Scientists have discovered a brilliant new way to measure ocean warming.
Researchers say the “hack” works because sound travels faster in hot water.
The team looked at Sonic data from the Indian Ocean exposed by the earthquake over a 10-year period.
Scientists have found that sound waves are increasing in speed as the oceans warm due to global warming.
Their new system shows that the decade-long warming trend in the Indian Ocean was much higher than previous estimates.
It is important for climate scientists to have accurate information about the warming of our oceans.
They understand that 90% of the energy trapped in our atmosphere by greenhouse gases is absorbed by the oceans.
But having accurate temperature measurements, in many places and at depth, is the biggest challenge.
Deployment of approximately 4,000 autonomous devices Argo floats That capture temperature information helped greatly, but to our knowledge there are large gaps.
This is especially true in relation to what happens in the water at depths of more than 2,000 meters.
But now the team of researchers has developed a very different approach, which takes advantage of the fact that the speed of sound in seawater depends on temperature.
The idea was first proposed and tested using sound waves created by scientists in the late 1970s.
However, concerns about the impact of these sounds on marine mammals and rising costs have abandoned this idea.
The new approach involves the use of naturally produced sound waves that occur during an underwater earthquake.
Scientists studied data on more than 4,000 vibrations that occurred in the Indian Ocean between 2004 and 2016.
The team then searched for “repeaters”, earthquakes with almost identical appearance and power.
By measuring how long it took for these slow-moving signals to travel from Indonesia to an observatory on the island of Diego Garcia, they were able to make changes in temperature across the ocean over a 10-year period. .
“It takes half an hour to travel from Sumatra to Diego Garcia,” Dr. Wenbo Wu, a leading writer at the California Institute of Technology, told the BBC.
“The deep sea temperature change between Sumatra and Diego Garcia will vary by a few tenths of a second during this half-hour voyage.
“Because we can measure these variations so accurately, we can predict small changes in the average temperature of the deep ocean, in this case one tenth of a degree.”
The author says that this system has some key advantages as it can provide a large average temperature over a 3,000 km route from Sumatra to Diego Garcia, which minimizes the influence of local fluctuations, especially as it sets more precisely over the ocean.
This method is very inexpensive because it uses data already collected, and it is sensitive to temperatures deeper than the current limit of 2,000 meters.
Scientists in their research have shown that warming in the Indian Ocean in the decade they studied is higher than previously estimated.
However, there are some important caveats in the paper.
“It is important to emphasize that this is a decision that applies to this particular region and this particular decade,” Dr. Wu said.
“We still need to use our method in many more regions and at different time scales to assess whether there is any systematic underestimation or overestimation of the deep-sea trend globally.
“Any decision in this direction will be made very soon.”
For this idea to work globally, scientists will need access to underwater recipients.
Now, the research team is working with data collected by a powered hydrophone network United Nations Comprehensive Nuclear-Test-Ban Treaty Organization, Which hears underwater nuclear explosions.
Dr. Wu explained that these hydrophones pick up signals from the 10,000 shallow submarine earthquakes that occur worldwide each year.
“These data contain information about deep ocean temperature change – we are waiting to extract it.”
The The study has been published In the journal Science.
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