Science Source

Recent warming by latitude associated with increased length of ragweed pollen season in central North America

States that a fundamental aspect of climate change is the potential shifts in flowering phenology and pollen initiation associated with milder winters and warmer seasonal air temperature
States that earlier floral anthesis has been suggested, in turn, to have a role in human disease by increasing time of exposure to pollen that causes allergic rhinitis and related asthma
Reports that duration of the ragweed (Ambrosia spp.) pollen season has been increasing in recent decades as a function of latitude in North America
Finds that latitudinal effects on increasing season length were associated primarily with a delay in first frost of the fall season and lengthening of the frost free period
Overall, these data indicate a significant increase in the length of the ragweed pollen season by as much as 13–27 d at latitudes above ~44°N since 1995
Concludes that this consistent with recent Intergovernmental Panel on Climate Change projections regarding enhanced warming as a function of latitude
Concludes that if similar warming trends accompany long-term climate change, greater exposure times to seasonal allergens may occur with subsequent effects on public health