Global warming trend began two hundred years ago

A study of lichens in the French Alps adds to a growing body of evidence that contradicts the notion that 20th century warming is either CO2-induced or unprecedented.

According to two researchers, high-altitude avalanche activity during the Little Ice Age (LIA) reached its greatest maximum in about A.D. 1830. The researchers also report that most French Alpine glaciers have decreased since A.D. 1850. The mass balance of these glaciers is directly correlated with summer temperature and spring precipitation, say scientists.

Their findings suggest that the beginning of the end of LIA started somewhere in the early- to mid-1800s, in contrast to around 1910 as proposed by climate alarmists.

From these findings, the researchers conclude that:

  • Half of the warming experienced by the earth in recovering from what was likely the coldest part of the LIA occurred well before the 20th century.

  • An even greater part of the total warming occurred before the air's CO2 concentration began increasing in earnest, estimated to have happened in 1930.

  • Most of the warming of the past nearly two centuries must therefore owe its existence to something other than rising atmospheric CO2 concentrations.

    This timeline for the demise of LIA supports the conclusions of earlier work based on temperature data gathered on Mount Logan in Canada, as well as deep soil temperatures and deep ocean temperatures.

    Source: Keith Sherwood and Craig Idso, Avalanches of the French Alps, Centre for the Study of Carbon Dioxide and Global Change, July 28, 2004.

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    For more on Global Warming: Science

    FMF Policy Bulletin/28 September 2004
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