Thunderstorms Helping Bring Ozone Down to Earth

Ozone is a bit of a shape-shifting chemical. High in the stratosphere, ozone acts as an ultraviolet-blocking shield around Earth (which is why the ozone hole is such a problem).  At ground level, it’s a pollutant that can cause serious respiratory problems.  And if it finds its way into the troposphere — the lowest level of the atmosphere — ozone serves as a potent greenhouse gas that warms the planet.

It ends up in the troposphere through a variety of processes including human pollution. It also finds its way there by trickling down from the stratosphere.  In the past, scientists have attributed the trickle between the atmosphere’s different layers to large-scale patterns, such as shifts in the jet stream or air moving from the tropics toward the poles.

But for the first time, research has definitively shown that it’s not just these large-scale movements that lure ozone down from the stratosphere, it’s also smaller-scale events like thunderstorms.  

“The convective-scale events like thunderstorms are smaller.  They’re not explained well in global climate models but we know they’re important,” scientist Laura Pan, the lead author of the new research published in Geophysical Research Letters, said.

Pan’s findings could be important to climate modelers looking to get a better handle on just how greenhouse gases end up in the troposphere and where they go once they get there.

Some research has projected that severe storms — or at least the conditions favorable for their formation — could increase by 40 percent over the U.S. by 2100 during the height of severe storm season if our carbon dioxide emissions continue unabated.  The new research could be a warning about a potentially unexplored feedback loop that could further warm the planet, with more storms bringing more warming ozone to the lower levels of the atmosphere.

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