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    You’re not imagining it: The pollen increase is real, and it’s linked to climate change

    A runner jogged past a car covered in pollen in Charlestown.
    Jessica Rinaldi/Globe Staff
    A runner jogged past a car with in pollen on it in Charlestown.

    Did it seem like your allergies kicked in a little bit earlier this year and have been worse than ever? Has the sneezing become more than just annoying? You might want to partially blame the increase in carbon dioxide.

    While the precise future climate of individual areas of the globe can be debated, there is emerging data showing a world with more carbon dioxide means more pollen, and more pollen is leading to more health issues, today. This is real.

    Now, I realize many times you turn on the television or read an article about almost any event it’s being linked to climate change. It can be hard to grasp how a changing climate is or isn’t affecting your daily life. While long-range computer projections forecast rising seas and more frequent and more intense heat waves, your day-to-day living probably hasn’t changed much, yet. After all, storms have occurred for millennia and will continue to plague the globe for centuries to come. Their impact in a future warmer world is uncertain, but the increase in pollen is here now.

    CO2 Is Plant Food

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    If you remember your basic biology from elementary school you’ll recall that carbon dioxide is what plants take in, while they give off oxygen. If you increase the carbon dioxide, you essentially give plants more food and many of these are responding in kind. A recent article in The Lancet Planetary Health journal looked at how the increase in CO2 is leading to more pollen.

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    This study looked at data over several different continents and found around 70 percent of the areas evaluated had significant increase in their pollen season. We can hone in here on several different US cities and notice that the pollen season is rapidly expanding. In the spring the trees are leafing out earlier and in the fall the ragweed is lasting longer.

    The US Global Change Research Program Photo credit.
    Lewis Ziska, USDA
    The US Global Change Research Program Photo credit.

    It makes sense that areas to the north are seeing a more dramatic increase in pollen production. In the deep south they’re already frost-free most of the year, so a day or two longer won’t make nearly as much difference as it will up here, when we go from having no pollen all winter to a sudden increase.

    The number of frost free days is growing. This is giving more time for pollen production.
    NOAA
    The number of frost free days is growing. This is giving more time for pollen production.

    The projections moving forward are for even more pollen production. By the time we get to the middle of the 21st century, carbon dioxide is expected to be near 600 parts per million, and this will rapidly increase the amount of pollen being produced by all plants.

    As CO2 increases so too will the number of pollen grains in the air.
    Climate Central
    As CO2 increases so too will the number of pollen grains in the air.

    The bad news is there’s not really anything you can do about this.

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    In your lifetime the pollen is only going to increase. How bad this problem potentially becomes 100 years from now remains to be seen. At least you now know that if you think the pollen has been getting worse, it’s not your imagination.

    Follow Dave Epstein on Twitter @growingwisdom.