According to the report, land ecosystems store approximately 2,800 billion tons of organic carbon – around 400 billion tons more than previous studies have revealed. This higher number is due mainly to higher estimates of organic material in soils. 

High retention is shown with a higher relief upwards. Areas where residence times depend on temperature are yellow (weak) to red (strong), those depending stronger on precipitation turquoise to blue. Illustration by Nuno Carvalhais.
High retention is shown with a higher relief upwards. Areas where residence times depend on temperature are yellow (weak) to red (strong), those depending stronger on precipitation turquoise to blue. Illustration by Nuno Carvalhais.

Plants play a crucial role in the global climate system, removing the greenhouse gas carbon dioxide from the air and converting it into carbohydrates. Carbon is stored then for several years or even many decades in terrestrial ecosystem before it is converted back into CO2 by decomposition, and returned to the atmosphere. According to the report, it takes about 23 years on average, but less in tropics (15 years) and much more in the tundra (255 years) before a carbon atom is released back into the atmosphere, according to the report.

As expected, this turnover time is strongly dependent on temperature: the warmer it is the faster dead biomass degrades. However, precipitation also showed to be just as important in determining how quickly carbon is converted in an ecosystem. The report shows that carbon turnover time decreases when precipitation increases.

The study was led by Nuno Carvalhais at the Max Planck Institute for Biogeochemistry, Jena, Germany and the Department of Environmental Sciences and Engineering, New University of Lisboa in Portugal.