Climate change and future pollen allergy in Europe

Background: Globally pollen allergy is a major public health problem, but a fundamental unknown is the likely impact of climate change. To our knowledge, this is the first study to quantify the consequences of climate change upon pollen allergy in humans. Objectives: To produce quantitative estimates of the potential impact of climate change upon pollen allergy in humans, focusing upon common ragweed (Ambrosia artemisiifolia) in Europe. Methods: A process-based model estimated the change in ragweed’s range under climate change. A second model simulated current and future ragweed pollen levels. These were translated into health burdens using a dose-response curve generated from a systematic review and current and future population data. Models considered two different suites of regional climate/pollen models, two greenhouse gas emissions scenarios (RCP4.5 and 8.5), and three different plant invasion scenarios. Results: Our primary estimates indicate that sensitization to ragweed will more than double in Europe, from 33 to 77 million people, by 2041-2060. According to our projections, while sensitization will increase in countries with an existing ragweed problem (e.g. Hungary, the Balkans), the greatest proportional increases will occur where sensitization is uncommon (e.g. Germany, Poland, France). Higher pollen concentrations and a longer pollen season may also increase the severity of symptoms. Our model projections are driven predominantly by changes in climate (66%), but also are influenced by current trends in the spread of this invasive plant species. Assumptions about the rate at which ragweed spreads throughout Europe have a large influence upon the results. Conclusions: Our quantitative estimates indicate that ragweed pollen allergy will become a common health problem across Europe, expanding into areas where it is currently uncommon. Control of ragweed spread may be an important adaptation strategy in response to climate change