Thursday, August 07, 2014

Global Warming Pause Puts 'Crisis' In Perspective

Much has been written and argued, from all sides in the global warming debate, about the meaning of the asserted 17-year pause in global warming. Is a 17-year pause significant? Is a pause even occurring? Does the pause signal a longer-term halt to global warming or even a long-term cooling trend? Would a resumption of global warming to pre-pause rates end the global warming debate? A look at recent temperatures and their appropriate context provides helpful meaning to the much-discussed global warming pause.
Satellite instruments began uniformly measuring temperatures throughout the Earth’s lower atmosphere in 1979. Climate scientists overseeing these NASA satellite instruments produced the chart below showing the following temperature trends:
  • a plateau of temperatures, with absolutely no warming, from 1979 through 1997
  • a large temperature spike in 1998
  • a return to the 1979-1997 mean in 1999-2000
  • a modest escalation of temperatures in 2001
  • an elevated plateau of essentially flat temperatures from 2002-2014
Source: drroyspencer.com
If we choose a starting point of mid-1998, the planet has cooled during the past 16 years. If we choose a starting point of late 1997 or early 1999, temperatures have been flat during the past 15 and 17 years. Examining the totality of the 35-year temperature record, we see approximately 1/3 of 1 degree Celsius warming during the period. Accordingly, global warming has occurred at a pace of approximately 1 degree Celsius per century over the duration of the satellite record.

No comments: