Mountain Erosion Accelerates with Cooling Climate: Impact of Glaciers

Earth's mountains, while well understood in some ways, are poorly understood in others--especially when it comes to erosion. Now, scientists have taken a closer look at the coupling of climate and erosion on a global scale, revealing that under a cool climate, erosion rates increase significantly.

In order to learn a bit more about the effect of global cooling and glaciation on topography over the last three million years, the researchers compiled data from 18,000 rock samples. This allowed them to globally estimate temporal and spatial variations in erosion rates.

During mountain erosion, rocks travel from about 10 kilometers depth in the crust to the Earth's surface. During this process, the rocks cool from great depths to the surface. Thermochronology exploits small quantities of radioactive uranium contained in the rock decay in a time-dependent process. This data can converted into an erosion rate using computer models.

"On a global scale, erosion rates span four orders of magnitude in the last eight million years from one hundredth millimeter up to ten millimeters a year," said Todd Ehlers, one of the researchers in a news release.

The researchers found that six million years ago, increase of erosion rates was expressed at all latitudes, but was most pronounced in glaciated mountain ranges. This seems to suggest that glaciers played a significant role. They also discovered that erosion rates accelerated more in the last two million years with the most substantial changes at higher latitudes that have all been glaciated in the past few million years.

The findings have important implications for improving our understanding of the coupling between climate and erosion. More specifically, they show how a cooler climate can actually increase erosion rates.

The findings are published in the journal Nature.