Pollen season is getting longer and more intense thanks to Climate Change. The paper analyzed changing pollen counts across 60 North American stations from 1990 to 2018. The researchers also looked at several climate models to see what role climate change played in these increases. They found that human-caused climate change was the main driver of longer, more intense pollen seasons over the last three decades. Advertisement While pollen season extends into the fall, the study found the biggest increases in pollen concentrations happen in the spring.