Pollen levels on the rise thanks to climate change, scientists say

Roxanne Palmer in the International Business Times: An unseasonably warm winter made 2012 one of the worst years for people with allergies, but scientists say it's just the start of an upward trend. Thanks to climate change, pollen counts are only going to climb higher, more than doubling by the year 2040.

Nearly 8 percent of people over the age of 18 in the U.S. have hay fever, or allergic rhinitis, which is primarily triggered by plant pollen. People with pollen allergies have immune systems that overreact to the presence of plant pollens and flood the body with inflammatory molecules, including histamines.

More pollen and longer pollen seasons will mean many more sniffly and itchy days for allergy sufferers. At a meeting for the American College of Allergy, Asthma and Immunology, allergist Leonard Bielory presented results from a study modeling climate change's predicted effect on pollen counts that is in progress at Rutgers University.

"Climate changes will increase pollen production considerably in the near future in different parts of the country," Bielory said in a statement Friday. "Economic growth, global environment sustainability, temperature and human-induced changes, such as increased levels of carbon dioxide, are all responsible for the influx that will continue to be seen."...

Frozen balls of pollen, shot by Lamiot, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported

USDA study confirms links between longer ragweed season and climate change

Ann Perry in the USDA News: Studies by a U.S. Department of Agriculture (USDA) scientist and cooperators have confirmed what many pollen-sensitive people already suspected: In some parts of North America, ragweed season now lasts longer and ends later. Ragweed pollen in some parts of the northern United States and Canada now lingers almost a month longer than it did in 1995, and these increases are correlated to seasonal warming shifts linked to climate change dynamics in the higher latitudes, according to a study published Monday in the Proceedings of the National Academy of Sciences.

"One of the biggest challenges in studying climate change is finding out how the plant kingdom is adapting to increases in air temperature and other meteorological phenomena," said Agricultural Research Service (ARS) Administrator Edward B. Knipling. "Studies like this also show us that these ecological shifts don't stop at crop production. They can also have a significant impact on public health."

…Lewis Ziska, a plant physiologist with the ARS Crop Systems and Global Change Research Unit in Beltsville, Md., led a scientific team that identified 10 locations that had at least 15 years of data, from 1995 to 2009, on local ragweed pollen counts. These locations were along a north-south transect from Austin, Texas, to Saskatoon, Canada. The researchers compared the pollen data at each site to other site data, including latitude, the number of frost-free days, and delays in the onset of the first fall frost.

The researchers found that from 1995 to 2009, the number of frost-free days at higher-latitude study sites had increased, and so had the length of the ragweed pollen season. During that period, the pollen season lasted from 13 to 27 days longer than in 1995. They also found that a longer ragweed pollen season was strongly correlated with a delay in the onset of the first fall frost….

Common ragweed shot by Sue Sweeney, Wikimedia Commons, under the Creative CommonsAttribution-Share Alike 3.0 Unported license

Rising CO2 raises allergen levels

Medical News Today: Bad news for 35 million allergy sufferers - ragweed, fungal spores and poison ivy are thriving due to rising carbon dioxide levels. At the annual scientific meeting of the American College of Allergy, Asthma and Immunology (ACAAI) in Phoenix, Nov. 11-16, allergists and scientists discussed the effects of rising CO2 levels and a changing climate on plant biology and public health.

"Plant-based respiratory allergies are on the rise and increased levels of ragweed pollen are in the air," said ACAAI symposium presenter Lewis Ziska, PhD, a plant physiologist with the USDA Agricultural Research Service. "Climate change is affecting plants and human health, especially allergy sufferers." Additionally, leaves fed by heightened levels of carbon dioxide enable fungi to reproduce more rapidly and spread more allergenic spores, leading to higher rates of allergies and asthma.

Climate change also affects allergen levels in homes, schools and offices. Not only are people allergic to outdoor allergies going to experience more symptoms, so are people with indoor allergies. "Climate change causes indoor humidity levels to increase, which may contribute to the proliferation of dust mite and mold - allergy triggers for many people," said allergist and ACAAI member Wanda Phipatanakul, MD. "Furthermore, people stay indoors with higher humidity levels and allergic individuals then have more exposure to indoor allergens."…