YES

based on 10/16 datasets

Updated December 11, 2017

Data

datasetpause lengthgraph
UAHv6.0 TLT
Satellite
2017 Nov
24 years 9 months
0.118 ± 0.120 °C/decade
graph
RSSv3.3 TLT
Non-current
2017 Nov
24 years 7 months
0.118 ± 0.119 °C/decade
graph
RSSv3.3 TTT
Non-current
2017 Nov
23 years 10 months
0.119 ± 0.121 °C/decade
graph
RSSv4.0 TTT
Satellite
2017 Nov
21 years 4 months
0.149 ± 0.150 °C/decade
graph
RSSv4.0 TLT
Satellite
2017 Nov
21 years 3 months
0.158 ± 0.159 °C/decade
graph
UAHv5.6 TLT
Satellite
2017 Jul
20 years 6 months
0.158 ± 0.158 °C/decade
graph
Karl(2015)
Non-current
2014 Dec
18 years 1 months
0.111 ± 0.111 °C/decade
graph
Karl(2015) global
Non-current
2014 Dec
17 years 10 months
0.130 ± 0.130 °C/decade
graph
Berkeley
Land
2017 Jul
17 years 10 months
0.260 ± 0.261 °C/decade
graph
NOAA
Land
2017 Oct
12 years 8 months
0.305 ± 0.309 °C/decade
graph
HadSST3
Ocean
2017 Nov
< 10 yearsgraph
NOAA
Land/ocean
2017 Oct
< 10 yearsgraph
HadCRUT4
Land/ocean
2017 Oct
< 10 yearsgraph
HadCRUT4krig v2
Global
2017 Oct
< 10 yearsgraph
Berkeley
Global
2017 Oct
< 10 yearsgraph
GISTEMP
Global
2017 Oct
< 10 yearsgraph

Analysis courtesy of Dr Kevin Cowtan, York University

SCIENCE

Global Warming

Global warming refers to the phenomenon of increasing average surface temperatures of the Earth over the past one to two centuries.

Mann 2009

The "pause" or "hiatus" in global warming

Despite the continued increase in atmospheric greenhouse gas concentrations, the annual-mean global temperature has not risen in the twenty-first century1, 2, challenging the prevailing view that anthropogenic forcing causes climate warming.

Kosaka and Xie 2013

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 here contradicts these claims.

Fyfe et al. 2016

Scientific articles via Google Scholar

Time frames and relevance

Most scientific studies regarding the hiatus have considered time periods of a decade or longer. The science has looked for potential explanations for the "pause" and considered whether or not the discrepancy between expected versus observed warming might signal important shortcomings in the current understanding.

The simulations rule out (at the 95% level) zero trends for intervals of 15 yr or more, suggesting that an observed absence of warming of this duration is needed to create a discrepancy with the expected present-day warming rate.

Peterson et al. 2008

How long is the pause?

In order to claim there has been warming within a time period, we can't use just subjective judgement. Instead, the null hypothesis of only natural variability occurring has to be statistically rejected. This kind of hypothesis testing has been a routine part of climate science studies for decades.

In the inversion we employ an a priori null hypothesis for the GST history; that is, an initial estimate that there has been no climate change. This is a conservative hypothesis that is also fully independent of any extant models of climate change.

Huang et al. 2000

In statistics, a null hypothesis is what you expect to happen before you run an experiment. The idea is that if the results don't reject the null hypothesis, then you aren't finding anything new or surprising. The most common null hypothesis is the "no-change" or "no-difference" hypothesis.

Wikipedia

This website relies on the methodological choices of Foster and Rahmstorf (2011) and datasets (with some additions) selected by Dr Kevin Cowtan for the Skeptical Science temperature trend calculator to determine periods which do not reject the "no-change" null hypothesis.

The Skeptical Science temperature trend uncertainty calculator is a tool to allow temperature trends to be calculated with uncertainties, following the method in the methods section of Foster and Rahmstorf (2011) (Note: this is incidental to the main focus of that paper).
If the trend differs from some ‘null hypothesis’ by more than 2σ, then we say that the trend is statistically significant.

Skeptical Science

Despite the 2015-2016 El Niño (a natural warming spike, one of the strongest on record) most datasets do not indicate warming exceeding the 2σ error margin in the last 15 to 20 years.

Updates

14 March 2017: HadSST from MetOffice was added.

12 March 2017: Dr. Cowtan made some changes to the trend calculator:

  • The longest non-satellite dataset, Berkeley land-only, was removed.
  • The NOAA land-only dataset was removed.
  • HadCRUT4 was labeled "non-global", contradicting the data provider.
  • NOAA land/ocean was labeled "non-global", contradicting the data provider.
  • UAH 5.6 Satellite dataset was labeled "non-current" even though it is getting monthly updates.
  • UAH 6.0 was added.

In order to provide as complete and objective analysis as possible, we have now re-added the removed datasets on this site. We will provide updates directly from the original data sources (Berkeley Earth and NOAA). The sources are linked on the graph page.

Dr. Cowtan's interpretations regarding "non-globality" were replaced with the original data providers' (the CRU, NOAA) view. The apparent mistake about UAH being "non-current" was corrected.

Finally, the "HadCRUT4 krig v2" dataset was marked "unofficial". The provenance of this data is undocumented. It is apparently Dr. Cowtan's own analysis and not the official HadCRUT 4 data which is separately listed.

Validating the calculation

To reproduce these uncertainty calculations on Skeptical Science, hover the mouse pointer over the "pause length" value given on this site (e.g. "16 years"). You will see the starting point of the calculation as a decimal number, e.g. "start = 2001.083". Next, go to the Skeptical Science calculator, select the dataset, and enter that number as "Start date". Leave the "End date" box empty and click "Calculate". You can then check that the trend is within the error margin.