Sunday, February 23, 2014

Why the Global Warming Pause?

Sunrise over the Pacific from the International
Space Station.  Click for photo credit.
Many in the scientific community have been puzzled over the pause in global warming.

As a reminder, planetary temperatures have been rising steadily over the last century as a result of the increase in greenhouse gases.  Most are very familiar with the famous hockey stick curve that shows the association quite nicely.

However, over the last several years, the warming has slowed or stopped.  Note, this does not mean that we are back to normal.  Indeed, we are in a new normal of planetary atmospheric change.  Our temperatures have risen over 1 degree already in the last century and we have seen sea level changes that foretell trouble.  We have an atmospheric chemistry we have not had for hundreds of thousands of years.  Even though the warming has slowed or stopped.  We have not gone back to normal.

So what happened?

Researchers have been trying to puzzle out what happened to the heat that was created in the atmosphere and they think they found the answer.  The heat is stored in the Pacific Ocean.

The Pacific goes through a 20 year cycle of water exchange that shifts water from the surface to the subsurface and back again.  The heat is getting pushed down to great depths in the Pacific Ocean.

You might think that this is a good thing and we would not have anything to worry about.  Wrong.  The heat will be rereleased in 20 years when it is brought back to the surface.  We are about 10 years into the cycle and the Pacific has seen significant heating up over the last decade or so.  Read more about this here.

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