Global Warming and Ocean Heating

With the help of  www.skepticalscience.com, we can put to rest a widespread misconception with respect to global climate change. Although warming of the global surface air temperature has slowed in the past decade (partly due to repeated La Nina events), the rate of global heat accumulation has not. The global heat accumulation (or the total heat content of the Earth) rather than the temperature of the lower atmosphere  is the  variable that  represents the overall response of the Earth to increased warming.  For the 1993 to 2003 period, atmospheric  heat content constituted only 2.3% of the total global heat budget whereas  over 93% of the global warming went into the oceans.   As can be seen from the figure, most of the ocean’s heat content resides in the top 700 meters  (2300 feet).

Change in total heat content of the Earth over past 5 decades. From Nuccittelli et al., 2012

Change in total heat content of the Earth over past 5 decades. From Nuccittelli et al., 2012

The remaining  fraction was apportioned between the deep ocean, continents,  glaciers and ice caps, Arctic sea ice, and the Antarctic and Greenland ice sheets. The deep ocean, although representing only a small fraction of the global energy budget is sometimes ignored in energy budget calculations because of the limited database, but doing so underestimates the global heat flux.

 The figure also shows that over the past 15 years, our planet has accumulated more heat than in the prior 15 years as would be expected in a global warming regime. The term global heating, not global temperature, is the valid  term to use when discussing the global energy balance.  Those who cite recent atmospheric temperatures  as evidence that  global  warming is not occurring or has stopped, are wrong.

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Nuccitelli, D,  R. Way,  R. Painting,  J. Church and J. Cook.  2012. Comment on Ocean heat content and Earth’s radiation imbalance. II. Relation to climate shifts.  http://www.skepticalscience.com/docs/Comment_on_DK12.pd

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