Pollen alert: Climate change extends allergy season worldwide
Climate change is causing an increase in pollen levels, leading to a rise in seasonal allergies. Experts warn that extreme allergic events may occur more frequently.
Pollen plays a crucial role in our natural environment. These microscopic particles travel between plants, usually from early spring to late summer, facilitating their reproduction. Some pollen is spread by insects, while others are carried by the wind. Unfortunately, they trigger allergies in sensitive individuals, which are now becoming more severe. Scientists believe that rising global temperatures are lengthening the pollen season, resulting in more pollen in the air.
Climate change will extend the pollen season by additional months
"We know that climate change is leading to greater amounts of pollen in the atmosphere. It's changing the seasonality of the pollen. It's changing the types of pollen that we're exposed to," says BBC's Paul Beggs, a scientist at Macquarie University in Sydney. This phenomenon is particularly noticeable in Europe, the United States, and Australia.
Researchers predict that pollen levels will exceed the historical average in 39 U.S. states this season. This means that people suffering from allergies may experience symptoms for a longer period. "The winter warms, the springs are starting earlier, and the falls are being delayed, and so the time that you spend outdoors in contact with allergic pollen is definitely going up," says BBC's Lewis Ziska from Columbia University.
Scientists believe that without immediate reductions in greenhouse gas emissions, the situation will likely worsen. Authors of scientific studies published in "Nature" (Y. Zhang, A. Steiner) estimate that by the year 2100, pollen seasons will begin up to 40 days earlier and end up to 15 days later than they do now—potentially resulting in an additional two months of symptoms for hay fever sufferers annually.
This is how carbon dioxide affects plants
This issue is partly due to rising levels of carbon dioxide (CO2) in the atmosphere, resulting from human activities. Many of the plants most troublesome for hay fever sufferers thrive on CO2.
The spread of invasive species to new regions also triggers allergic reactions in new populations. In parts of the world, including the U.S. and Europe, one of the main culprits is ragweed (Ambrosia L), part of the aster family—a group of widespread flowering plants often considered weeds. Various species of ragweed exist worldwide, and they can produce enormous amounts of pollen. A single plant can emit a billion grains of pollen. Ragweed grows in gardens and agricultural fields, as well as in urban areas.
Ziska, author of the book "Greenhouse Planet" from 2022, conducted experiments with ragweed. "Every time we cranked up the carbon dioxide, the ragweed plants responded. They grew more. They produced more pollen," he told the BBC. He also added that there is "some evidence that they were producing a more allergenic form of the pollen, one that could induce your immune system to respond even to a greater extent than had been in the past."
Climate change significantly impacts human health, and without coordinated efforts, the situation may worsen. "We now have research showing that it really affects human health," asserts a scientist from Macquarie University in Sydney.
