The Oceans Warmed up Sharply in 2013: We're Going to Need a Bigger Graph

Because the oceans cover some 71% of the Earth's surface and are capable of retaining heat around a thousand times that of the atmosphere, the oceans are where most of the energy from global warming is going - 93.4% over recent decades. So greenhouse gases emitted by human industrial activity not only cause more heat to become trapped in the atmosphere, they also cause more of the sun's energy to accumulate in the oceans.

Long-term the oceans have been gaining heat at a rate equivalent to about 2 Hiroshima bombs per second, although this has increased over the last 16 or so years to around 4 per second. In 2013 ocean warming rapidly escalated, rising to a rate in excess of 12 Hiroshima bombs per second - over three times the recent trend. This doesn't necessarily mean we are entering a period of greatly accelerated ocean warming, as there is substantial year-to-year variation in heat uptake by the oceans. It does, however, once again dispel the persistent myth of a pause in global warming, because the Earth has actually continued to warm faster in the last 16 years than it did in the preceding 16 years.

As can be seen in Figure 1 below, the global oceans have warmed so quickly in 2013 that the National Oceanographic Data Center (NODC) is going to need a bigger graph.         


Figure 1 - Ocean Heat Content data  for the 0-2000 metre layer (based on Levitus [2012]) for the period 1957-2013. The orange band highlights the interval falsely labelled as a 'pause' in global warming. Further ocean warming will necessitate the vertical axis being extended. Image adapted from the National Oceanographic Data Center (NODC).

Posted by Rob Painting on Friday, 31 January, 2014

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