Less gloopy oceans slow climate change

THE thinner the better. Our changing climate will make the oceans less viscous – good news as it means they will be much better at burying atmospheric carbon out of harm’s way on the seabed. It won’t stop global warming, but it will slow it, says Jan Taucher of the Helmholtz Centre for Ocean Research in Kiel, Germany. Much of the carbon dioxide we release into the air goes into the sea and is taken up by organisms. When they die, some of it sinks. To replace this buried carbon, the oceans absorb more from the air, curbing climate change. Global warming may boost this process, says Taucher. Warm water is less viscous, so carbon sinks 5 per cent faster per degree of warming. Taucher added this viscosity effect to a model of the ocean and ran it until the year 4000, with emissions falling after 2100. The oceans took in 17 per cent more carbon dioxide than expected, cutting warming by 8 per cent – although the world still warmed by 6 °C (Global Biogeochemical Cycles, doi.org/rzr). However, the deep oceans seem to be warming faster than expected, says Taucher. He estimates the drop in viscosity could cut warming by between 0.1 °C and 0.2 °C within 100 years.