Oceans absorbed heat equal to 2 bn times a Hiroshima bomb since 1997

  • Vignesh Radhakrishnan, Hindustan Times, New Delhi
  • Updated: Jan 26, 2016 13:12 IST
This file photo taken on October 06, 2014 shows heat radiating from the Pacific Ocean as imaged by the NASA’s Clouds and the Earth's Radiant Energy System instrument on the Terra satellite. (Nasa via AFP File Photo)

Oceans around the world have absorbed man-made heat energy to the tune of two billion Hiroshima-style atomic bombs in the last 18 years, a study released last week claimed.

The oceans absorbed approximately 150 zettajoules of energy from 1865 to 1997 and then absorbed about another 150 in the next 18 years, Nature Climate Change journal said in its study.

How much is a zettajoule?

“A zettajoule is 1 x 10 to the 21st power – so a very large number,” co-author of the paper Paul J Durack, an oceanographer at the Lawrence Livermore National Lab in California, told Hindustan Times.

According to Associated Press, an explosion of one Hiroshima-style atomic bomb every second for a year (which is 31,53,6000 bomb explosions) would release just 2 zettajoules of heat energy.

So from 1865 to 1997, in the pre-industrial era, our oceans absorbed man-made heat energy equivalent to 2,36,52,00,000 Hiroshima-style atomic bombs (31,53,6000 *150/2). And since 1997, in the post-industrial era, the heat energy absorption doubled with the oceans taking in heat energy equivalent to another set of 2,36,52,00,000 bombs.

“These numbers are approximately accurate and are consistent with the previously published work of the IPCC 2013 5th assessment report,” Durack said.

This image provided by Lawrence Livermore National Laboratory shows Pacific and Atlantic meridional sections showing upper-ocean warming for the past six decades (1955-2011). Red colours indicate a warming anomaly and blue colours indicate a cooling anomaly. The amount of global-warming triggered heat energy absorbed by the seas has doubled since 1997, a new study showed. (AP Photo)

Cause and effects

When asked about the reason behind such a doubling in the last 18 years, Durack squarely blamed it on careless human nature which led to an increase of greenhouse gases in the atmosphere, primarily CO2.

“The atmospheric composition changes are affecting the global temperatures. Many independent studies have confirmed these human-caused changes to many aspects of the climate system, from the atmospheric temperatures, to the ocean and many other aspects.”

“Previous work has shown that the spatial patterns and changes that we’re seeing in the earth climate system are a response to human-caused changes. The strong temperature increases that our new study has uncovered paints a clear picture of continuing ocean warming, and if we are to extrapolate into the future following the rates of change these show large increases will continue,” Durack said when asked about the effects we are facing because of the voluminous heat energy consumed by the oceans.

Is the data accurate?

Even though the numbers appear to be enormous, Durack is confident of his calculations.

“The oceanographic research community has been measuring the global ocean for many centuries, with constant changes to the technology employed to measure the ocean properties and continual improvements in the accuracy of the measurements,” he said.

“These data are the best that we have, and when the older data is compared and contrasted to the latest measurements from new high precision observations they check out well.”

(With AP inputs)

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