A new study examining explanations for the 10- to 15-year “hiatus” in global warming has scientists “more confident than ever that human influence is dominant in long-term warming.” But climate skeptics are already firing back at the claims.
“In a time coinciding with high-level political negotiations on preventing climate change, skeptical media and politicians were using the apparent lack of warming to downplay the importance of climate change,” researchers with the Institute for Atmospheric and Climate Science (IACS) in Switzerland wrote in a study published Thursday in the journal Nature.
“A few years of additional data are unlikely to overturn the vast body of evidence that supports anthropogenic climate change,” reads the study, adding the recent El Nino and new data have them “more confident than ever that human influence is dominant” in global warming.
IACS’s study looked at different explanations for the “hiatus” in global warming, which the study defined as the 10 or 15 years after 1998, ultimately to put to rest arguments by skeptics the lack of warming during this time cut into theories of catastrophic warming.
“I think it does a really good job at tying a bow on the last five years or so of hiatus arguments,” Penn State University climate scientist Michael Mann told The Los Angeles Times.
But skeptics are already firing back at IACS’s work.
Dr. David Whitehouse with the Global Warming Policy Foundation reminded IACS the “hiatus” only ended because of a strong El Nino — a naturally-occurring weather event.
“The pause ended not because of gradual global warming but because of a natural weather event whose temporary increased rate of global warming was far too large to be anthropogenic,” Whitehouse wrote.
“One could be a little sarcastic in saying why would Nature devote seven of its desirable pages to an event that some vehemently say never existed and maintain its existence has been disproved long ago,” Whitehouse wrote. “Now, however, as the El Nino spike of the past few years levels off, analyzing the ‘pause’ seems to be coming back into fashion.”
The “hiatus” in warming confounded scientists for years, sparking a fierce debate over its causes or if it even existed. Tom Karl, a former National Oceanic and Atmospheric Administration scientists claimed to debunk the “hiatus” by adjusting buoy temperatures upward, creating more warming.
Some scientists saw Karl’s study as the final blow in the debate, but subsequent studies continued to argue for the existence of a “hiatus” being caused by natural factors.
Based on Karl’s data and increased warming in recent years, IACS researchers say the lack of warming from 1998 onward doesn’t diminish their confidence in long-term predictions made by climate models.
“In fact, it increases the confidence in the dominant role of humans in long-term warming,” reads the study.
IACS researchers removed natural factors, like El Nino events, aerosols and solar forcing, they found “the anthropogenically forced global warming signal has not decreased substantially.”
“When we take these into consideration, what we are left with from the apparent hiatus is not inconsistent with the understanding of human influence on global climate,” reads the IACS’s study.
“Then, as now, the deep ocean was proposed to store the heat,” the study found, adding “that this would be only temporary, although other factors such as aerosol forcing probably played a part in the halted warming.”
“A decade ago it was held that the anthropogenic signal of global warming was strong,” Whitehouse wrote. “Only when surface temperatures did not increase by the 0.3°C per decade most climate models had predicted that qualifications were made. Natural decadal variability was used to explain the lack of temperature rise and it resulted in a gradual change of view.”
“Whether the pause will return after the recent El Nino and its aftermath settles down remains to be seen,” Whitehouse wrote. “From its skeptical beginnings the pause has become the major controversy and debating point in climate science.”