For millions across Europe, the tell-tale signs of spring—blossoming trees and warmer days—are now arriving with an unwelcome and intensified guest. Pollen seasons have stretched by one to two weeks since the 1990s, a significant extension driven directly by climate change, according to the latest data from a major health tracking report.
The finding, from the Lancet Countdown on health and climate change, means longer periods of itchy eyes and runny noses for allergy sufferers. While perhaps less immediately dramatic than wildfires or floods, researchers describe this as a “huge” increase in the combined suffering of tens of millions. “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 a co-director of the report.
How Climate Fuels the Pollen Surge
The mechanism behind this prolonged misery is a double assault from a warming world. Warmer weather triggers plants to start their pollination cycles earlier, while higher atmospheric concentrations of carbon dioxide—the primary greenhouse gas—act as a potent fertiliser. This allows plants to grow larger and produce more pollen, supercharging the seasonal severity for key allergenic trees.
The data, compiled by 65 researchers from 46 academic and UN institutions, shows pollen seasons for birch, alder, and olive trees now begin between one and two weeks earlier in the period 2015-2024 than they did from 1991-2000. Furthermore, since the last report in 2024, the seasonal severity of birch and alder pollen has increased by 15-20% in specific regions including southern UK, northern France and Germany, and eastern Europe.
Compounding the problem is the spread of invasive species. Separate research highlighted in the report points to the danger of common ragweed, whose highly allergenic pollen is projected to become a common health problem across Europe as the plant expands into areas where it is currently rare. Katharina Bastl, a pollen researcher at the Medical University of Vienna, confirmed that “pollen allergies are a health risk of climate change,” noting that while global warming has already impacted pollination, assessing the exact effect is complex and varies regionally.
A Broader Spectrum of Health Threats
The extended pollen season is just one of 43 indicators tracked by the Lancet Countdown, which paints a comprehensive picture of escalating climate-health impacts. Heat-related deaths have increased over the study period by an average of 52 deaths per million people, and daily extreme heat warnings have quadrupled.
The breakdown of climatic barriers is also aiding infectious diseases. The potential for the transmission of dengue fever, for instance, is thought to have more than tripled in Europe in recent decades. Meanwhile, drought is gripping the continent more fiercely; 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 prior.
The authors state these findings underscore an “urgent” need to adapt to a hotter planet. They advocate for measures such as greening cities to mitigate heat, and providing public health guidance that accounts for heat-related risks during physical activity.
The Fossil Fuel Subsidy Paradox
A critical barrier to addressing the root cause, however, is the continued flow of public money to the fossil fuel industry. The report found that annual fossil fuel subsidies reached a new high in 2023 compared with 2010, rising to €444bn. This surge followed government attempts to cushion consumers from soaring energy prices in the wake of Russia’s invasion of Ukraine.
Cathryn Tonne, an environmental epidemiologist at the Barcelona Institute for Global Health and the report’s other co-director, 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,” she said.
The report does, however, contain evidence that such a transition yields rapid results. It notes one clear success: 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, dropping by 84%. “It’s a huge change,” said Rocklöv. “It shows we can really benefit from the transition away from fossil fuels, and we can do it in a short time.”
