The Journal of Allergy and Clinical Immunology had a recent article on global warming and the allergy epidemic. Allergic diseases have reached epidemic proportions globally affecting 30% of the people on earth. Just 20 years ago statistics in the US showed allergy affecting roughly 15 to 18% of Americans. Despite new therapies allergic conditions are increasing in spectrum, frequency and severity.
Since 1970 average temperatures have increased by 2 degrees Fahrenheit and green house gases have increased dramatically (primarily carbon dioxide and methane). Thus, climate change has invoked allergic disease by a variety of mechanisms. The changes in rainfall patterns, storms and winds affect pollination including the length and severity of pollen seasons. Plants produce more pollen with higher levels of carbon dioxide. Pollens are not only allergenic but carry lipid mediators that are proinflammatory.
Flooding increases ambient mold levels. More severe thunderstorms fractionate (split) pollens and make them more allergenic. Wildfires and dust storms have both local and remote impacts.