollen quantities have climbed about 21 percent during the period. The largest increases have been recorded in Texas and the US Midwest, with trees being the main culprit.

Statistical calculations and nearly two dozen climate models have shown that global warming is responsible for about half of the lengthening of the season. It is also responsible for about 8 percent of the increase in pollen and the contribution of climate change to it is accelerating, the researchers said. This was demonstrated by dividing the years in half, 1990 to 2003 and 2003 to 2018.

“Climate change is not something distant and in the future,” adds Dr Anderegg. “It’s already there with every spring inspiration we take and increases human misery. The bigger question is: are we up to the challenge of meeting it? “

Hay fever is one of the most common allergies in the United States. About 19 million adults and just over five million children were diagnosed with hay fever in 2018. It is not life threatening, but can be debilitating, making even simple tasks difficult.

The study is published in Proceedings of the National Academy of Sciences.

SWNS writer Mark Waghorn contributed to this report.

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