From Soil Erosion’s Past Come Clues to Its Future Impact on Climate Change

Our planet is so interconnected that one country’s problems are rarely its own. Especially when it comes to the growing global demand for food, they become everyone’s concern and the geopolitical risks involved are one thing driving Dr. Jean-Philippe Jenny’s research. His mission is to understand human impact on soil erosion around the world and its consequences for both the food supply and climate change. Human activities like the construction of dams, intensive agriculture or deforestation contribute to the movement of soils and their runoff into waterways. This can degrade the quality of agricultural land and also plays a role in the carbon cycle by displacing carbon stored in the landscape. To accurately predict future soil erosion rates, Dr. Jenny needs to reconstruct their past. Since measurements of soil transport have been taken only in recent years, he will turn to the information stored in lake sediments, like archives of accumulated soils, washed in over time.

Computer models of soil erosion processes do exist, but they do not address the changing dynamics of long-term human influence. Dr. Jenny’s interdisciplinary approach will, for the first time, unite predictive ecosystem modeling with the study of the past through lake sediments and allow him to verify the impact of the last 100 years of human intervention on the landscape. With extensive open source datasets on European lake sediments, climate and land use, he will analyze the effects of human activities—major construction, farming, urbanization—on erosion rates over time. Samples from lakes on six continents will allow him to understand erosion in a range of very different environments and to quantify the dynamics of agricultural soil loss. This work will lead to the first database on highly resolved changes in mineral and organic composition devoted to studying lake archives from the regional to the global level.

With the data collected, Dr. Jenny will also explore soil erosion’s impact on the carbon cycle. Carbon is stored in the ground, following decomposition of organic matter, for example. When soil is transported, the carbon it holds may be transferred to lake sediments, or escape into the atmosphere, potentially contributing to climate change. However, little is known of this process and models of the carbon cycle generally neglect the input of erosion and of bodies of water. Dr. Jenny’s goal is to find out whether soil erosion will increase carbon transfer and affect the carbon cycle. “Sediment records from lakes can tell us about the production and emission of carbon from the lake itself into the atmosphere,” Dr. Jenny explains, “but they also tell us how much of that carbon came from the soil. So, we can identify if certain practices like agriculture or forestry are connected to an increased rate of transport of carbon. If so, this would be a factor that is not considered in current carbon cycle models.”

Bringing together environmental and geosciences will help him create the tools needed to better assess the carbon cycle on multiple scales. Ultimately, Dr. Jenny will take the connections he uncovers between soil loss and carbon storage and integrate them into ecosystem models. The project will also help identify the main sources of soil erosion, a first step toward protecting productive croplands and minimizing the impact on the carbon cycle. The extreme weather expected with climate change, like torrential rain and droughts, will exacerbate soil erosion. Meanwhile, the global food demand is expected to double over the next 50 years. No country can afford to look the other way and Dr. Jenny’s research may provide the tools to find solutions.

Scientific title : Reconstructing Rates Of Changes In Global Soil Erosion And Effects On Carbon Cycle

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From Soil Erosion’s Past Come Clues to Its Future Impact on Climate Change

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