Nowadays, oceans across the globe absorb twice as much heat as in 1997. More than ninety percent of all the heat energy – which comes from global warming – is absorbed by the seas, according to a new study.
Scientists have observed that the heat content in oceans has risen in recent years. For the new study – published Monday (Jan. 18) in the journal Nature Climate Change – the researchers used high-tech modern underwater monitors, ocean-observing data (that goes back to the 1870s) and computer models, to figure out how much man-made heat has been absorbed by the oceans over the past 150 years.
The results showed that from 1865 to 1997, the oceans absorbed about 150 zettajoules of energy, and in the next eighteen years they absorbed another 150 zettajoules, according to the researchers.
For instance, if an atomic bomb (the size of “Little Boy” – Hiroshima) were to explode every second for a year, it would generate two zettajoules. That means that since 1997, the oceans have absorbed heat energy equivalent to “Little Boy”-like atomic bombs that would have exploded each second for about 75 years straight.
Paul Durack, co-author of the study and an oceanographer at the Lawrence Livermore National Lab in California, said that the changes that took place after 1997 are incredibly big. Although the overall numbers are rough – because of some decades when data was not available – they are still reliable, Durack stated.
The oceans trapped most of the heat in the upper 2,300 feet (about seven hundred metres). However each year, more heart energy is absorbed by deeper oceans as well, according to the researchers.
Peter Gleckler, lead author of the study and a climate scientist at Lawrence Livermore National Lab, stated that it is not necessarily the high numbers that are bothersome, but rather the speed at which they are increasing. The amount of trapped energy is accelerating quickly, he added.
As oceans get warmer, they can absorb less heat, which means that more heat remains on land surface an in the air, Dr. Chris Forest, co-author of the study and an Associate Professor of Climate Dynamics at the College of Earth and Mineral Sciences at Pennsylvania State University, said.
Jane Lubchenco, professor of marine sciences at Oregon State University and the former chief of the National Oceanic and Atmospheric Administration, said that the new finding shows that there may be serious consequences for marine life in years to come.
Jeff Severinghaus, a professor of geosciences in the Geosciences Research Division at the Scripps Institute of Oceanography, University of California, San Diego, noted that the study provides evidence that humans are dramatically heating the Earth.
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