A new paper written by scientists from six nations says that the slowdown in global temperatures in the early 20th century means that global warming will take longer than the IPCC predicted.
It has resulted in such headlines as that in the Times; We were wrong — worst effects of climate change can be avoided, say experts.
This is bound to infuriate some who maintain that there is no evidence that the slowdown in surface temperatures ever existed – an increasingly difficult stance to justify.
The study is published in the journal Nature Geoscience by a team of scientists led by Richard Millar of the University of Oxford. It has recalculated the carbon budget for limiting the Earth’s warming to 1.5 degrees Celsius above temperatures seen in the late 19th century. It had been widely assumed that this stringent target would prove unachievable, but the new study would appear to give us much more time to act if we want to stay below it.
It says that the world has warmed more slowly than has been forecast by computer models, and that the IPCC had overstated the impact of emissions. One of the authors, Professor Michael Grubb of University College London, admitted past predictions were wrong, and that he had changed his mind about the timescales involved in man-made climate change.
Some have responded to this paper by saying that the computer models were developed a decade or so ago and that they are bound to be looking a little inaccurate a decade later. So much is obvious. But it is far cry from the message by some strident climate scientists who maintain that the models accurately portray the real world — even when the evidence has been strong and growing that they do not. To have the discrepancy between climate model predictions and reality acknowledged in Nature Geoscience is good. It has already resulted in a substantial debate about this most fundamental approach to assessing the impact of man-made climate change, demonstrating once again that ‘the science’ is definitely not settled.
While one group of scientists argue that we have more time, another think we have not.
Weather Not Climate
The news release just issued by the Met Office; “A Pacific flip triggers the end of the recent slowdown,” is one of the most misleading releases I have ever read. It is curiously timed as much of the data for 2017 is obviously not in yet. Mind you, the Met Office has a habit of jumping the gun on temperature data — almost every year — with varying degrees of accuracy, and a habit to predict warmer temperatures than observed.
It says that a new analysis of 15-year running means of global surface temperature reveals that the slowdown in global warming seen between 1999 – 2014 is over thanks to three years of record temperatures. The end of this period was marked by globally high temperatures induced by an intense El Nino.
Must we say once again that using such a strong El Nino – a weather event – to calculate long-term climate trends is comparing apples and oranges? The HadCRUT4 global surface temperature database is flat between 2002 and 2014, a trend bound to be increased by the presence of high temperatures due to weather at the end of the database.
The Met Office has also offered yet another explanation for the slowdown. It is, it claims, due to temperature cycles in the Pacific which went into a cold phase in the 1990s and is now starting a warm phase. Professor Adam Scaife, the head of monthly to decadal prediction at the Met Office Hadley Centre, said: “The end of the recent slowdown in global warming is due to a flip in Pacific sea-surface temperatures. This was due to a change in the Pacific Decadal Oscillation which entered its positive phase, warming the tropics, the west coast of North America and the globe overall.”
However, what the Met Office fails to mention is that we may also be facing a shift in Atlantic temperatures to a cool phase, the so-called Atlantic Multidecadal Oscillation (AMO). In 1995, after a relatively quiet period in the Atlantic, the AMO flipped to the warm phase. In in a few years we are likely to see it flip back to its cool phase again, with its concomitant effect on global temperatures.
Nobody has any real idea what global surface temperatures will do in the near future. There are strong indications that the globe has been cooling. It could be that declining temperatures will revert to what they were before the 2015/16 El Nino event, bringing with it the return of the slowdown.
In short, assumptions made about important details of climate science that were accepted a decade ago are becoming increasingly frayed. Let us hope that a new era of scientific reality will replace the far-to-simple messages previously proclaimed to the public.