Source: Agricultural Research Service

Studies by a U.S. Department of Agriculture (USDA) scientist and cooperators have confirmed what many already suspected: In some parts of North America, ragweed season now lasts longer and ends later.

Ragweed pollen in some parts of the northern United States and Canada now lingers almost a month longer than it did in 1995, and these increases are correlated to seasonal warming shifts linked to climate change dynamics in the higher latitudes, according to a study published Monday in the Proceedings of the National Academy of Sciences. 

Original news release