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El Niño and the record years 1998 and 2016

Filed under: — stefan @ 4 November 2017

2017 is set to be one of warmest years on record. Gavin has been making regular forecasts of where 2017 will end up, and it is now set to be #2 or #3 in the list of hottest years:

In either case it will be the warmest year on record that was not boosted by El Niño. I’ve been asked several times whether that is surprising. After all, the El Niño event, which pushed up the 2016 temperature, is well behind us. El Niño conditions prevailed in the tropical Pacific from October 2014 throughout 2015 and in the first half of 2016, giving way to a cold La Niña event in the latter half of 2016. (Note that global temperature lags El Niño variations by several months so this La Niña should have cooled 2017.) More »

The climate has always changed. What do you conclude?

Filed under: — stefan @ 20 July 2017

Probably everyone has heard this argument, presented as objection against the findings of climate scientists on global warming: “The climate has always changed!” And it is true: climate has changed even before humans began to burn fossil fuels. So what can we conclude from that?

A quick quiz

Do you conclude…

(1) that humans cannot change the climate?

(2) that we do not know whether humans are to blame for global warming?

(3) that global warming will not have any severe consequences?

(4) that we cannot stop global warming? More »

Why global emissions must peak by 2020

Filed under: — stefan @ 2 June 2017

(by Stefan Rahmstorf and Anders Levermann)

In the landmark Paris Climate Agreement, the world’s nations have committed to “holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 °C above pre-industrial levels”. This goal is deemed necessary to avoid incalculable risks to humanity, and it is feasible – but realistically only if global emissions peak by the year 2020 at the latest.

Let us first address the importance of remaining well below 2°C of global warming, and as close to 1.5°C as possible. The World Meteorological Organization climate report[i] for the past year has highlighted that global temperature and sea levels keep rising, reaching record highs once again in 2016. Global sea ice cover reached a record low, and mountain glaciers and the huge ice sheets in Greenland and Antarctica are on a trajectory of accelerating mass loss. More and more people are suffering from increasing and often unprecedented extreme weather events[ii], both in terms of casualties and financial losses. This is the situation after about 1°C global warming since the late 19th Century. More »

Fake news, hacked mail, alternative facts – that’s old hat for climate scientists

Distortion? False information? Conspiracy theories? Hacked email? Climate scientists have known all this for decades. What can be learned from their rich experience with climate propaganda.

The world is slowly waking up. “Post-truth” was declared the word of the year 2016 by the Oxford Dictionaries. Finally, people start to widely appreciate how dangerous the epidemic of fake news is for democracy.

Stir up hate, destroy discourse, make insane claims until no one can distinguish the most bizarre absurdity from the truth any more.

Thus the Austrian author Robert Misik aptly describes the strategy of right-wing populists.

Some call it “alternative facts”. (Those are the convenient alternative to true facts.) Let’s simply call it propaganda. More »

There was no pause

Filed under: — rasmus @ 22 January 2017

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.

More »


  1. D.R. Easterling, and M.F. Wehner, "Is the climate warming or cooling?", Geophysical Research Letters, vol. 36, 2009.
  2. G. Foster, and S. Rahmstorf, "Global temperature evolution 1979–2010", Environmental Research Letters, vol. 6, pp. 044022, 2011.
  3. 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, pp. e1601207, 2017.
  4. 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.