Large-scale farming projects can erode the Earth's surface at rates comparable to those of the world's largest rivers and glaciers, a new study finds.

The finding is not a big surprise. In 2004, researchers concluded that human activity causes 10 times more soil erosion than all natural processes combined.

The new study, published online in the journal Nature Geoscience, "offers stark evidence of how humans are reshaping the planet," the scientists said in a statement. It also finds that - contrary to previous research - rivers are as powerful as glaciers at eroding landscapes.

"Our initial goal was to investigate the scientific claim that rivers are less erosive than glaciers," says Michele Koppes, a professor of geography at the University of British Columbia and lead author of the study. "But while exploring that, we found that many of the areas currently experiencing the highest rates of erosion are being caused by climate change and human activity such as modern agriculture," Koppes said.

Koppes and colleagues created an updated database of erosion rates for more than 900 rivers and glaciers worldwide.

In some cases, they found large-scale farming eroded lowland agricultural fields at rates comparable to glaciers and rivers in the most tectonically active mountain belts.

"This study shows that humans are playing a significant role in speeding erosion in low lying areas," says Koppes. "These low-altitude areas do not have the same rate of tectonic uplift, so the land is being denuded at an unsustainable rate."

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