Even if we meet the Paris Agreement's goal of limiting global warming to 2 degrees, the change in temperature will have a major impact on the coal reserves stored in the world's soils. 

- When it gets warmer, there are more bacteria that break down the carbon found in the soil, especially in cold areas where there is permafrost, says Gustaf Hugelius, natural geographer at Stockholm University and one of the co-authors of the study published in the scientific journal Nature Communications. 

Enormous amounts of coal in the ground

The researchers believe that there is about three times as much carbon dioxide in the soil as there is already in the atmosphere, and much is stored in the colder regions because the decomposition processes are slower there.  

Global warming as a result of greenhouse gas emissions can cause these sites to go from being coal storage sites to carbon dioxide emitters.

The "Arctic amplification"

Due to the so-called "Arctic amplification", which means that warming is twice as fast in the Arctic, the temperature will rise by about four degrees here when the earth is heated by an average of two degrees.

- Researchers have previously estimated that we can emit another 430 billion tons of carbon before we reach a warming of 2 degrees.

The new forecast means that we may actually only have half.

This also makes it more important to reduce human emissions of greenhouse gases as soon as possible, says Birgit Wild, natural geographer at Stockholm University.  

Combined models

The researchers have combined data from climate models with actual measurements of how carbon reacts to temperature changes in soil holes in several different places around the world.

But exactly how quickly these emissions will occur, the researchers' models can not predict.  

- These calculations do not take into account that the vegetation becomes greener at the same time, so there will be other processes that counteract it to some extent, says Gustaf Hugelius.

More about carbon dioxide in the atmosphere in the world of Science "Technicians who want to hack the climate", Monday 20.00 on SVT2 or on SVT play.