Despite what photos suggest, Earth is not perfectly round. Our home planet is actually a lumpy “oblate spheroid” that bulges slightly at the equator and flattens at the poles, like a ball of clay smushed between your fingers. But as fossil fuel pollution alters Earth’s climate, it’s altering the planet’s shape as well.

That’s according to a study published last month in the journal JGR Solid Earth. The findings suggest that the overall shape of Earth’s solid surface is becoming rounder at an accelerated rate as rising global temperatures drive polar ice melt. While the shape of the planet has never been fixed, this rapid change underscores the power of human-driven warming.

“These findings are important because they help scientists understand how the planet responds to melting glaciers and shifting water,” Christopher Kotsakis, a professor of geodesy at the Aristotle University of Thessaloniki in Greece and the study’s author, wrote in his study. “This kind of knowledge is essential for tracking climate change and its impact on Earth’s long-term behavior.”

Kotsakis set out to determine whether the recent acceleration of polar ice melt and resulting redistribution of meltwater have measurably changed the shape of Earth’s solid surface—specifically the flatness of the poles and bulging around the equator. He developed a new method for analyzing data from the Global Navigation Satellite System (GNSS), which directly measures surface motion.

5 to 1 millimeter) per year. At the same time, Earth’s equatorial bulge appears to be shrinking at a similar rate.

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