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Where’s the Heat? Check the Oceans

By Climate Central

The rate of atmospheric warming has been slower in past 15 years than the previous 30 — even as we’ve continued to pump greenhouse gases into the atmosphere. It is tempting to think that everything we’ve learned about greenhouse gases since 1857 is wrong, but it is not.

We tend to focus on land surface temperatures, because that’s where we live. However, it is critical to remember the climate system includes the oceans in addition to the atmosphere. And as it turns out, a tremendous amount of heat energy (that appears to be missing) has been absorbed by the sea. As the graphic above, based on the IPCC Fifth Assessment, illustrates, the amount of heat energy that has gone into the oceans since the warming began is phenomenal.


  • The annual energy absorbed by the upper global ocean is 43 times the amount of energy consumed by the U.S. in 2012 (the last year in which data is available).
  • The amount of energy on the chart is shown in a unit called zettajoules. A zettajoule is enough energy to power 25 billion average American homes for a year.

Additionally, we see more direct effects of CO2 on the oceans. When carbon dioxide mixes with the water, chemical reactions in the water (generally known as ocean acidification) consume carbonate ions, which can cripple the ability of corals and other creatures to form shells and critical exoskeletons. The oceans are now measurably more acidic than they were before human CO2 emissions first ramped up, and the acidity continues to worsen.

But the ocean’s capacity for storing heat is not unlimited. The warmer ocean leads to more evaporation, meaning more energy available to drive weather patterns, and very likely, more intense rainfall. As emissions continue, every expectation is that global temperatures will start rising more rapidly again in the coming years, and the “pause” will quickly be forgotten.

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