Satellite Data Shows No Global Warming For Nearly 19 Years
Scientists with the National Oceanic and Atmospheric Administration released a study Thursday claiming there’s no hiatus in global warming. But new satellite-derived temperature measurements show there’s been no global warming for 18 years and six months.
“For 222 months, since December 1996, there has been no global warming at all,” writes climate expert Lord Christopher Monckton, the third viscount Monckton of Brenchley
“This month’s [satellite] temperature – still unaffected by a slowly strengthening el Niño, which will eventually cause temporary warming – passes another six-month milestone, and establishes a new record length for the Pause: 18 years 6 months,” Monckton adds.
Monckton’s data comes as NOAA scientists release updated data purporting to show there’s actually been no hiatus in global warming. NOAA scientists made adjustments to temperature records to show more than twice as much warming as the old analysis at the global scale from 1998 to 2012.
“Newly corrected and updated global surface temperature data from NOAA’s [National Centers for Environmental Information] do not support the notion of a global warming ‘hiatus,’” wrote NOAA scientists in a new study.
The difference between Monckton’s data and NOAA’s data is that satellites measure the lowest few miles of the atmosphere, temperature measurements from government scientists rely on thousands of weather stations, buoys and ships across the world’s surface.
Both satellites and surface temperature readings, however, showed prolonged periods without statistically significant warming trends — 15 years for surface temperatures and more than 18 years for satellites.
Scientists have already pushed back against NOAA’s new study. The news site Mashable interviewed about a dozen climate scientists not involved in the study, and nearly all of them said “the study does not support the authors’ conclusion that the so-called warming pause never happened.”[See below]
“Instead, they said it simply proves that changing the start and end dates used for analyzing temperature trends has a big influence on those measurements, a fact that was already widely known,” Mashable reported.
“The main claim by the authors that they have uncovered a significant recent warming trend is dubious,” scientists with the libertarian Cato Institute wrote in an open letter on the NOAA study.
“The significance level they report on their findings (.10) is hardly normative, and the use of it should prompt members of the scientific community to question the reasoning behind the use of such a lax standard,” they wrote.
And there's this:
"Pushback from other researchers
Scientists who have investigated the warming hiatus or are otherwise involved in assessing climate change on various timescales said the study's key shortcoming is that it does what mainstream climate scientists have long criticized climate contrarians — often now referred to as "climate denialists" — of doing: cherry-picking start and end dates to arrive at a particular conclusion.
Gerald Meehl, a climate researcher at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, told Mashable in an email that while he finds the new study laudable for improving temperature measurements, there are flaws in how the researchers interpreted the data. For example, Meehl said there is still a lower warming trend from 1998 to 2012, compared to the previous base period of 1950 to 1999, "thus there is still a hiatus defined in that way."
Meehl said adding two years to the time period by including 2013 and 2014, which was a record-warm year, makes the warming trend appear to be 38% larger than previous studies that did not include them.
"My conclusion is that even with the new data adjustments, there still was a nominal hiatus period that lasted until 2013 with a lower rate of global warming than the warming rate of the last 50 years of the 20th century," he said, "and a factor of two slower warming than the previous 20 years from the 1970s to 1990s."
Lisa Goddard, director of the International Research Institute for Climate and Society (IRI) at Columbia University, told Mashable that the study does not support the conclusion that global warming didn't slow down for a relatively short time period.
"It is clear that Karl et al. have put a lot of careful work into updating these global products," Goddard said in an email.
"However, they go too far when they conclude that there was no decadal-scale slowdown in the rate of warming globally.
"However, they go too far when they conclude that there was no decadal-scale slowdown in the rate of warming globally. This argument seems to rely on choosing the right period — such as including the recent record-breaking 2014."
Another senior climate researcher, Kevin Trenberth of NCAR, said the hiatus depends on your definition of the term. To him, global warming never stopped, as climate skeptics argue, because most of the extra heat from manmade greenhouse gases (e.g. carbon dioxide) was redirected deep into the oceans from 1998 to 2012. However, surface temperatures did warm more slowly during this time.
"I think the article does emphasize that the kind of variation is now much more within the realm of expectations from natural variability, but it is a bit misleading in trying to say there is no hiatus," he said in an email.
In response to such criticisms, Karl said even the 1998-to-2012 period that climate skeptics have long focused on looks twice as warm with the revised data set — at 0.086 degrees Celsius of warming, compared to the previously calculated rate of just 0.039 degrees Celsius.
Using the new data, the 1998-to-2014 period shows warming that is "significantly positive," Karl said, of 0.106 degrees Celsius, up from 0.059 degrees Celsius using an older data set for the same period.
In light of the new data, other researchers recommend discounting the short-term fluctuations in favor of focusing on longterm warming.
Michael Mann, director of the Earth System Science Center at Pennsylvania State University, said the study helps drive home the point that "global warming continues unabated, as we continue to burn fossil fuels and warm the planet."
"Cherry-picking a warm start date like 1998, as contrarians are fond of doing in an attempt to downplay global warming, was never scientifically defensible to start with, and this article once again confirms that," Mann said in an email.
Why focus on a 15-year period anyway?
Regardless of whether the hiatus was really a hiatus, two things are clear. First, that slowdown is over anyway, given the record-warm 2014 and indications that 2015 may be a repeat of that. Second, focusing on relatively short timescales may be distracting from longterm global warming; however, it is important, since governments and businesses make decisions on shorter timescales. Decade-to-decade fluctuations in warming can affect everything from the productivity of agriculture in India to the likelihood that a U.N. climate treaty will be enacted, as a record-warm year can put pressure on politicians to act.
The IRI's Goddard, who has published extensively on the challenge of improving predictions of climate on decadal timescales, said she is puzzled as to why the new study discounts the importance of such short-term climate zigs and zags.
"All one has to do is to look at the time series to appreciate that the climate varies on all timescales, even when averaged over the whole globe. Global temperatures do NOT present a monotonic time series in which each year is warmer than the year before," she said. "I think that societally, it is important to realize that there will be periods of slowdown, as well as periods of acceleration."
Moving toward 'more sane' observing networks
One uncomfortable truth in climate science is that even at a time when we can wear computers on our wrists, we still don't have a truly global, extremely reliable network of climate-observing stations, which will prevent the need for additional data corrections in the future.
The new study reveals yet again that surface-temperature data has many flaws, according to Peter Thorne, a climate researcher at Maynooth University in Ireland. In an interview, Thorne said critics of climate science are incorrect in charging that global warming is an artifact of urban heat islands and other influences on thermometers; but at the same time, our approach to taking the Earth's temperature needs to be rethought.
Thorne said more investments should go toward establishing redundant, carefully calibrated temperature-observing networks where data is currently sparse, such as the Arctic, much of Africa and especially the oceans.
"The uncertainty in the marine records is far greater than in the land records," he said. "If we put enough good quality, traceable, redundant observations around the globe, we can make sense of all the other observations that aren’t so good."
"There is no need to bequeath onto researchers in 50 years time a similar mess."