North American ragweed to bring autumn allergy misery to Europe

2019-03-04 08:12:00

By Andy Coghlan (Image: Inra-Dijon) European allergy sufferers resigned to the perennial springtime blitz on their noses may need to keep their tissues handy later in the year too. An invasive plant from North America that releases copious amounts of allergenic pollen in the autumn looks set to massively expand its range in Europe. What will drive the spread of common ragweed (Ambrosia artemisiifolia) is a combination of climate change and accidental dispersal of its seeds. In Europe, ragweed is most commonly reported in areas of northern Italy and southern France. But computer modelling predicts that by 2050 it will be found in parts of eastern and northern Europe, including Germany, Ukraine, Romania, the UK and the rest of France. “Ragweed will continue to invade Europe, and the airborne pollen concentrations will by 2050 increase by a factor of 4 on average,” warns Lynda Hamaoui-Laguel of the Laboratory of Climate Science and the Environment in Gif-sur-Yvette, France, whose team produced the computer simulations. “Seed dispersal will increase mainly through transport – mainly along roads by agricultural equipment – and also via waterways and by contaminating consignments of commercial seeds,” she says. Meanwhile, rising temperatures will also make areas of eastern and northern Europe ripe for a ragweed invasion. Longer summers will mean more ragweed plants will complete their life cycle and produce mature seeds, and extra carbon dioxide in the atmosphere will nourish the plants, helping them produce even more pollen. Ragweed is abundant in North America, where a quarter of the population are sensitised to it. It is the third largest allergy trigger, fractionally behind dust mites and rye grass pollen. As few as 20 ragweed pollen grains per cubic metre of air can provoke an allergic response, and actual concentrations can be 10 times that. “It’s most likely to affect those who already suffer from hay fever and react to pollen from our native trees, particularly birch, and to grass and weed pollens,” says Maureen Jenkins, clinical director of the charity, Allergy UK. “This would add to the severity of their symptoms and will extend the length of time they suffer the debilitating effects of this disease.” Hamaoui-Laguel says the only way to prevent ragweed’s advance through Europe is through a coordinated program of uprooting and destroying as many of the plants as possible before they flower. Journal reference: Nature Climate Change, DOI: 10.1038/nclimate2652 Ragweed is more commonly seen in Europe than an earlier version of this article stated. More on these topics: