Humans causing erosion comparable to world’s largest rivers and glaciers

A new study finds that large-scale farming projects can erode the
Earth’s surface at rates comparable to those of the world’s largest
rivers and glaciers.

Published online in the journal Nature Geoscience, the research offers
stark evidence of how humans are reshaping the planet. It also finds
that – contrary to previous scholarship – 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 (UBC) 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,” says Koppes, who
conducted the study with David Montgomery of the University of
Washington.

In some cases, the researchers 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.”

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

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

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

View the study at:
www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo616.html

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