Others have looked to natural climate systems for explanations for answers to the 15-year pause in global warming.
A study by Dr. Roy Spencer from the University of Alabama, Huntsville found that about half the warming that occurred since the 1970s can be attributed to El Niño weather events, which had a warming effect on the planet.
The Pacific Ocean’s natural warming and cooling cycles last about 30 years, with La Niña cooling being dominant from the 1950s to the 1970s and El Niño warming events dominating late 1970s to the late 1990s. Spencer suggests that the world may be in a La Niña cooling period.
Read more: http://dailycaller.com/2013/12/13/study-earth-was-warmer-in-roman-medieval-times/#ixzz2nOtymIJN