Researchers from Europe, led by the University of East Anglia (UEA), estimated that across the continent the number of people who suffer an allergy to pollen will rise from 33 million to 77 million by 2060.
Climate change will be responsible for two-thirds of this increase, they said.
The study, published in the journal Environmental Health Perspectives, examined the potential impact of climate change on ragweed plant distribution, plant productivity, pollen production and dispersal, and the resulting allergy impacts across Europe.
People who are allergic to ragweed pollen are more likely to experience more severe symptoms through greater ragweed pollen concentrations and a longer pollen season lasting into September and October across much of Europe, the researchers said.
They said around 66% of the projected changes are related to climate change, but are also as a consequence of the natural dispersal of the plant species across Europe.
Lead researcher Dr Iain Lake, from UEA’s School of Environmental Sciences, said: “Our research shows that ragweed pollen allergy will become a common problem across Europe, expanding into areas where it is currently uncommon.
"The problem is likely to increase in countries with an existing ragweed problem, such as in Hungary and the Balkans, but the greatest proportional increases will happen in countries [such as] Germany, Poland, and France.”
He said management of the plant could reduce the number of sufferers to around 52 million.