One of the great puzzles of climate science is the fact that global average temperature have been largely flat for the past 15 or more years. This hiatus in the rate of warming due to increasing greenhouse concentrations in the atmosphere was unpredicted by the computer climate models. Lots of scientific effort has gone into trying to explain (explain away?) the hiatus. The result has been numerous papers that variously blame ocean currents in the Pacific, the North Atlantic, or both; changes in water vapor in the stratosphere; and the lack of sunspot activity.
Basically all of the surface and satellite temperature records report that there has been a pause in the rise of global temperatures…until now. A new study published in Science jiggers the numbers for sea surface temperatures and finds, voilá, that the supposed hiatus disappears and that global temperatures have actually been going up the whole time. Phys.org reports the results:
"The new analysis suggests no discernible decrease in the rate of warming between the second half of the 20th century, a period marked by manmade warming, and the first fifteen years of the 21st century, a period dubbed a global warming 'hiatus,'" the report said.
The study uses "updated and corrected temperature observations taken at thousands of weather observing stations over land and as many commercial ships and buoys at sea," it said.
With that data, there is no evidence that temperatures in the 21st century have in fact plateaued.
"Instead, the rate of warming during the first fifteen years of the 21st century is at least as great as that in the last half of the 20th century, suggesting warming is continuing apace," said the study.
Very interesting to say the least. However, Phys.org notes that not everyone agrees with the new results:
Some experts hailed the Science article for using better quality data than the figures used to create the Intergovernmental Panel on Climate Change's 2013 report, which found some evidence of a pause in global warming in recent years.
But others, like Piers Forster, professor of climate change at the University of Leeds, pointed out that the IPCC report relies on numerous sets of data, not just NOAA's.
"Even with the corrections in this study, the observed warming has not been as large as predicted by models. Other global datasets, even when corrected for missing Arctic data, still show a decreased trend since 1998," he said.
"I still don't think this study will be the last word on this complex subject."
Interestingly, the folks who compile the satellite temperature record at the University of Alabama in Huntsville recently revised their global temperature trend data downward.
It could be that everyone else is wrong and the new study is right; but it could be also that it is an exercise in confirmation bias. Only time and more research will tell.