Global soil organic carbon removal by water erosion under climate change and land use change during AD 1850–2005
<p>Erosion is an Earth system process that transports carbon laterally across the land surface and is currently accelerated by anthropogenic activities. Anthropogenic land cover change has accelerated soil erosion rates by rainfall and runoff substantially, mobilizing vast quantities of soi...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-07-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/15/4459/2018/bg-15-4459-2018.pdf |
| Summary: | <p>Erosion is an Earth system process that transports carbon laterally across
the land surface and is currently accelerated by anthropogenic activities.
Anthropogenic land cover change has accelerated soil erosion rates by
rainfall and runoff substantially, mobilizing vast quantities of soil organic
carbon (SOC) globally. At timescales of decennia to millennia this mobilized
SOC can significantly alter previously estimated carbon emissions from land
use change (LUC). However, a full understanding of the impact of erosion on
land–atmosphere carbon exchange is still missing. The aim of this study is
to better constrain the terrestrial carbon fluxes by developing methods
compatible with land surface models (LSMs) in order to explicitly represent
the links between soil erosion by rainfall and runoff and carbon dynamics.
For this we use an emulator that represents the carbon cycle of a LSM, in
combination with the Revised Universal Soil Loss Equation (RUSLE) model. We
applied this modeling framework at the global scale to evaluate the effects
of potential soil erosion (soil removal only) in the presence of other
perturbations of the carbon cycle: elevated atmospheric CO<sub>2</sub>, climate
variability, and LUC. We find that over the period AD 1850–2005
acceleration of soil erosion leads to a total potential SOC removal flux of
74±18 Pg C, of which 79 %–85 % occurs on agricultural land
and grassland. Using our best estimates for soil erosion we find that
including soil erosion in the SOC-dynamics scheme results in an increase of
62 % of the cumulative loss of SOC over 1850–2005 due to the combined
effects of climate variability, increasing atmospheric CO<sub>2</sub> and LUC.
This additional erosional loss decreases the cumulative global carbon sink on
land by 2 Pg of carbon for this specific period, with the largest effects
found for the tropics, where deforestation and agricultural expansion
increased soil erosion rates significantly. We conclude that the potential
effect of soil erosion on the global SOC stock is comparable to the effects
of climate or LUC. It is thus necessary to include soil
erosion in assessments of LUC and evaluations of the terrestrial carbon
cycle.</p> |
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| ISSN: | 1726-4170 1726-4189 |