When the carbon dioxide content of the atmosphere rises, the Earth not only heats up, but extreme weather events, such as lengthy droughts, heat waves, heavy rain and violent storms, may become more frequent. Whether these extreme climate events result in the release of more CO2 from terrestrial ecosystems and thus reinforce climate change has been one of the major unanswered questions in climate research. It has now been addressed by an international team of researchers working with Markus Reichstein, Director at the Max Planck Institute for Biogeochemistry in Jena. They have discovered that terrestrial ecosystems absorb approximately 11 billion tons less carbon dioxide every year as the result of the extreme climate events than they could if the events did not occur. That is equivalent to approximately a third of global CO2 emissions per year.