Allergy Attacks: Could Increase with Climate Change as Ragweed Pollen Spreads

It's allergy season, and as if everyone wasn't sneezing and wheezing enough, now new research says that allergy attacks could increase with climate change as the notorious ragweed pollen spreads.

Ragweed, or Ambrosia artemisiifolia, is native to North America but has been dispersing rapidly across warmer parts of Europe since the 1960s. Levels of this invasive weed are likely to quadruple for much of Europe because warmer temperatures will allow the plants to gain foothold, and carbon dioxide (CO2) will make them grow more. At least, that's according to new findings published in the journal Nature Climate Change.

Ragweed is capable of generating up to a billion grains per season. Its pollen can travel hundreds of miles and is resilient enough to survive a mild winter.

What's more, the plant's pollen not only induces severe allergic reactions but also extends the hay fever season from summer to autumn. Ragweed is a far more potent allergy trigger compared to grass, and experts fear it could pose a serious public health problem if it becomes established in Europe, including parts of France, the United Kingdom and Germany. And at this rate, that's exactly what we'll see by the year 2050, researchers say.

"Climate change and ragweed seed dispersal in current and future suitable areas will increase airborne pollen concentrations, which may consequently heighten the incidence and prevalence of ragweed allergy," they wrote.

Led by Dr. Lynda Hamaoui-Laguel from the Laboratory of the Sciences of Climate and the Environment in Gif-sur-Yvette, France, the team used computer simulations to forecast ragweed concentrations, taking into account different scenarios of CO2 pollution for the next 35 years. What they found was that if CO2 emissions don't drastically drop, by 2050 airborne ragweed pollen concentrations will be about four times higher than they are now. And depending on the speed of dispersal, pollen levels in some locations could rise as much as 12 times.

"Once established, ragweed is difficult to eradicate because of its long-lived seed, its capacity to re-sprout after cutting and its propensity to evolve resistance to herbicides," the scientists said.

"Our results indicate that controlling the current European ragweed invasion will become more difficult in the future as the environment will be more favorable for ragweed growth and spread, highlighting the need for the development of effective and regionally co-ordinated eradication programs."

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