title: On the definition and identifiability of the alleged "hiatus" in global warming.
abstract: Recent public debate and the scientific literature have frequently cited a "pause" or "hiatus" in global warming. Yet, multiple sources of evidence show that climate change continues unabated, raising questions about the status of the "hiatus". To examine whether the notion of a "hiatus" is justified by the available data, we first document that there are multiple definitions of the "hiatus" in the literature, with its presumed onset spanning a decade. For each of these definitions we compare the associated temperature trend against trends of equivalent length in the entire record of modern global warming. The analysis shows that the "hiatus" trends are encompassed within the overall distribution of observed trends. We next assess the magnitude and significance of all possible trends up to 25 years duration looking backwards from each year over the past 30 years. At every year during the past 30 years, the immediately preceding warming trend was always significant when 17 years (or more) were included in the calculation, alleged "hiatus" periods notwithstanding. If current definitions of the "pause" used in the literature are applied to the historical record, then the climate system "paused" for more than 1/3 of the period during which temperatures rose 0.6 K.
authors.affiliation: School of Experimental Psychology and Cabot Institute University of Bristol, 12A Priory Road, Bristol, BS8 1TU, United Kingdom.
authors.forename: Stephan
authors.initials: S
authors.lastname: Lewandowsky
authors.affiliation: CSIRO Oceans and Atmosphere, Box 1538, Hobart, Tasmania 7001 Australia.
authors.forename: James S
authors.initials: JS
authors.lastname: Risbey
authors.affiliation: Department of the History of Science, Science Center 371 Harvard University, 1 Oxford Street, Cambridge, Massachusetts 02138, USA.
authors.forename: Naomi
authors.initials: N
authors.lastname: Oreskes