Rock weathering in mountains with moderate erosion revealed as key carbon sink

Rock weathering in mountains with moderate erosion revealed as key carbon sink
by Robert Schreiber
Munich, Germany (SPX) Mar 11, 2024

A pivotal discovery by researchers from Ludwig-Maximilians-Universitat Munchen and the German Research Centre for Geosciences has illuminated a crucial component of Earth's natural climate regulation system. The team, led by LMU geologist Aaron Bufe and Niels Hovius, delved into the mechanisms through which rock weathering contributes to atmospheric carbon dioxide (CO2) regulation over extensive geological periods, thereby influencing Earth's climate.

The study's revelations highlight the significant role of rock weathering in Earth's "thermostat." This process involves the interaction of rocks with water and wind, leading to the removal of CO2 from the atmosphere through the formation of calcium carbonate from silicate weathering. Conversely, the weathering of other materials, such as carbonates and sulfides, can release CO2 back into the atmosphere.

Through sophisticated modeling of weathering processes across diverse geographical areas, including Taiwan and New Zealand, the research team discovered consistent patterns that underscore common underlying mechanisms. Their findings challenge previous assumptions, demonstrating that the most efficient CO2 capture occurs in low-relief mountain ranges with moderate erosion rates, approximately 0.1 millimeters per year, rather than in regions with the highest erosion rates.

This counterintuitive result indicates that optimal CO2 sequestration happens in environments where rapid weathering of carbonates and sulfides has been balanced by abundant and efficiently weathering silicate minerals. On the other hand, extremely high or low erosion rates tend to decrease CO2 capture, with high rates even turning weathering into a net source of atmospheric CO2.

Such insights suggest that low-relief mountain ranges, such as the Black Forest in Germany or the Oregon Coast Range in the United States, are among the most significant carbon sinks on our planet. This understanding shifts the perspective on how geological processes influence the global climate over millennia, highlighting the intricate relationship between erosion rates and atmospheric CO2 levels.

Aaron Bufe emphasizes the need for future research to expand on these findings by incorporating the roles of organic carbon sinks and the weathering processes occurring in floodplains, to achieve a more comprehensive understanding of erosion's impact on the Earth's climate system.

Research Report:CO2 drawdown from weathering maximized at moderate erosion rates