Earth warming to climate tipping point, warns study
A warmer world will release vast volumes of carbon into the atmosphere, potentially triggering dangerous climate change. Projections that an increase of 1C will release an additional 55 billion tonnes of carbon into the atmosphere by 2050. This could trigger a "positive feedback" and push the climate system past the point of no-return.
Previous assessments have not taken carbon released by soil into account. In their Nature paper, an international team of scientists said that the majority of the Earth's terrestrial store of carbon was in the soil.
They warned that as the world warmed, organisms living in the planet's soils would become more active, resulting in more carbon being released into the atmosphere - exacerbating warming.
"There have been concerns about this positive feedback for a long, long time," said lead author Thomas Crowther, who conducted the research while based at Yale University, US, but now at the Netherlands Institute of Ecology.
"For the past two or three decades there have been literally thousands of studies trying to address this topic and trying to identify whether there are going to be increases or decreases in carbon uptake of the soil in relation to warming or increases in carbon loss."
Dr Crowther said the uncertainty surrounding the exchange of carbon between the atmosphere and the planet's soils had led to "sizeable differences in the projections of future climate conditions".
He told BBC News: "We are the first study to take a global perspective and then map the variability and able to say that in these areas there are going to be huge losses and in these areas there are going to be some gains.
"Using this approach we can get a robust idea of the whole picture. We show that, actually, the losses are going to be really considerable."
Using data stretching over 20 years from 49 sites across the globe, the team observed that global carbon stocks would fall by up to 55 petagrams (55 billion tonnes) under a business-as-usual scenario, which is roughly equivalent to adding the emissions from a nation the size of the US.