The National Oceanic and Atmospheric Administration has just released a report that looks at the various global temperature data sets and finds that they are now all "consistent" with man-made global warming. The chief cause is the emission of greenhouse gases such as carbon dioxide released from the burning of fossil fuels.
Global warming skeptics (and I was definitely one of them) have cited the findings of John Christy and Roy Spencer at the University of Alabama at Huntsville who have produced a temperature series based on satellite measurements since 1979. Throughout the 1980s and 1990s, the UAH data series saw little or no warming and its findings were bolstered by separate weather balloon data that also found little warming. In the past few years corrections made to the data sets have boosted average global temperatures in both.
NOAA's new report takes a look at all of the data sets and finds that they all point toward a trend of increasing average warmth:
Global-average temperature increased at a rate of about 0.12 degrees C per decade since 1958, and about 0.16 degrees C per decade since 1979. In the tropics, temperature increased at about 0.11 degrees C per decade since 1958, and about 0.13 degrees C per decade since 1979.
However, the question of how high temperatures are likely to go in the future is still open. Christy told the Washington Post that he has "a minimalist interpretation" of the report because Earth is not heating up rapidly at this point. And questions about what policies should be adopted, e.g., cutting emissions, fostering a technological revolution, adapting, or some combination, are now clearly on the table. The next couple of decades are going to be interesting and very contentious.