The importance of the carbon cycle

Researchers from USC and Nanjing University in China have documented evidence suggesting that part of the reason that Earth has become neither sweltering like Venus nor frigid like Mars lies with a built-in atmospheric carbon dioxide regulator — the geologic cycles that churn up the planet’s rocky surface.

Scientists have long known that “fresh” rock pushed to the surface via mountain formation effectively acts as a kind of sponge, soaking up the greenhouse gas CO₂. Left unchecked, however, that process would simply deplete atmospheric CO₂ levels to a point that would plunge Earth into an eternal winter within a few million years during the formation of large mountain ranges like the Himalayas — which has clearly not happened.

“Our presence on Earth is dependent upon this carbon cycle. This is why life is able to survive,” said Mark Torres, lead author of a study disclosing the findings that appears in Nature. Torres and his colleagues studied rocks taken from the Andes mountain range in Peru, and found that weathering processes affecting rocks released far more carbon than previously estimated — motivating them to consider the global implications of CO₂ release during mountain formation.

Using marine records of the long-term carbon cycle, the researchers reconstructed the balance between CO₂ release and uptake caused by the uplift of large mountain ranges and found that the release of CO₂ release by rock weathering may have played a large, but thus far unrecognized, role in regulating the concentration of atmospheric carbon dioxide over the last roughly 60 million years.