A runny nose, itching eyes, worsening asthma symptoms — the effects of hay fever are certainly nothing to sneeze at, experts warn, highlighting an “explosion” of allergies as climate change prolongs and intensifies pollen seasons.
The UN’s World Meteorological Organisation (WMO) has identified that a shifting climate has already begun to alter the production and distribution patterns of pollen and spores. Numerous studies have consistently shown that as winter frost thaws earlier and spring weather becomes warmer, plants and trees flower prematurely, thereby extending the overall pollen season. Furthermore, air pollution can heighten individuals’ sensitivity to allergens, while invasive species are expanding into new regions, triggering fresh waves of allergic reactions.
In recent decades, an increasing number of people, particularly within industrialized nations, have reported developing allergy symptoms. Approximately a quarter of adults in Europe suffer from airborne allergies, including severe asthma, with this proportion rising to between 30% and 40% among children. The World Health Organisation projects that this figure is expected to reach half of all Europeans by 2050.
“We’re in crisis because allergies are exploding,” stated Severine Fernandez, president of the French Allergists’ Union. She noted that while an allergic person previously might only endure what is commonly known as hay fever, albeit sometimes for years, “now that person can become asthmatic after one or two years.”
Irritant Pollen: Climate Change’s Multifaceted Impact
According to a 2023 report by the WMO, climate change impacts allergy patients in multiple ways. Elevated levels of carbon dioxide, a primary heat-trapping gas produced by burning fossil fuels, stimulate plant growth, which in turn leads to increased pollen production. Air pollution not only irritates the airways of exposed individuals but also induces stress in plants, causing them to produce more “allergenic and irritant pollen.”
Nicolas Visez, an aerobiologist at the University of Lille, explained that each plant species reacts distinctly to various factors such as water availability, temperature, and CO2 concentrations. For instance, birch trees may wither as summers become hotter and drier, while the increased heat promotes the proliferation of ragweed, a highly allergenic invasive plant. “There’s no doubt that climate change is having an effect,” Visez affirmed.
A study published in 2017 projected that ragweed allergies would more than double in Europe by 2041-2060 as a direct consequence of climate change, potentially raising the number of affected individuals from 33 million to 77 million. The authors suggested that both higher pollen concentrations and longer pollen seasons could lead to more severe symptoms.
Global Initiatives to Combat Allergies
To address this growing crisis, a Europe-wide “AutoPollen” program is under development, aiming to provide real-time data on the distribution of pollen and fungal spores. In Switzerland, a collaboration with MeteoSwiss enables patients and doctors to align personal allergy profiles with maps illustrating specific allergen concentrations across the country.
In certain parts of France, authorities have established “pollinariums”—gardens specifically cultivated with the main local allergen species. These initiatives offer information on the very first release of pollen into the air, allowing individuals to begin taking antihistamines and other protective measures in a timely manner. “Hazelnuts have started to bloom as early as mid-December, which wasn’t the case before,” observed Salome Pasquet, a botanist with the association behind these pollen gardens. “That’s really because we’ve had very mild winters, so flowering has come earlier,” she explained.
Some countries are adopting a more interventionist approach by tackling the pollen at its source. In Japan, the government announced a plan in 2023 to combat allergies caused by the archipelago’s numerous cedar trees. This plan includes felling cedars and replacing them with species that produce less pollen. European countries are also demonstrating increased mindfulness regarding environmental species, both native ones that have been planted and invasive newcomers like ragweed. Preference is being given to species with lower allergenic potential, such as maple or various fruit trees.
“The idea is not to stop planting allergenic species,” Pasquet clarified, but rather to prioritize creating biodiversity and avoiding “places where there are rows of birch trees, as was the case a few years ago.”
Simon Barthelemy, an architect residing near Paris, experienced the onset of his allergy symptoms due to birch trees in a client’s garden. “I had a major eye allergy, and it’s been a recurring problem every year since,” he shared. “I’m on antihistamines, but if I don’t take them I get itchy eyes, I’m very tired, I cough… I can’t sleep at night.”
