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As the climate gets warmer, some mammals are getting smaller

Mar 23, 2017

Here’s one way to react to a warming planet: get smaller.

We know mammals literally shrank, during a massive global warming event 56 million years ago. Imagine an early horse ancestor the size of a cat.

Now back then, the earth was 46 degrees hotter on average than it is right now.

So researchers wanted to know: do mammals still experience shrinking - a.k.a. dwarfing - during other, less intense periods of warming?

Abigail D'Ambrosia is a researcher at the University of New Hampshire, and she did a study with scientists at the University of Michigan to answer that question.

“And we found that, yup! There’s definitely dwarfing in a couple of the mammals we found,” she says.

She says nobody's sure why generations of mammals gradually shrank during those periods of global warming in the past.

Maybe because it’s easier to cool yourself off if you’re smaller. Or maybe global warming killed off so many plants, animals didn’t get enough food.

D’Ambrosia thinks it’s some combination of the two, and she says we’re already starting to see mammals shrinking today.

“There is the red deer that’s showing a decrease in body size. And there is the California squirrel that is showing a reduced body size, more in correlation to reduced precipitation,” she says.

During the last massive global warming period, she says, we didn’t see a lot of mammals actually go extinct.

But this time, D’Ambrosia says, we’re warming up at a much faster rate, and some animals may not have enough time to adapt.