Scientists have found a clever new way of measuring ocean warming, using sound waves from undersea earthquakes. The researchers say the “hack” works because sound travels faster in warmer water. The team looked at sonic data from the Indian Ocean emitted by tremors over a 10-year period. As the seas have warmed due to global heating, the scientists have seen the sound waves increase in speed. These hydrophones pick up signals from many of the 10,000 shallow submarine earthquakes that occur globally every year. Right now, a research team is working with data collected by a hydrophone network operated by the United Nations Comprehensive Nuclear-Test-Ban Treaty Organization, which is listening for underwater nuclear explosions. In their research, the scientists showed that warming in the Indian Ocean over the decade that they studied was greater than previously estimated.
By Matt McGrath. BBC News. September 17, 2020.