Humans cause as much erosion as world’'s largest rivers and glaciers, geologists say

A new study finds that large-scale farming projects can erode theEarth's surface at rates comparable to those of the world's largestrivers and glaciers.

Published online in the journal Nature Geoscience, the research offersstark evidence of how humans are reshaping the planet. It also findsthat - contrary to previous scholarship - rivers are as powerful asglaciers at eroding landscapes.

"Our initial goal was to investigate the scientific claim that riversare less erosive than glaciers," says Michele Koppes, a professor ofgeography at the University of British Columbia (UBC) and lead author ofthe study.

"But while exploring that, we found that many of the areas currentlyexperiencing the highest rates of erosion are being caused by climatechange and human activity such as modern agriculture," says Koppes, whoconducted the study with David Montgomery of the University ofWashington.

In some cases, the researchers found large-scale farming eroded lowlandagricultural fields at rates comparable to glaciers and rivers in themost tectonically active mountain belts.

"This study shows that humans are playing a significant role in speedingerosion in low lying areas," says Koppes. "These low-altitude areas donot have the same rate of tectonic uplift, so the land is being denudedat an unsustainable rate."

Koppes says other significant causes of low-altitude erosion includeglacier melting caused by climate change and volcanic eruptions.

The highest erosion rates have typically been seen at high altitudeswhere tectonic forces pit rising rock against rivers and glaciers, saysKoppes, who with Montgomery created with an updated database of erosionrates for more than 900 rivers and glaciers worldwide, documented overthe past decade with new geologic measuring techniques.

Contrary to previous scholarship, they found that rivers and glaciers inactive mountain ranges are both capable of eroding landscapes by morethan one centimetre per year. Studies had previously indicated thatglaciers could erode landscapes as much as 10 times faster than rivers,Koppes says.

Source: University of British Columbia