Climate change lengthening pollen season in U.S., study shows

Researchers have identified a strong connection between climate change and longer pollen seasons in North America. The study, published in the Proceedings of the National Academy of Sciences found that the combination of warming air and increased levels of carbon dioxide in the atmosphere has led to North American pollen seasons since 1990 to start about 20 days earlier, on average, with 21% more pollen. According to the authors, climate change was behind about one-half of the trend in the pollen season and 8% of the higher pollen count. The pattern of higher pollen counts is also increasing, they said. The effects were most visible in Texas, the Midwest, and the Southeast, the researchers said, with the greatest pollen increases coming from trees. For their study, the researchers examined data collected by 60 long-term pollen monitoring stations around the continental United States and compared the findings with a number of climate models to find correlations. The study concluded that “a clearly detectable and attributable fingerprint of human-caused climate on North American pollen loads provides a powerful example of how climate change is contributing to deleterious health impacts through worsening pollen seasons.”