Global ocean warming has been underestimated by as much as 58 percent in previous studies, reveals a latest research.
Dr Paul Durack, an Australian oceanographer from the U.S. Department of Energy's (DOE) Lawrence Livermore National Laboratory, suggests that the underestimation has been due to scarce historic temperature data of the Southern Ocean. The oceans in the southern hemisphere comprises about 60 percent of the total world's oceans. It includes Indian Ocean, South Atlantic, South Pacific and Southern oceans. Scientists have not sampled these oceans as much as they have sampled the oceans of the northern hemisphere.
Scientists from the U.S. National Aeronautics and Space Administration (NASA) and DOE made satellite observations, which included sea surface height changes alongside data of ocean temperatures accumulated from 1970 to 2004. The scientists compared the results of their examination with the current climate models.
Experts reveal that the height of the sea surface is a key global warming indicator. When oceans of the Earth gets warmer, the sea level also rise as result of ice melting on land.
Dr. Durack and his team reveals that their satellite observations found relative variation in the height of sea surface between the Southern and the Northern hemispheres was consistent when measured against climate models in place since 1993.
However, the warming estimation of the climate model in the top 700 meters of Earth's oceans are inconsistent with the data of ocean temperature recorded prior to 2004.
With the help of precise satellite data and an extensive suite of climate model simulations the current research was able to observe that the upper-ocean warming was underestimated by up to 58 percent. Dr. Durack also indicates that previous studies have pointed towards the underestimation of ocean warming but this is the first study, which found how much the underestimation was.
"It's likely that due to the poor observational coverage, we just haven't been able to say definitively what the long-term rate of Southern Hemisphere ocean warming has been," says Dr. Durack. "It's a really pressing problem - we're trying as hard as we can, as scientists, to provide the best information from the limited observations we have."
A separate study also suggests that the upper 2 kilometers of the ocean witnessed increased warming in between 2005 and 2014. However, the temperature below two kilometers has barely changed.
Dr. Durack's study has been published in the journal Nature Climate Change.
