Global Warming "Hiatus" Never Happened: New Study
A study published yesterday in the journal Science refutes the much-publicized idea that there has been a recent slowdown or “hiatus” in the rate of
A team of scientists from the National Oceanic and Atmospheric Administration’s (NOAA’s) National Centers for Environmental Information (NCEI) and LMI used the latest global temperature data and improved calculation methods to reach this conclusion.
“Adding in the last two years of global surface temperature data and other improvements in the quality of the observed record provide evidence that contradict the notion of a hiatus in recent global warming trends,” said lead author Thomas R. Karl, director of NOAA’s NCEI and chair of USGCRP’s steering body. “Our new analysis suggests that the apparent hiatus may have been largely the result of limitations in past datasets.”
The “hiatus” idea gained prominence with the release of the Intergovernmental Panel on Climate Change’s (IPCC’s) Fifth Assessment Report, which found that the rate of warming from 1998 to 2012 was markedly lower than from 1951 to 2012. However, since the release of the IPCC report, NOAA scientists have made significant improvements in the calculation of trends and in the quality of temperature datasets. One of the most substantial improvements is a correction for sea surface temperatures that accounts for the difference between data collected from ships (the predominant method before the mid-1970s) and buoys (a more accurate, increasingly common approach).
New analyses demonstrate that incomplete spatial coverage also led to underestimates of the true global temperature change. The integration of dozens of datasets has improved spatial coverage for areas like the Arctic, where temperatures have been rapidly increasing in recent decades. Lastly, the incorporation of additional years of data, 2013 and 2014—with 2014 being the warmest year on record—has had a notable impact on the overall temperature trend since 1998.
Over the full period of record from 1880 to present, the newly calculated warming trend is not substantially different than reported previously (0.68°C per century [new] versus 0.65°C per century [old])—reinforcing that the new corrections mainly affect recent decades.
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