In a series of papers published last year, BEST presented their statistical analysis of 1.6 billion temperature reports spanning the last 200 years, controlling for possible biases in the data that are often cited by skeptics as reasons to doubt the reality of global warming.
Their analysis indicated that global warming is real — that the average global land temperature has risen by 2.5 degrees Fahrenheit (1.4 degrees Celsius) since 1750, including 1.5 degrees F (0.9 degrees Celsius) in the past 50 years. The numbers closely agree with the findings of past studies by the National Oceanic and Atmospheric Administration (NOAA), NASA and others; but finally, they were rigorous enough to satisfy Muller.
Now, in a brand new study that probed the causes of that warming, the BEST team says it has cleared from blame the natural variations in Earth's climate that so often get implicated by skeptics. Muller and his colleagues implicate carbon dioxide emissions by humans as essentially the sole cause of global warming.
"The carbon dioxide curve gives a better match than anything else we've tried," he wrote Saturday (July 28) in a New York Times editorial. "Its magnitude is consistent with the calculated greenhouse effect — extra warming from trapped heat radiation. These facts don't prove causality and they shouldn't end skepticism, but they raise the bar: To be considered seriously, an alternative explanation must match the data at least as well as carbon dioxide does."
