Virtually all changes in global atmospheric temperatures in the late 20th century were the result of nature rather than human activity, according to a new peer-reviewed study, one of whose authors predicted Friday was “sure to cause a stir.”
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De Freitas and Australian scientists John McLean and Bob Carter reported that at least 80 percent of climate variability tracked over the past half a century could be attributed to internal climate-system factors including the El Nino-Southern Oscillation (ENSO) Pacific warming phenomenon and its cooling twin, La Nina.

This left little room for human-caused factors like emissions of carbon dioxide (CO2) and other so-called greenhouse gases. Intermittent volcanic activity, producing significant cooling, was found to have been a factor.