I think that the idea of a pause in the global warming has been a red herring ever since it was suggested, and we have commented on this several times here on RC: On how data gaps in some regions (eg. the Arctic) may explain an underestimation of the recent warming. We have also explained how natural oscillations may give the impression of a faux pause. Now, when we know the the global mean temperature for 2016, it’s even more obvious.
Easterling and Wehner (2009) explained that it is not surprising to see some brief periods with an apparent decrease in a temperature record that increases in jumps and spurts, and Foster and Rahmstorf (2012) showed in a later paper how temperature data from the most important observations show consistent global warming trends when known short-term influences such as El Niño Southern oscillation (ENSO), volcanic aerosols and solar variability are accounted for.
A recent paper by Hausfather et al. (2017) adds little new to our understanding, although it confirms that there has not been a recent “hiatus” in the global warming. However, if there are doubts about a physical condition, then further scientific research is our best option for establishing the facts. This is exactly what this recent study did.
The latest findings confirm the results of Karl et al. 2015 from the National Oceanic Atmospheric Administration (NOAA), which Gavin described in a previous post here on RC. The NOAA analysis received unusual attention because of the harassment it drew from the chair of the US House Science Committee and the subpoena demand for emails.
Science is convincing because it builds on independent assessments, which either confirm or disagree with previous findings. A scientific consensus is established when many independent lines of evidence underpin the same conclusions.
It is important to realize that science is about universal truths, which means that you should get a consistent picture in a comprehensive analysis. The idea of a hiatus was indeed inconsistent with other indicators, such as the global sea level which continued to rise unabated (Watson et al, 2015). And there was no reason to think that changes in the cryosphere and precipitation had ceased either.
More than 70% of earth’s area is oceans, and sea surface temperatures (SSTs) carry a large weight in the global mean surface temperature estimates. Karl et al. (2015) reported a cold bias in recent SSTs due to changing observing network. This bias gave the false appearance of a slow-down in the warming of the oceans, and by taking into account artifacts from a change in the observing network, Karl et al found a more pronounced warming in the recent decade. Hausfather et al. (2017) studied these more closely, and their findings confirmed the NOAA analysis.
Rising levels of CO2 may not only result in a global mean surface warming, but it is also possible that it accelerates the turnaround of the hydrological cycle (Benestad, 2016). So even a hypothetical period could take place with a reduced warming rate, but it would be accompanied with an accelerated atmospheric vertical overturning.
- D.R. Easterling, and M.F. Wehner, "Is the climate warming or cooling?", Geophysical Research Letters, vol. 36, 2009. http://dx.doi.org/10.1029/2009GL037810
- G. Foster, and S. Rahmstorf, "Global temperature evolution 1979–2010", Environmental Research Letters, vol. 6, pp. 044022, 2011. http://dx.doi.org/10.1088/1748-9326/6/4/044022
- Z. Hausfather, K. Cowtan, D.C. Clarke, P. Jacobs, M. Richardson, and R. Rohde, "Assessing recent warming using instrumentally homogeneous sea surface temperature records", Science Advances, vol. 3, 2017. http://dx.doi.org/10.1126/sciadv.1601207
- T.R. Karl, A. Arguez, B. Huang, J.H. Lawrimore, J.R. McMahon, M.J. Menne, T.C. Peterson, R.S. Vose, and H. Zhang, "Possible artifacts of data biases in the recent global surface warming hiatus", Science, vol. 348, pp. 1469-1472, 2015. http://dx.doi.org/10.1126/science.aaa5632
- C.S. Watson, N.J. White, J.A. Church, M.A. King, R.J. Burgette, and B. Legresy, "Unabated global mean sea-level rise over the satellite altimeter era", Nature Climate Change, vol. 5, pp. 565-568, 2015. http://dx.doi.org/10.1038/nclimate2635
- R.E. Benestad, "A mental picture of the greenhouse effect", Theoretical and Applied Climatology, vol. 128, pp. 679-688, 2016. http://dx.doi.org/10.1007/s00704-016-1732-y