A number of scientists have warned that this could be one of the worst pollen seasons ever for parts of the country. They attribute this to a number of factors, including the high levels of carbon dioxide in the atmosphere which provide a fertilization effect on some plants and warmer temperatures and wet conditions in some regions, which extend the growing season and make the plants grow more vigorously. The Weather Channel published an article last week which described how this could become more common as changing climate and rising carbon dioxide levels make plants produce more pollen in the future.
EcoWatch also had an article last fall which explained how climate change could increase pollen levels (link).
Meanwhile, Yahoo News published an article yesterday which discussed how the earth is getting greener even with deforestation due to the warming temperatures, which allow areas formerly covered by snow and tundra to warm up and produce vegetation. Presumably this could lead to even more pollen production in the future as the area of vegetation expands.
