Climate Change Could Cause Ragweed Allergies to Double

in Grass & Ragweed, News
Published: September 21, 2016
Screen Shot 2016-09-01 at 01.00.58Percentage of population with allergies to ragweed pollen at baseline and in the future. Credit: University of East Anglia

The number of people with allergic hay fever caused by ragweed pollen is expected to more than double in Europe over the next 35 years, with two-thirds of the increase caused by climate change, according to scientists at Britain’s University of East Anglia.

Currently, 33 million people in Europe are affected by ragweed pollen, a number that scientist projections indicate will grow to 77 million between 2041 and 2060.

Related symptoms are likely to be more severe and extend over a longer period in peak autumn periods when ragweed pollen proliferates, indicating that controlling the plant may be an important adaptation strategy in response to climate change, researchers said.

“Pollen allergy is a major public health problem globally, but it has not been known what sort of an impact climate change will have,” said Dr. Iain Lake, who led the study, which involved creating maps of projected ragweed pollen counts and combining them with population data and allergy levels to make predictions.

“Management of this invasive plant could reduce the amount of people affected to about 52 million, while a scenario which sees very rapid plant invasion would increase the amount of people affected to around 107 million,” he added.

Ragweed is expected to move increasingly northward, said researchers, who investigated the potential impacts of climate change on ragweed plant distribution, plant productivity, pollen production and dispersal, and the resulting impact on allergies in Europe.

Although more people will develop ragweed-related hay fever in countries with an existing ragweed problem, the greatest proportional increases are projected to occur in such countries as France, Germany and Poland where allergies related to the plant are relatively uncommon, the paper showed.

By 2041-2060, allergic sensitization to ragweed will be widespread across Europe, except in Scandinavia, the Baltic States, most of Spain, Portugal and Ireland.

The pollen of highly invasive ragweed is at its height in late summer, each plant producing about a billion grains of wind borne pollen a season making it especially harmful to public health.

The scientists generated monthly maps of estimated ragweed pollen counts over the pollen season to estimate changes in the severity of ragweed allergy symptom and their duration. They also created monthly maps of estimated ragweed pollen counts over the pollen season.

The models used by scientists considered two different regional climate-pollen models, two greenhouse gas emissions scenarios and three different plant invasion scenarios.

Climate change will affect the range of the plant, the timing and length of the pollen season and the release and atmospheric dispersion of pollen, scientists said. Elevated carbon dioxide emissions could increase plant productivity and pollen production.

Projections suggest that pollen will remain airborne in the mid-September to mid-October period across most of Europe, likely due to delayed frosts.

Pollen is a major risk factor for allergic diseases such as allergic asthma and rhinoconjunctivitis,which can cause nasal congestion, runny nose, sneezing and itching of the nose or eyes.

In 2014, the total cost of allergic diseases in the European Union was estimated to cost between €55 to €151 billion ($61 to $168 million).