At the end of the last Ice Age, around 10,000 years ago, the melting of massive glaciers may have done more than just raise sea levels.
According to new research from the University of Colorado Boulder, this meltwater may have helped speed up the movement of Earth’s continents and fueled volcanic eruptions—especially in places like Iceland.
Using powerful computer simulations, scientists Tao Yuan and Shijie Zhong recreated Earth’s conditions from about 26,000 years ago.
Back then, a huge glacier called the Laurentide Ice Sheet covered much of North America. As it melted, oceans rose by about 1 centimeter per year. But something else may have been happening under the surface.
The researchers found that the weight of this melting ice changed how Earth’s crust moved—not just vertically, as previously thought, but also horizontally.
Their study, published in Nature, shows that as the ice disappeared, the North American tectonic plate may have sped up by about 25%.
At the same time, the Mid-Atlantic Ridge—a major underwater mountain range where new ocean crust forms—may have spread faster by as much as 40%.
This is surprising because scientists have long believed that tectonic plate movements happen slowly over millions of years, driven mainly by heat and pressure deep inside the Earth.
While that’s still true, this study suggests that melting ice sheets can also play a powerful role over much shorter time periods, like tens of thousands of years.
To understand this, it helps to imagine Earth as a memory foam mattress. When you lie on it, the foam sinks under your weight.
When you get up, the foam slowly returns to its original shape. In a similar way, when massive glaciers melt, the land underneath them begins to rise again. That’s happening even today—land around Canada’s Hudson Bay is still bouncing back, rising about 1 centimeter each year.
But the changes weren’t just up and down. As the glaciers melted and weight shifted into the oceans, this also appears to have nudged the tectonic plates sideways, speeding up their movement and even boosting volcanic activity. In Iceland, which sits along the Mid-Atlantic Ridge near Greenland, this may explain a burst of volcanic eruptions seen at the end of the last Ice Age.
Today, the glaciers in Greenland are melting again, although not yet fast enough to noticeably shift tectonic plates. However, if the melting continues or speeds up in the coming centuries, it could once again stir volcanic activity in Iceland and affect the seafloor spreading nearby.
The researchers say this finding shows that Earth’s icy and rocky layers are more connected than we once thought—and that today’s melting glaciers could have powerful effects far beyond rising seas.
