Climate change: Earthquake 'hack' reveals scale of ocean warming

The deployment of around 4,000 autonomous devices called Argo floats that capture temperature information has helped enormously, but there are big gaps in our knowledge.

Image copyrightGallo ImagesImage caption Researchers recorded the time taken for sound waves to register on Diego Garcia after travelling across the Indian Ocean The team then looked for pairs of "repeaters", earthquakes with almost identical origins and power.

By measuring how long these slow-moving signals took to travel across the waters from Indonesia to a monitoring station on the island of Diego Garcia, they were able to work out the changes in temperature for the whole of the ocean over the 10-year period.

"It takes sound waves about half an hour to travel from Sumatra to Diego Garcia," lead author Dr Wenbo Wu from the California Institute of Technology told BBC News.

The author says the system has some major advantages, as it is able to provide a large-scale average temperature along the 3,000km path from Sumatra to Diego Garcia, which reduces the influence of local fluctuations, essentially making it more accurate over the ocean as a whole.

Image copyrightGetty ImagesImage caption Students in Indonesia rehearse for a tsunami, an ever present danger because of earthquakes The method is also quite cheap, as it uses data that's already being gathered, and is sensitive to temperatures deeper than the current restriction of 2,000m.

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