A new study released in Europe shows that most seasonal allergies such as hay fever are likely heightened in recent years due to the ongoing increase in global CO2 levels. The study took place in thirteen different nations and the analysis targeted over 20 different species of plants and trees. The findings showed that many showed pollen production spikes that are essentially in keeping with the rise in CO2 emissions. One possible method to help overcome this according to the report is having city planners better evaluate which trees are planted in future. That solution of course doesn’t address the larger issues of reducing carbon emissions globally.

Interestingly the obvious assumption that temperature dictates pollen levels, the study did not demonstrate that to be the case as there was more correlation between ongoing increases related to emissions irrespective of the particular year being warmer or cooler. Some interesting observations from the team working on the study:

“We thought the increase in the amount of pollen could be related to land use changes, but we don’t observe this. We tried to link it to temperature, but that’s not possible. So the only effect that’s left would be a CO2 effect; and we know from experiments in the real world and in climate chambers that CO2 does promote the amount of pollen [that trees produce]. The season of suffering for people with hay fever is getting more serious”

The increase in pollen across all of the planets and trees studied was not universal however with some species having declined but pivotally the types that cause allergic reactions were more likely to have increased. The finding that will probably cause the greatest reaction is that pollen counts were more likely to increase along with CO2 levels within urban areas but not outside. The explanation given is that ‘urban’ areas shorten the lifetime of ozone molecules. The main impact of the changes from the trees and plants isn’t limited to pollen levels but the lengths of the pollen seasons which are uniformly growing longer in many cities, a problem that is expected to continue. The next stage will most likely look to determine how and why the increased CO2 levels are causing the biology of the plants and trees to react in the way that they are.