Warming of just 2°C will release billions of tons of soil carbon

A new study suggests that 2°C global warming will result in the release of about 230 billion tons of carbon from the soil. This conclusion was made by an international group of scientists led by the University of Exeter, the results of the study are published in the journal Nature.

Global soils contain two to three times more carbon than the atmosphere, and warmer temperatures accelerate decomposition. This reduces the amount of time CO2 spends in the soil, changing the way the carbon cycle in the soil changes.”

A new international study shows the sensitivity of the soil carbon cycle to global warming and therefore halves the uncertainty in future projections of climate change.

An estimated 2°C warming (above pre-industrial levels) releases 230 billion tonnes of carbon. This is four times the total emissions in China and twice in the United States over the past 100 years.

“Our study excludes the most extreme forecasts, but nevertheless assumes significant losses of carbon in the soil due to climate change with a warming of only 2°C. And this does not even include the loss of more carbon from melting permafrost.” explains study co-author Dr. Sarah Chadburn of the University of Exeter.

This effect is a so-called “positive feedback” – when climate change causes side effects that contribute to further climate change, worsening the situation.

It is the response of soil carbon to climate change that represents the largest area of ​​uncertainty in understanding the carbon cycle in climate change projections. To solve this problem, the researchers used a new combination of observational data from Earth systems. They model the climate and carbon cycle and then make predictions about climate change.

Current models assume an uncertainty of about 120 billion tonnes of carbon at an average global warming of 2°C. The latest research reduces this uncertainty to about 50 billion tons of carbon. In this way, scientists have reduced the uncertainty in this response to climate change, which is vital for calculating an accurate global carbon budget for the Earth.

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