According to a study by Harvard researchers, global warming could actually mean more pollen. The results of the study showed that ragweed could produce approximately 60% more pollen with double the current levels of CO2. If the global warming experts are right, we could have exactly those conditions sometime between 2050 and 2100.

It makes sense. Blog writer Thomas Ogren points out that if we add organic matter to the soil, we get increased plant growth; why wouldn’t they also produce more if they were getting more carbon dioxide out of the air? CO2 is a basic necessary component of the photosynthesis cycle. Plants use carbon dioxide to create sugars, and expire out the oxygen that we need to breathe.

It’s always been a good deal.

The ragweed study was done inside a controlled laboratory setting. So, you might think that we’re off the hook. Think again! A different team of researchers looked at what might happen if excess carbon dioxide was pumped into a pine forest. In that case, the pine trees tripled their production of both cones and seeds. Overall, the two studies suggest that carbon dioxide may increase a plant’s ability to reproduce.

This is not good news for those who suffer with seasonal allergies. More plant reproduction means more pollen – and higher pollen counts.

There’s an additional impact for urban dwellers. Most cities have been trying to clean up clutter. As a result, most of the female trees in urban areas have been removed because they produce more “mess”, like seedpods, fruit and other litter. We don’t like litter because it takes away from that manicured look and requires more work. Instead, most urban tree planting programs focus on the male trees. But the male trees produce pollen. Unfortunately, not only do the male trees produce pollen, but also there are no female trees (and seedpods) to take that pollen out of circulation. As a result, the pollen stays airborne, looking for a place to land. It’s likely landing point is your clothes, hair or respiratory tract.

So, if you want less pollen in your immediate environment, consider a female tree or two. You might have more raking to do, but you’ll have less pollen produced in your yard.