Soils play an important role in balancing the climate.
It acts as a carbon sink, sequestering CO2 from the atmosphere into the soil organic carbon.
Land use change, degradation processes and climate change often result into soil organic carbon being released from soil to the atmosphere, decreasing the soil’s capacity to store CO2.
Soil erosion, which is likely to be exacerbated due to more intense precipitation expected as a result of climate change, leads to the displacement of soil and the organic carbon within it.
“We estimated that accelerated soil erosion in EU agricultural land – due to more intense precipitation – will lead to a 35% increase in eroded carbon in the period 2016-2100. This is likely to exacerbate carbon losses –as emissions of CO2 – from agricultural land to the atmosphere, thus increasing the effect of climate change”, said lead author Emanuele Lugato.
There is evidence that climate change is already causing net losses of organic carbon from soil across the EU, but the extent and consequences of this disruption to the carbon stock is still uncertain.
Soil erosion not likely to lead to a future carbon sink
There is a scientific debate on whether soil erosion creates a net source or a net sink of CO2 – in other words, whether it leads to more CO2 being captured or more CO2 being released from soils.
“Some scientists support the idea that soil erosion leads to more carbon being sequestered from the atmosphere. They argue that the eroded carbon can be deposited in places where it remains stored for a long time, thus creating a carbon sink”, Emanuele explains.
“Our results challenge this idea. Our approach takes into consideration a wide range of drivers and processes, which are necessary to predict future changes. Our model shows that when we do consider all these factors, soil erosion is not likely to lead to a carbon sink but, on the contrary, further increase the release of CO2 into the atmosphere”, concludes Emanuele.
It is important that policies governing the agricultural sector continue to support measures that help prevent soil erosion while maintaining or increasing soil organic carbon.
This has implications for soil ecosystem services and, in particular, on the climate change mitigation capacity of agricultural land.
The consistent biogeochemistry-erosion model framework used in this study aims to quantify the impact of future climate change on the carbon cycle taking account of accelerated water erosion.
This tool can be used to estimate the impact of policies targeting soil protection, agriculture (in particular the ongoing review of the CAP) and climate (e.g. the LULUCF Regulation).