Longer Allergy Seasons Linked to Climate Change in U.S. Cities
A recent analysis highlights the impact of climate change on allergy seasons in the U.S., with longer freeze-free growing periods observed in several cities. According to Climate Crisis 247, the freeze-free season, defined as consecutive days with minimum temperatures above 32°F, has significantly increased in many locations since the 1970s. This change is tied to warming temperatures and higher carbon dioxide levels, which encourage plants to produce more pollen. Reno, Nevada, experienced the largest percentage increase, with its freeze-free season growing by 69.6%, from 112 days in the 1970s to 190 days in recent years. Other cities, including Missoula, Montana, and Las Cruces, New Mexico, also saw notable increases. These extended growing seasons are a proxy for longer allergy seasons, particularly affecting regions with high ragweed pollen levels.