Ocean cooling linked to dip in global temperatures in 1970s

While exploring the redesign for Nature this news article (published online September 22) caught my eye: 

When the North Atlantic Caught a Chill - Surface cooling could have pushed down temperatures in the Northern Hemisphere 40 years ago."

"The sudden cooling event [of 0.3 °C ] that Thompson and his colleagues report¹ on page 444 of this issue [September 23] could help to solve a mystery: a prominent drop in the global mean surface temperature record around the same time. The ocean cooling, which may have resulted from a shift in currents, also offers a reminder of the North Atlantic's outsize role in climate."

Excellent background information is available in this text:
Atmosphere, ocean, and climate dynamics : an introductory text / John Marshall and R. Alan Plumb. Elsevier Academic Press, c2008.  Science Library QC880.4.A8 A877 2007  [plus 7 other copies in OhioLINK]