Normalcy

by Julie Walsh on January 18, 2008

I was having lunch a few months back with a friend who thinks that “maybe there is global warming” because when he was growing up in the 70’s it was colder than it is now. And it’s gotten a little warmer ever since then.

People tend to think of “normal” as the way it was at some point in their past, most often their childhood. So in the ‘70s, people started worrying about global cooling, partly because many people remember balmier temperatures when they were growing up.

The truth is, we don’t live in a climatically-static world. The Earth’s climate is a dynamic system:

Globally averaged temperature variations between 1850 and 2007 show the emergence from the "Little Ice Age" in the early 1900's, slight cooling from the 1940's to the 1970's, and then warming again since the 1970's. (HadCRUT3 temperature dataset from the UK Met Office and Univ. of E. Anglia)
Globally averaged temperature variations between 1850 and 2007.

Global average temperature reconstruction based upon 18 temperature proxies for the period 1 A.D. to 1995, combined with the thermometer-based dataset from the UK Met Office and University of East Anglia, covering the period 1850 to 2007. Note that for both datasets each data point represents a 30-year average. 2,000 years of global temperatures                      from temperature proxies and thermometer data.

 


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