Earth Tectonics Led to Glaciers on Greenland

Climate change and warming temperatures are currently melting the ice on Greenland, but this region was not always one giant ice sheet. In a new study, researchers explain that Earth tectonics and other interior processes led to the glaciers that we see on Greenland today.

The Northern Hemisphere was largely free of ice for more than 500 million years. It wasn't until 2.7 million years ago that the Arctic, including Greenland, started to see large-scale glaciations, thanks to three separate mechanisms of Earth tectonics. According to the study, the entirety of Greenland was physically lifted up, making it so mountain peaks reached the high atmosphere's cold altitudes, and Greenland moved northward a significant amount - in part due to a shift of Earth's axis - which led to reduced solar irradiation in winter.

The findings were published in the journal Terra Nova.

First off, scientists at the German Research Centre for Geosciences GFZ, Utrecht University, the Geological Survey of Denmark and Greenland (GEUS) and the University of Oslo found evidence of Greenland uplift in samples of hot rocks underneath Iceland from Earth's deep mantle.

"These hot rocks flow northward beneath the lithosphere, that is, towards eastern Greenland," lead author Bernhard Steinberger explained in a statement. "Because the upwelling beneath Iceland - the Iceland plume - sometimes gets stronger and sometimes weaker, uplift and subsidence can be explained."

The East of Greenland was the first region to rise up, with its mountains being uplifted only during the last 10 million years - although, this process gained speed about five million years ago.

Seismological investigations also show that the lithosphere - composed of Earth's crust and upper mantle - in the East of Greenland is especially thin, only about 90 kilometers (56 miles) thick. By recreating conditions some 60 to 30 million years ago, researchers realized that the reasoning for this was because the Iceland plume was exactly beneath this part of Greenland during that time, making it susceptible to uplift. Plume material, for example, can flow up to a depth of less than 100 km (62 miles) and therefore lift up the lithosphere rather easily.

Consequently, Greenland moved as a tectonic plate, with a northward component of six degrees of latitude during the past 60 Million years, towards cooler regions.

What's more, this northward movement was amplified due to a 12-degree shift in the Earth's axis. Greenland subsequently moved another 18 degrees northward, with its mountain tops in the East staggeringly high, such that glaciers could finally form.

And after so much time, with Greenland finally boasting a massive ice sheet - the second-largest body of ice on Earth - it seems that its ice is now vanishing faster than previously thought. In the face of climate change, if it were to melt completely, it could raise our oceans by a whopping 20 fee.

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