Ocean warming: severely underestimated?

October 9, 2014

Two studies recently published in the journal Nature Climate Change suggest ocean warming has been drastically underestimated. New data suggests our understanding of warming from 1970-2004 in oceans at the upper levels of the Southern Hemisphere needs to be accelerated.

Oceans absorb 90 per cent of the excess heat on Earth, and the Southern Hemisphere accounts for 60 per cent of the world’s oceans. The new data, from climate models and satellites, therefore suggests that the planet is warming much faster than we thought. Lead author of one of the papers, oceanographer Paul Durack, said: “This underestimation is a result of poor sampling prior to the last decade and limitations of the analysis methods that conservatively estimated temperature changes in data-sparse regions”.

Things began to change in 2004, when researchers were able to collect more accurate measurements using robotic devices called Argo floats. 3,600 of these devices were deployed, relaying information on heat stored in the upper layers of ocean currents across the globe.

Argo measurements have revealed that, from 2005, the upper-ocean has continued to warm. Felix Landerer of NASA, contributor to both studies, said: “Using the latest available observations, we’re able to show that this upper-ocean warming and satellite measurements are consistent”. This is important work, as determining how fast the oceans are warming is linked to both how quickly the atmosphere is warming, and how much sea levels will rise.