Provoked by the allergy forecast for today (medium-high) and Friday and Saturday (high), I did a little allergy season research. Despite growing up on a farm and working in actual hay fields, I didn’t used to get hay fever until a few years ago. I remember the exact moment when — with muggy eyes, streaming nose, and itchy throat — I realized this was what some people went through every year.

It’s true, I’ve gotten older, but things have also gotten worse. As MSNBC reports, allergy season is coming earlier and staying later, thanks to climate change. In some states, spring is arriving almost two weeks earlier than just twenty years ago.

But there’s a simpler explanation for rising allergies than even that. Scientists have long known that plants feed on carbon dioxide — now they are learning that pollen producers can binge on CO2. This March’s Annals of Allergy, Asthma, and Immunology contains a study showing that “ragweed grown in an atmosphere with double the current carbon dioxide levels produced 61 percent more pollen than normal.”

MSNBC also claims “the CO2 overload has also led to a kind of superpollen that’s more allergenic, so that just a teeny amount can get your nose running.” I haven’t found evidence of that, so I can’t tell you more. But, you know, the way things are going, sure.