A study suggests long-term influences of human activities on global soil erosion. Human land use changes have accelerated soil erosion rates around the world, affecting soil productivity, river ecosystems, and biogeochemical cycles. A lack of spatiotemporally resolved empirical data spanning millennial time scales limits understanding of when human activities began to influence soil erosion rates on a global scale as well as the ability to predict soil erosion responses to long-term climate and land cover changes. Jean-Philippe Jenny and colleagues analyzed pollen samples and radiocarbon dates from 632 lake watersheds to reconstruct land cover changes and sediment accumulation rates (SAR) during the past 12,000 years. Thirty-five percent of the lake sites exhibited significant increases in SAR. The authors identified a sharp increase in global SAR, along with an increased fraction of lakes exhibiting elevated SAR, beginning approximately 4,000 years ago. This increase coincided with a decrease in the proportion of arboreal pollen in lake sediments, an indicator of deforestation. In 70% of the watersheds studied, land cover change was the main driver of soil erosion. The results suggest that land cover changes drove the increase in soil erosion rates, and that human activities began to alter global soil erosion well before industrialization, according to the authors.
Article #19-08179: "Human and climate global-scale imprint on sediment transfer during the Holocene," by Jean-Philippe Jenny et al.
MEDIA CONTACT: Jean-Philippe Jenny, Institute national de la recherche agronomique, Thonon, FRANCE; tel: +33-4-79-75-86-49, +33-320261424, +33-7-67-88-61-20; e-mail: Jean-Philippe.Jenny@inra.fr
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Journal
Proceedings of the National Academy of Sciences