It has been claimed that the early-2000s global warming ‘slowdown’ or ‘hiatus’, characterized by a reduced rate of global surface warming, has been overstated, lacks sound scientific basis, or is unsupported by observations. The evidence presented in a new commentary in Nature Climate Change by Fyfe et al. contradicts these claims.
The new Fyfe et al. paper is mainly in response to Karl et al. and Lewandowsky et al., who made the following statements in their abstracts:
“These results do not support the notion of a ‘slowdown’ in the increase of global surface temperature” – Karl et al., 2015, Science
“there is no evidence that identifies the recent period as unique or particularly unusual” – Lewandowsky et al., 2016, BAMS
Firstly, climate scientists agree that global warming has not ‘stopped’ – global surface temperatures and ocean heat content have continued to increase, sea levels are still rising, and the planet is retaining ~0.5 days of the sun’s incoming energy per year.
I think there is also broad agreement that climate scientists have probably not chosen the right words (e.g. ‘hiatus’) to describe the temporary slowdown, especially when talking to the media and the public.
However, there has very clearly been a change in the rate of global surface warming. Figure 1 shows rolling 15-, 30- and 50-year trends computed for different surface and satellite global temperature datasets. There are clear fluctuations in the rate of global temperature change in the past. We also expect similar fluctuations in future – global temperatures will not increase smoothly or linearly.
Just focusing on the observations, the most recent observed 15-year trends are all positive, but lower than most previous similar trends in the past few decades. This is a clear demonstration that the rate of change has slowed since its peak.
The full post is here