Are landslides an important climate factor?

Are landslides an important climate factor? (Photo: R. Emberson, GFZ).

26.09.2016: "These ideas have the potential to transform how we understand weathering processes": This is the explanation of the editors of the science journal Earth Surface Dynamics for electing an article, published by a team around the PhD student Robert Emberson, GFZ section Geomorphology, as a „highlight paper“.

The study „Oxidation of sulphides and rapid weathering in recent landslides“, published last friday, investigates the link between landslides and an enhanced chemical weathering . Previous works mostly look at the process of weathering in mountain belts from a large spatial scale and describe it as a steady process within model simulations. They disregard any local differences in physical or chemical weathering and their varying temporal scales.

In their new study as well as in another paper published earlier this year, the scientists show that landslides are an important local factor of weathering. They even describe them as „weathering reactors“ with an enormous impact on the big picture of weathering in mountain belts. For their study the scientists worked in the field in Taiwan, closely together with local colleagues. For their previous study, they organized field work in New Zealand.

Landslides as a source or sink for CO2?

Landslides expose a large amount of rock to the free air and thereby make it available for physical and chemical weathering. The weathering of the silicate rock share, like feldspar and clay minerals, extracts CO2 from the atmosphere, which is why this form of chemical weathering is regarded as an important climate factor within long-term climate studies, for quite some time. The new study shows: besides silicate weathering, landslides also enhance sulphide weathering. When the resultant sulphuric acid breaks down exposed carbonate, this form of chemical weathering imports CO2 into the atmosphere, and thus works as a contrawise effect.

The scientists now try to find out how to quantify these processes. Then it will be possible to  estimate if the two forms of chemical weathering in sum introduce CO2 into the atmosphere, so if they turn out as a net source for the greenhouse gas CO2, or rather remove CO2 from the atmosphere and thereby act as a sink for the greenhouse gas. If landslides thus are an important climate factor is therewith object of further research. (ak)

Highlight paper: Emberson, R., Hovius, N., Galy, A., Marc, O., 2016. Oxidation of sulphides and rapid weathering in recent landslides. Earth Surface Dynamics, doi:10.5194/esurf-2016-31

Previous paper on the topic: Emberson, R., Hovius, N., Galy, A., Marc, O., 2016. Chemical weathering in active mountain belts controlled by stochastic bedrock landsliding. Nature Geosciences 9, 42-45. doi:10.1038/ngeo2600