The “Pause” in Global Warming: Turning a Routine Fluctuation into a Problem for Science

Abstract

There has been much recent published research about a putative “pause” or “hiatus” in global warming. We show that there are frequent fluctuations in the rate of warming around a longer-term warming trend, and that there is no evidence that identifies the recent period as unique or particularly unusual. In confirmation, we show that the notion of a pause in warming is considered to be misleading in a blind expert test. Nonetheless, the most recent fluctuation about the longer-term trend has been regarded by many as an explanatory challenge that climate science must resolve. This departs from long-standing practice, insofar as scientists have long recognized that the climate fluctuates, that linear increases in CO2 do not produce linear trends in global warming, and that 15-yr (or shorter) periods are not diagnostic of long-term trends. We suggest that the repetition of the “warming has paused” message by contrarians was adopted by the scientific community in its problem-solving and answer-seeking role and has led to undue focus on, and mislabeling of, a recent fluctuation. We present an alternative framing that could have avoided inadvertently reinforcing a misleading claim.

The global warming hiatus has faded away: An analysis of 2014–2016 global surface air temperatures

“…Based on the results shown in Figures e–h and , the DM component was in a cooling phase during 2000–2010, which offset the long‐term warming trend and caused the warming hiatus (Huang et al , ). The “warming hiatus” is just a decadal climate fluctuation or perturbation, as illustrated in recent studies (Lewandowsky et al , ). Since 2013, the DM component has entered a warming phase; this is evident from the global, land, and ocean surface temperature time series.…”

Characterizing and attributing the warming trend in sea and land surface temperatures

“…Does it imply that the slowdown never really existed? Recent papers have analyzed unfiltered global temperature series and have concluded that the recent slowdown was either an artefact of the data or that it never really happened (Foster and Rahmstorf, 2011;Karl et al, 2015;Cahill et al, 2015;Lewandowsky et al, 2015Lewandowsky et al, , 2016. A large part of the body of research on this topic has concluded that the apparent hiatus could be produced by the effects of low-frequency natural variability represented by physical modes such as AMO, NAO and PDO (Li et al, 2013;Trenberth and Fasullo, 2013;Steinman et al, 2015;Guan et al, 2015).…”

Apparent limitations in the ability of CMIP5 climate models to simulate recent multi-decadal change in surface temperature: implications for global temperature projections

“…The behaviour of globally average surface temperatures over the period 1998 to 2012/2014 has attracted a great deal of attention, with questions being raised as to whether the observed values represented a serious hiatus (or pause) in global warming or whether they simply corresponded to a decadal-scale fluctuation associated with internal variability of the climate system (Lewandowsky et al 2015(Lewandowsky et al , 2016. The Intergovernmental Panel on Climate Change (IPCC 2013;Flato et al 2013) concluded that a reduction of the warming trend (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) was attributable, in roughly equal measure, to a cooling contribution from both internal climate variability, and external forcing comprising solar and volcanic activity.…”