Natural versus anthropogenic erosion in Central Brazil, a confrontation of time and space scales

<p>Land degradation resulting from increased continental surface erosion is a worldwide and systemic phenomenon due to human activities. Already fragile, the intertropical zone is likely to be further affected by climate change and increased aridity, an aggravating factor of soil erosion and land degradation. A major challenge is thus to provide the necessary knowledge to not only deepen our understanding of the Earth system and its critical thresholds but also to help achieving sustainable development goals. Understanding the factors that control the properties and processes of the critical zone, and especially what will be its responses to ongoing climate and land use changes, requires multidisciplinary efforts to tackle time scales that are compatible with morphogenesis and soil development as well as environmental disturbances of anthropogenic origin. Due to its prominent ecological importance, the Brazilian Cerrado biome is an ideal natural laboratory were to gauge the consequences of recent and strong human activities on continental surface erosion. We focused on the region of Bras&#237;lia where our approach allows confronting the temporal scales of long-lived and stable cosmogenic nuclides with that of short-lived radioactive isotopes, through a comparison of natural and anthropogenically disturbed land surfaces. Our results indicate that long-term, background denudation rates are lower than 10&#160;mm&#160;kyr^-1whereas recent erosion rates due to human activities may reach rates at least 160 times higher, exceeding by far the sustainability rates of the soil resource.</p>