Climate change is intensifying allergy seasons worldwide, with longer pollen seasons and more severe episodes such as thunderstorm asthma. Rising temperatures are extending allergy seasons, with major health impacts in the US, Europe, and Australia. The increasing pollen levels, along with extreme weather events, are making life difficult for millions of allergy sufferers. Environmental health experts warn that these trends will worsen without urgent action on climate change.

Climate Change Lengthens Pollen Seasons

The consequences of climate change on pollen seasons are becoming more evident. Global warming is not only extending the duration of pollen seasons but also making them more intense. Higher temperatures lead to an increase in pollen production by certain plants, such as ragweed, trees, and grasses, which are major culprits behind hay fever and asthma.

In the US, for example, 39 states are forecasted to experience above-average pollen levels in 2025. Scientists predict that future allergy seasons will continue to grow in intensity. Ragweed, a major allergen, thrives under higher levels of carbon dioxide, and this is contributing to the worsening of allergy symptoms.

Thunderstorm Asthma: A New and Deadly Risk

Thunderstorm asthma is a phenomenon that exemplifies how climate change is aggravating allergies. During thunderstorms, powerful winds carry large amounts of pollen, which storms then break down into smaller, more allergenic particles. These particles can trigger severe allergic reactions, even in people who have never had asthma before.

One of the most devastating instances of thunderstorm asthma occurred on November 21, 2016, in Melbourne, Australia. On that day, a severe thunderstorm triggered a sudden increase in asthma-related cases, overwhelming emergency services and hospitals. Ten people died, including a law student who collapsed in her yard. Environmental health scientist Paul Beggs recalls the event as “unprecedented and devastating.”

Since then, Melbourne has experienced several more thunderstorm asthma events, and similar outbreaks have been reported in other cities such as Birmingham, UK, and Atlanta, US. The increasing frequency of these incidents highlights the growing risk posed by climate-induced extreme weather.

The Growing Pollen Problem

In addition to thunderstorm asthma, rising temperatures are leading to longer exposure to pollen. For example, ragweed plants can release up to one billion pollen grains, and the warmer weather helps these plants thrive in more regions. A single ragweed plant, once native to North America, is now spreading across Europe, Asia, and South America, causing allergic reactions in millions of people.

By 2050, pollen concentrations from ragweed could quadruple in Europe, affecting even areas with currently low pollen levels, like the UK and Germany. In fact, up to 60% of Hungarians, 20% of Danes, and 15% of Dutch citizens already suffer from ragweed allergies. As climate change accelerates, new populations will likely develop sensitivities, and people will experience more severe and prolonged allergy seasons.

Scientific Research Links Climate Change to Allergies

Research is uncovering the direct link between climate change and the increase in pollen production. Studies show that plants like ragweed are producing more pollen under elevated CO2 levels. Dr. Lewis Ziska, a prominent researcher in plant biology, has observed that ragweed plants grow larger and produce more allergenic pollen when exposed to higher carbon dioxide concentrations.

Climate models predict that by the end of the century, pollen seasons could begin 40 days earlier and end 15 days later, resulting in two extra months of allergy symptoms. In regions like the Northern Hemisphere, which includes parts of the US, Europe, and Asia, these extended allergy seasons are expected to impact millions of people.

Rising Risks and the Need for Global Action

The worsening pollen seasons are not confined to a specific region but are becoming a global issue. From North America to Europe and beyond, more people are experiencing longer and more intense allergy seasons. Invasive species like ragweed are now thriving in regions far beyond their native habitats, contributing to a broader geographic spread of allergies.

Experts such as Elaine Fuertes from Imperial College London emphasize that reducing emissions could help alleviate some of the more severe effects of climate change on allergy seasons. Some cities have already taken action by removing ragweed plants, while Switzerland has even banned ragweed imports and formed volunteer teams to eradicate the plant.

Solutions to Combat the Allergy Epidemic

Addressing this growing issue requires both global and local actions. One of the most effective solutions involves reducing greenhouse gas emissions, which directly contribute to the extended pollen seasons. Cities like Berlin are already tackling the problem by organizing ragweed removal teams. In New York City, efforts to remove ragweed in the past led to a 50% reduction in pollen levels.

Urban planning can also play a role in mitigating allergy symptoms. By creating more green spaces and carefully selecting plants that produce fewer allergens, cities can help reduce the exposure of residents to pollen. However, experts warn against “botanical sexism,” where male trees, which produce more pollen, are chosen over female trees, exacerbating allergy problems.

A Growing Threat to Public Health

Without global action to mitigate climate change, the allergy epidemic is expected to worsen. Scientists are calling for more data on airborne allergens, as current monitoring systems do not accurately track allergens in real-time. The evidence is clear: climate change is affecting human health in many ways, and allergies are becoming an increasingly severe issue for millions of people worldwide