Loss of soil carbon due to climate change will be 'huge'

https://www.eurekalert.org/pub_releases/2016-11/nioe-los113016.php

Public Release: 30-Nov-2016
Loss of soil carbon due to climate change will be 'huge'
Netherlands Institute of Ecology (NIOO-KNAW)

55 trillion kilograms: that's how much carbon could be released into the atmosphere from the soil by mid-century if climate change isn't stopped. And all in the form of greenhouse gases such as CO2 and methane. Tom Crowther (NIOO-KNAW) and his team are publishing the results of a worldwide study into the effects of climate change on the soil in the issue of Nature that comes out on 1 December.

For decades, scientists have speculated that rising global temperatures might affect the huge amount of carbon stored in the soil. Carbon is one of the building blocks of life, and nowhere on land are larger carbon stocks to be found than in the soil.

Thousands of studies worldwide have produced mixed signals on whether the soil's storage capacity will decrease as the planet warms, or perhaps even increase.

A new, worldwide study led by researcher Tom Crowther (Netherlands Institute of Ecology NIOO-KNAW, formerly of Yale University) finally answers that question: "The effect will be roughly equivalent to adding another industrialized country to the planet, the size of the United States."

"If climate change isn't stopped, an additional 55 trillion kilograms of carbon will be released into the atmosphere by the year 2050", says Crowther. It will be released in the form of CO2 or methane: greenhouse gases, speeding up what would otherwise have been a natural process.

"It's about 17 percent more than the projected emissions due to human-related activities during that period", says Crowther. And those greenhouse gases could further accelerate global warming, which would have even more of an impact on the soil: a full-fledged domino effect.

So why was this not obvious all along? Because researchers were looking in the wrong places, argues Crowther. "With data from more than 40 institutes around the world, covering 20 years, our scope is now finally worldwide."

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The release of those stocks - built up over thousands of years - will be accelerated by climate change because it stimulates soil life. Micro-organisms in the soil, in particular, will become more active.

Factors that could slow down this process, or speed it up even further, should also be considered. With more CO2 in the atmosphere, for instance, plant growth will also be accelerated. That's why the international researchers have reserved a margin for the extra emissions: between 12% and 17%.

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