By using climate models and satellite data, scientists said that the Earth's ocean is warming faster than previously believed, a phenomenon that is crucial to understanding the impact of global warming.

Paul Durack, from the Lawrence Livermore National Laboratory (LLNL) in California, said that ocean warming is essential to understanding climate change as 90 percent of the world's heat is absorbed by the Earth's ocean.

Knowing the rate of ocean warming provides crucial information on how fast the atmosphere has heated up and how much sea levels will rise. The rising temperature of the Earth is linked with the rapid rise of sea levels and this poses unwanted implications such as the loss of animal habitats and people's homes, flooding and destructive erosions.

In a study published in the journal Nature Climate Change on Oct.5, Durack and colleagues found that the warming of the oceans in the northern and southern hemispheres between 1970 and 2004 has been underestimated.

Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) researcher Wenju Cai said that the bias could be attributed to few direct measurements taken in the south between 1970 and 2003. It was not until 2004 when Argo, a system of 3,600 automated profiling floats that provides real-time data for use in studies of the climate and the ocean, has been used to measure ocean temperatures worldwide.

"Using satellite altimetry observations and a large suite of climate models, we conclude that observed estimates of 0-700 dbar global ocean warming since 1970 are likely biased low," the researchers wrote. "This underestimation is attributed to poor sampling of the Southern Hemisphere, and limitations of the analysis methods that conservatively estimate temperature changes in data-sparse regions."

The upper level of the Earth's ocean had been warming at 24 to 58 percent faster than previously estimated and this means that the oceans absorb up to 58 percent more energy than previously estimated.

"Prior to 2004, research has been very limited by the poor measurement coverage," Durack said. "By using satellite data, along with a large suite of climate model simulations, our results suggest that global ocean warming has been underestimated by 24 to 58 percent. The conclusion that warming has been underestimated agrees with previous studies"

A second study which was also published in the Oct. 5 issue of the Nature Climate Change backed up the results of Durack's study. Felix Landerer of NASA's Jet Propulsion Laboratory said that the study, which looked at deep ocean warning using Argo, has found that the ocean above 2,000 meters is marked by continuing warming since 2005.

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