SCIENCE

The Global Warming Hiatus Was Just A Recording Glitch

Jun 04, 2015 at 2:06 PM ET

The Global Warming Hiatus is a myth, according to a new study published in the journal Science. “The rate of temperature increase over the past 15 years is virtually identical to what we’ve seen over the last half of the 20th century,” says Thomas R. Karl, director of the National Oceanic and Atmospheric Administration’s National Climatic Data Center and lead author on the study.

“That’s not much of a slow-down.”

Climate deniers loved the notion of a pause in global warming, and expert climate scientists (including members of the UN’s Intergovernmental Panel on Climate Change) were often at a loss. Sure, whether or not the planet was actually warming was never up for grabs, but the best data still suggested a pause or plateau in the rate of climate change. Since the 1950s, average global temperatures had risen regularly at a rate of about 0.2 degrees Fahrenheit per decade. But in the past 15 years, that figure dropped to roughly 0.12 degrees. Climate change was still happening, but it appeared to be slowing down.

But now, new data from NOAA shows that this global warming hiatus was an illusion. Researchers suspected that temperature observation data (often taken at sea, via instruments strapped to enormous buoys and commercial ships) might have been been biased, since data collection methods change often.

Modern commercial ships have largely shifted from the antiquated practice of measuring sea temperature via buckets flung off the side of the ship, to more modern engine intake thermometers. However, many ships still use buckets, and that introduces error into the temperature calculations (especially if the bucket material insulates the water). Meanwhile, weather buoys are increasingly filling in the data gaps left behind by commercial ships, but studies have shown that buoy data is almost always colder than ship data.

Based on this new information, several mathematical changes needed to be made. And when the dust settled, our global warming trends were sitting just where we’d left them in 1999.

Even the new, robust data suggest that there have been temporary lulls in the rate of climate change. Between 2001 and 2008, for instance, there’s clearly a bit of a drop off. But the overall trends are even more disturbing than we once thought—and to publish a chart more disturbing than the most recent IPCC report is a challenge. “From 1880 to 2014 there certainly are short periods when temperatures warm more rapidly or not as rapidly,” Karl says. “But looking at the longer picture, from 2000 to 2015, you indeed see a warming rate comparable to the longer term trends of the late 20th century.”

Unfortunately, this bit of mathematical tidying-up won’t end the climate debate. Climate deniers will likely spin this study into more fodder for their claim that, as long as the science is changing so often, we should hold off on major climate legislation. But Karl points out that changing theories and modifying calculations based on new data is precisely what science is all about. “We think the data we have today is pretty valuable and better than what we had just a few years ago,” Karl says. “Science is only as good as the data we have to work on.”