The Oceans are Warming Faster than Previously Thought; Rate of Heat Build-up Accelerating

So we keep hearing this phrase in the sciences — faster than we thought. In the context of global warming, it’s not a phrase we want to hear. And when the world’s largest heat sink — the oceans — are warming up faster than we thought, that’s kind of a big deal.

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According to new research published today in Science Advances, the world’s oceans are warming up at an overall rate that is 13% faster than previously thought. Study authors used a new methodology to gain a more refined picture of overall ocean warming. And the results were unfortunately stark. For in addition to the oceans having gained more heat, the study also found that the rate of ocean warming is accelerating.

(Total ocean heat gain in the top 2000 meters as found in Improved estimates of ocean heat content from 1960 to 2015.)

This increased rate of warming is rather concerning — especially when you consider the fact that about 90 percent of the total extra heat absorbed by carbon dioxide and other greenhouse gasses produced primarily by fossil fuel burning ends up in the world’s oceans. For this reason, ocean heat gain is probably a better determiner of overall global warming than atmospheric heat gain. And, as a result, what we’re looking at is a world that’s surprising us with the rate at which it is responding to the insults of human fossil fuel emissions.

Serious Systemic Impacts From Ocean Warming

Of course, heat in the oceans produces numerous added impacts to the Earth System. As we’ve seen in Antarctica and Greenland, that heat gain has caused a number of the world’s largest ice shelves and glaciers to start melting from below — increasing concerns about the future rate of global sea level rise. The accelerating heat gain in the world’s oceans is absolutely the primary driver of the ongoing global coral bleaching event that has continued uninterrupted since 2014. More ocean heat means less oxygen — which increases the extent of ocean dead zones. And various sea creatures from starfish to mollusks to walruses to puffins have all seen habitat loss and/or loss of key food sources due to ongoing warming.

Extra ocean heat also both reduces the ability of the ocean to absorb CO2 even as it puts stress on various carbon stores — increasing the risk that a carbon feedback response from the Earth System will emerge to further worsen the rate of global warming.

(This year’s global coral bleaching event is starting to kick into high gear. Famous reefs such as the Great Barrier Reef are now threatened. But coral bleaching is just one of many harmful impacts that result from ocean warming. Image source: Coral Reef Watch.)

Finally, warmer oceans can help to push hydrological events such as instances of heavy rainfall and severe drought to greater extremes. A press release by the study’s authors noted:

…we know the oceans are much warmer now and they contain the memory of climate change. Higher sea surface temperatures are continually reinforced by the extra heat beneath the ocean surface. The oceans are affecting weather and climate through more intense rains. This process is a major reason why 2016 was the hottest year ever recorded at the Earth’s surface, beating out 2015 which was the previous record. Additionally 2015 was a year with record hurricanes, heat waves, droughts, and wild-fires around the world.

Conditions in Context — We Need Rapid Reductions in Greenhouse Gas Emissions Now

Ultimately what this accelerating and higher than expected ocean heat gain means is that we have less time. Less time to achieve a necessary reduction of emissions before various harmful and catastrophic effects from climate change get locked in. Less time to continue coddling a harmful fossil fuel industry, as the Trump Administration has determined to do. And less time to plan to help the populations of people that will inevitably be harmed by the warming that these vastly irresponsible political and economic powers have so far blocked us from preventing.

Links:

Improved Estimates of Ocean Heat Content From 1960 to 2015

Earth’s oceans are warming 13% faster than thought

Coral Reef Watch

Hat tip to Jeremy in Wales

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