Rising Ocean Temperature: Is the Pacific Ocean Calling the Shots?

Key Points:

• Even though the ocean has warmed strongly, global 'surface' warming in the 21st century has been slower than previous decades.  One of the prime suspects for this has been an increase in trade winds which help to mix heat into the subsurface ocean - part of a natural oscillation known as the Interdecadal Pacific Oscillation (IPO).
• A recently published research paper, Chen & Tung (2014), claim that changes in the saltiness (salinity) of seawater in the North Atlantic is responsible for the decadal-scale variation in ocean heat uptake, rather than the IPO, as increased saltiness makes surface water denser and therefore facilitates the sinking of water transported poleward.
• Chen & Tung's  own analysis, however, shows that North Atlantic Ocean warming peaked in 2006 and has declined since that time whereas deep ocean warming, as a whole, has not.
• This new research affirms earlier work (Meehl et [2011] & Meehl et al [2013]) implicating the increased, albeit likely temporary, mixing of heat down into deeper ocean layers as a key contributor to the slower rate of surface warming in the 21st century.

Rising Ocean Temperature:  Is the Pacific Ocean Calling the Shots?