Undersea Earthquakes Reveal Sound Warming Info
Climate change feels like something that's happening to the atmosphere but most of the action is actually at sea about ninety percent of the heat that gets trapped by greenhouse gases is absorbed by the ocean. So it's it's really important to track that energy and time it system and check the warming the ocean. Un kelly's an oceanographer at caltech. Of course the ocean is really big and taking its temperature is hard. Satellites give information about the surface and scientists have launched shifting devices that measure conditions in the upper mile of water but researchers still struggled to collect data from the deep ocean and to detect the long term trends underlying day to day variations in temperature now however scientists have developed a new technique that allows them to measure temperature changes across entire ocean basins. The idea dates back to the nineteen seventies when researchers first proposed using sound waves to study ocean warming because the speed of sound through water depends on the physical properties of that water which are related to temperature and lawfully if we will mobs ocean temperature by one degree this on the speed of change. It's it would be for meters pass. Kent and this is. This is very sensitive. Change when bo wu seismologist also at caltech who led the study that one degree he mentioned is a celsius degree researchers originally proposed using artificial sound sources but that notion got nixed because of concerns about the impacts on marine animals in the new study however woo kelly's and their colleagues show that they can use the sounds produced by earthquakes instead in an earthquake. Some vibrations bounced off the sea floor in. Turn into sound waves. That get picked up by seismometers. Underwater microphones the researchers. Looked the travel times of these sound waves for two thousand pairs of earthquakes. That occurred in the east indian ocean between two thousand and five and twenty sixteen. Each earthquake pair happened in the same place but at different times allowing the researchers to measure how much the sound waves sped up the analysis revealed that the waves traveled a few tenths of a second faster in more recent quakes than older ones a difference that translates to a warming trend zero point zero four degrees celsius per decade four. One hundredths of a degree may not sound like a lot. But it represents a huge amount of heat considering. It's the change in a body of water almost two thousand miles wide and several miles deep. The warming is also substantially higher than the rate reported in previous studies. Although kelly says not to put too much stock in those discrepancies. We don't know whether that is the general finding new curse Here in this in this region at this time or whether that is something we'll find another beach says while we just don't have the date is yet. the study is in the journal. Science kelly's and wu save this approach may even enable scientists to gauge historical temperature changes by studying data from much older earthquakes. In other words. You could say that the method is sound.