A recent study concluded there is no substantial evidence for a global warming "pause," or "hiatus" as has been suggested in the past.
A team of researchers reviewed 40 peer-reviewed scientific articles published between 2009 and 2014 that addressed the perceived "hiatus," and found there was no consistent data on when this hiatus began or how long it lasted, the University of Bristol reported.
"Our study raises the question: why has so much research been framed around the concept of a 'hiatus' when it does not exist? The notion of a 'pause' or 'hiatus' demonstrably originated outside the scientific community, and it likely found entry into the scientific discourse because of the constant challenge by contrarian voices that are known to affect scientific communication and conduct," said professor Stephan Lewandowsky of Bristol's School of Experimental Psychology and the Cabot Institute.
The researchers compared the distribution of decadal warming trends during the hiatus as described in the scientific papers with other trends of equivalent length in the entire record of modern global warming. The comparison showed that the definition of hiatus as defined in the papers did not line up with other trends. The findings also showed that if a study only used a small sample of data, a "hiatus" will almost always be perceived. This is because small sample sizes generally have "insufficient statistical power for the detection of trends," according to the researchers.
"Scientists may argue that when they use the terms 'pause' or 'hiatus' they know -- and their colleagues understand -- that they do not mean to imply global warming has stopped," Lewandowsky said. "But while scientists might tacitly understand that global warming continues notwithstanding the alleged 'hiatus', or they may intend the 'pause' to refer to differences between observed temperatures and expectations from theory or models, the public is not privy to that tacit understanding."
The researchers concluded that the scientific community should avoid the discussion of the concept of a global warming hiatus altogether unless conclusive evidence presents itself.
"Scientists should avoid the use of 'pause' or hiatus' when referring to fluctuations of global mean surface temperature around the longer-term warming trend. There is no evidence for a pause in global warming," Lewandowsky said.
The findings were published in a recent edition of the journal Scientific Reports.