NATURE NOT MAN RESPONSIBLE FOR RECENT GLOBAL WARMING
July 24, 2009
Three Australasian researchers have shown that natural forces are the dominant influence on climate, in a study just published in the highly-regarded Journal of Geophysical Research. According to this study little or none of the late 20th century global warming and cooling can be attributed to human activity.
The research, by Chris de Freitas, a climate scientist at the University of Auckland in New Zealand, John McLean (Melbourne) and Bob Carter (James Cook University), finds that the El Niño-Southern Oscillation (ENSO) is a key indicator of global atmospheric temperatures seven months later. As an additional influence, intermittent volcanic activity injects cooling aerosols into the atmosphere and produces significant cooling.
According to de Freitas:
- The surge in global temperatures since 1977 can be attributed to a 1976 climate shift in the Pacific Ocean that made warming El Niño conditions more likely than they were over the previous 30 years and cooling La Niña conditions less likely.
- Internal global climate-system variability accounts for at least 80 percent of the observed global climate variation over the past half-century.
- It may even be more if the period of influence of major volcanoes can be more clearly identified and the corresponding data excluded from the analysis.
Climate researchers have long been aware that ENSO events influence global temperature, for example causing a high temperature spike in 1998 and a subsequent fall as conditions moved to La Niña. It is also well known that volcanic activity has a cooling influence, and as is well documented by the effects of the 1991 Mount Pinatubo volcanic eruption.
Bob Carter, one of four scientists who has recently questioned the justification for the proposed Australian emissions trading scheme, says that this paper has significant consequences for public climate policy:
- The close relationship between ENSO and global temperature, as described in the paper, leaves little room for any warming driven by human carbon dioxide emissions.
- The available data indicate that future global temperatures will continue to change primarily in response to ENSO cycling, volcanic activity and solar changes.
"Our paper confirms what many scientists already know: which is that no scientific justification exists for emissions regulation, and that, irrespective of the severity of the cuts proposed, ETS (emission trading scheme) will exert no measurable effect on future climate," says Carter.
Source: Marc Morano, "Nature Not Man Responsible for Global Warming," Climate Depot, July 23, 2009; based upon: J.D. McLean, C.R. de Freitas and R.M. Carter, "Influence of the Southern Oscillation on Tropospheric Temperature," Journal of Geophysical Research, July 23, 2009.
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