Climate Change Lengthens and Intensifies U.S. Allergy Seasons

About one in four U.S. adults and one in five children experience seasonal allergies, according to recent survey data. For these individuals, spring typically brings symptoms such as sneezing, itchy eyes, and asthma flare‑ups. Climate scientists have observed that increasing average temperatures and elevated carbon dioxide concentrations stimulate plant growth and pollen production.

The USA National Phenology Network reports that spring bloom arrived early across much of the country this year, a shift consistent with multi‑decadal observational trends. Dr. Neelima Tummala, an ear, nose, and throat specialist at NYU Langone Health, notes that her patients describe their allergy symptoms as the worst they have ever experienced. While no randomized controlled trial can ethically test climate exposure on humans, longitudinal cohort studies tracking pollen counts over the past 30 years show a clear correlation between warmer seasons and higher airborne allergen levels.

For allergy sufferers, an earlier and longer pollen season means medication may need to start sooner and possibly be taken for a longer duration. Public health officials suggest monitoring local pollen forecasts and adjusting outdoor activities on high‑count days. Continued warming could further extend the season into late summer, increasing the burden on healthcare systems.