Climate breakdown has extended the pollen season in the UK and mainland Europe by between one and two weeks since the 1990s, a study has found, adding itchy eyes and runny noses to the harm wrought by fossil fuel pollution.
The finding may be less dramatic than the floods and wildfires typically associated with a warming planet but represents a “huge” increase in the combined suffering of tens of millions of people, the researchers say.
“It’s one of those everyday indicators that show something is getting a little worse for a lot of people,” said Joacim Rocklöv, an environmental epidemiologist at the University of Heidelberg and co-director of the report. “The suffering of people from these changes can be very large.”
Warm weather and high concentrations of carbon dioxide let plants pump out more pollen, triggering allergic reactions in people with hay fever and leading to symptoms that range from mildly irritating to life-threatening.
The latest review of climate-health impacts in Europe, published in the Lancet medical journal, found the pollen seasons for birch, alder and olive trees began between one and two weeks earlier in 2015-24 than in 1991-2000.
Researchers found the seasonal severity of birch has increased 14-20% since 2024. Photograph: Shotshop GmbH/Alamy
Since the last version of the report in 2024, the researchers found the seasonal severity of birch and alder has increased by 15-20% in the south of the UK, northern France and Germany, and in eastern Europe.
Separate research has highlighted the danger of invasive species such as common ragweed. Its pollen is projected to become a common health problem across Europe as it expands into areas in which it is currently rare.
“Pollen allergies are a health risk of climate change,” said Katharina Bastl, a pollen researcher at the Medical University of Vienna, who was not involved in the research. “Global warming has already had an impact on pollination, [though] it is not that easy to assess and varies regionally.”
Compiled by 65 researchers from 46 academic and UN institutions, the Lancet Countdown tracks trends in climate change and health with 43 indicators. The latest iteration uses methodologies from peer-reviewed research to update established indicators with the latest data.
The researchers found heat deaths had increased over the study period by an average of 52 deaths per million people, while daily extreme heat warnings had quadrupled. Climate breakdown has helped infectious diseases to spread, with the potential for transmission of dengue thought to have more than tripled in recent decades.
In the past decade, 983 of 1,435 European regions experienced an increase in the length of “extreme to exceptional” summer drought compared with the four decades before, the report found.
The authors said the findings underscored the “urgent” need to adapt to a hotter planet. They highlighted measures such as greening cities and providing public health guidance that accounted for heat-related risks when people are physically active, as well as diverting subsidies from fossil fuels into clean energy.
Annual fossil fuel subsidies reached a new high in 2023 compared with 2010, the report found, rising to €444bn after governments tried to cushion the shock of soaring energy prices following Russia’s invasion of Ukraine.
Cathryn Tonne, an environmental epidemiologist at the Barcelona Institute for Global Health and co-director of the report, said the “window for action” was narrowing but that Europe still had an opportunity to protect lives.
“Redirecting investments from fossil fuels into clean energy, improving air quality, safeguarding vulnerable groups and preparing health systems for rising climate shocks will deliver immediate and long‑term health benefits.”
Not all of the trends the researchers examined have worsened. The death rate attributable to fine particle pollution from transport in the EU fell by 58% between 2000 and 2022. Deaths from pollution caused by electricity generation fell even faster, with an 84% drop.
“It’s a huge change,” said Rocklov. “It shows we can really benefit from the transition away from fossil fuels, and we can do it in a short time.”
