Allergy season is getting longer. Blame climate change
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Most major U.S. cities are suffering from longer allergy seasons amid human-caused climate change, a new analysis finds.
Why it matters: Millions of Americans endure runny noses, itchy throats, and worse health effects each spring allergy season.
Driving the news: The freeze-free growing season lengthened between 1970 and 2024 in nearly 90% of the 198 cities analyzed by Climate Central, a research and communications group.
- Among those cities, the freeze-free season lengthened by 20 days on average.
How it works: Climate Central uses the freeze-free period — the number of consecutive days with minimum temperatures above 32°F — as a proxy for allergy season.
- Above-freezing temperatures allow for better plant growth, and thus the release of more sneeze-inducing pollen.
Zoom in: Reno, Nevada (96 more consecutive freeze-free days from 1970 to 2024); Myrtle Beach, South Carolina (52) and Toledo, Ohio (45) have had some of the biggest increases among the cities analyzed.
- Conversely, the number of consecutive freeze-free days decreased in places like Waco, Texas (-14); Tulsa, Oklahoma (-14), and Denver, Colorado (-8).
Between the lines: "Climate change makes pollen seasons not only longer, but also more intense due to heat-trapping pollution," per Climate Central's report.
- "Higher levels of planet-warming CO2 in the air can boost pollen production in plants, particularly in grasses and ragweed."
Threat level: Nationwide pollen production stands to dramatically increase alongside high CO2 pollution, per a 2022 study highlighted in the report.
The bottom line: Pass the allergy spray, would ya?
