A newly published study indicates that the recently claimed “pause” or “slowdown” in global warming is simply an artifact of inadequate sampling of arctic temperatures. Correction of this deficiency in data shows that warming has not paused.
Coverage bias in the HadCRUT4 temperature series and its impact on recent temperature trends
by Kevin Cowtan and Robert G. Way
A learned discussion of the paper and its implications can be seen at Real Climate:
Cowtan and Way apply their method to the HadCRUT4 data, which are state-of-the-art except for their treatment of data gaps. For 1997-2012 these data show a relatively small warming trend of only 0.05 °C per decade – which has often been misleadingly called a “warming pause”. The new IPCC report writes:
Due to natural variability, trends based on short records are very sensitive to the beginning and end dates and do not in general reflect long-term climate trends. As one example, the rate of warming over the past 15 years (1998–2012; 0.05 [–0.05 to +0.15] °C per decade), which begins with a strong El Niño, is smaller than the rate calculated since 1951 (1951–2012; 0.12 [0.08 to 0.14] °C per decade).
But after filling the data gaps this trend is 0.12 °C per decade and thus exactly equal to the long-term trend mentioned by the IPCC.
The corrected data (bold lines) are shown in the graph compared to the uncorrected ones (thin lines). The temperatures of the last three years have become a little warmer, the year 1998 a little cooler.
The authors write in their introduction:
While short term trends are generally treated with a suitable level of caution by specialists in the field, they feature significantly in the public discourse on climate change.
This is all too true. A media analysis has shown that at least in the U.S., about half of all reports about the new IPCC report mention the issue of a “warming pause”….
The public debate about the alleged “warming pause” was misguided from the outset, because far too much was read into a cherry-picked short-term trend. Now this debate has become completely baseless, because the trend of the last 15 or 16 years is nothing unusual – even despite the record El Niño year at the beginning of the period. It is still a quarter less than the warming trend since 1980, which is 0.16 °C per decade. But that’s not surprising when one starts with an extreme El Niño and ends with persistent La Niña conditions, and is also running through a particularly deep and prolonged solar minimum in the second half.
The physics and the math aren’t changing. The ice in our cold drink is melting. We can see it.
But we keep plunging towards catastrophe.