Pollen allergies and climate change: it’s only going to get worse!

Seasonal pollen allergies are intensifying – scientists warn. In addition to global warming itself, severe storms also pose a serious threat, as they break down airborne allergens, triggering violent respiratory reactions. The forecast is especially worrying for people with asthma.

Thunderstorm asthma: a pollen catastrophe

In November 2016, an unusual storm broke out over Melbourne, Australia. Billions of pollen particles were sucked into forming clouds and then violently dispersed by rain and lightning, saturating the air with allergens and causing a real disaster. Thousands of patients flooded hospitals after experiencing severe asthma attacks triggered by pollen allergies, making it impossible for them to breathe. Ten people couldn’t be saved.

Scientists dubbed the extraordinary event “thunderstorm asthma,” and in the last two decades, similar cases have been observed not only in Australia but also in the UK, the United States, Kuwait, Saudi Arabia, and Italy. The mechanism is similar in each case: warm updrafts lift plant and fungal spores high into the clouds, where moisture and lightning cause them to split into particles smaller than 3 µm. These are then brought down to the ground with rain and cool air.

The small size of the allergens allows them to penetrate deep into the respiratory system, bypassing the body’s natural defences. Thunderstorm asthma has even been observed in individuals who previously showed no signs of allergies.

Pollen allergies are getting worse

The increasing intensity of storms is only one consequence of climate change. Rising temperatures alone are extending the pollen season in many regions of the world, making life significantly harder for allergy sufferers. Some species are now reported to release pollen twice a year due to the warmer weather.

U.S. forecasts for 2025 predict that in most states, pollen levels will reach historic highs. Across the Northern Hemisphere, higher temperatures are increasing the amount of allergens in the atmosphere, making pollen allergies more common. In Europe and the United States, ragweed (Ambrosia artemisiifolia) poses a particular problem, with a single plant producing up to a billion pollen grains. As an invasive species, it’s spreading to new areas, causing severe allergic reactions in newly exposed populations.

The intensity of pollen production by trees, grasses, and herbs also appears to rise in the presence of elevated carbon dioxide levels. American scientists have shown that increased CO₂ can boost pollen production per flower by as much as 50%. Korean research on oak trees found that raising CO₂ levels from 400 ppm to 772 ppm resulted in a thirteenfold increase in allergen emission.

Bleak prospects for allergy sufferers

Delays in reducing greenhouse gas emissions do not bode well for people with asthma. A 2022 study published in Nature Communications predicts that climate change will extend the pollen season in the United States by up to 55 days. In the past two decades alone, airborne pollen levels have increased by 46%, with no sign of this trend slowing. In Europe, a fourfold increase in ragweed pollen concentrations by 2050 was forecasted a decade ago—due in part to the spread of invasive species, and in two-thirds, to climate change.

Will pollen allergies become an epidemic, and will thunderstorm asthma become more common? Analysts suggest that the risks can be mitigated by responsible urban planning of green spaces. It’s also crucial to develop real-time pollen monitoring systems, which are far more important for allergy sufferers than traditional weather forecasts.