If 2015 is the hottest year since whenever, what will that mean?

There is general acceptance among weather people that we are going to have an el Nino summer in our country. More generally, the el Nino is expected to persist until March/April. This will be good for California and Arizona, which are likely to get heavy rain, and have had drought conditions over the past few years dominated by la Nina conditions, meaning cooler and wetter for us in SE Australia.

Our summer is likely to be hot and dry. Since our dams are pretty full (Sydney’s water storage is at 98 per cent), this is unlikely to be a problem, at least for city-dwellers, unless the el Nino runs into a second year, which it might, though it has been about, in preparation, for much of this year. Lots of people, who should know better, are hoping for an el Nino, because it might signal the end of ‘the pause’ — the lack of significant warming for a decade or much more, according to which dataset you are looking at. Of course, since the el Nino is not connected to carbon dioxide accumulations, the outcome should be seen as yet another example of natural variations which affect temperature, rather than a sign that ‘global warming has started again!’

William Briggs, a fine statistician who writes good things about statistical inference on his website, has pondered on this one too. He starts with a puzzle.

There are two stories floating around about the state of the earth’s atmosphere. Both are believed true by government-funded scientists and the environmentally minded. The situation is curious because the stories don’t mesh. Yet, as I said, both are believed. Worse, neither is true. Story number one is that this year will be the hottest ever. And number two is that the reason it is not hot is because natural variation has masked or stalled man-caused global warming.

Two questions follow, for a reasonable person. How can people believe each of these two ‘divergent contentions’? And why are they false? Briggs answers the first by arguing that climatology has become a branch of politics …. any statement which supports globe warming is likely to be touted by government supporters, even mutually incompatible statements.

Briggs feels that he too is one of the people targeted by the climate scientists suggesting that the RICO Act be used against them. He is properly offended:

In other words, arguments put forward by independent scientists and organisations that do not support the government’s line cannot be considered science, but should instead by classified as criminal acts.

Why will 2015 not be the hottest ever, or on record? Briggs offers some evidence from the geologic record that will be familiar to anyone who has done some reading in this area — for example, this graph.

Yes, it’s a long, long record, and it’s all based on proxies (but then, thermometers provide  proxies too). On the face of it, the earth has generally been warmer than it is now. If you go back only a million or so years, the earth has been in  cold global temperatures (‘ice ages’) for most of that period, much colder than now. Cold is not good for life, which is why we use deep freezes to store food. And the relationship between temperature and carbon dioxide over the long haul is simply equivocal, as the next graph shows.

These graphs are usually dismissed or ignored, on the ground that we are really interested in the contemporary world. Or that there is uncertainty in the data. And there is. But there is uncertainty in all temperature data, wherever they come from. There are two principal sources of uncertainty, measurement error and statistical error, and virtually no one ever points them out on their graphs (these ones too). Briggs  comments:

The end result is to make temperature guesses appear smooth and uncomplicated, which is an illusion. That illusion makes it easier for (actually measured) temperatures in modern times to appear more variable. And that makes it easier to appear that we are hotter now, even if we’re not. 

The orthodox will object that these great shifts measured in millions of years don’t display ‘climate’, which is presently defined as the average of weather, and weather is what we have had for thirty years. These are simply conventional definitions, however, and have no ‘scientific’ status, other than their common use. If we go by the satellite temperature record, which starts in 1979, it would be relatively easy for there to be a record, if this year’s el Nino is like the one in 1998. Look at this graph, which shows both the satellite measurements:

But go up to the two top graphs, and you’ll see that this 36-year period is in geological terms a cool time, and such a record would mean nothing.

The ‘pause’. Briggs doesn’t like the term, because it implies a resumption of warming, from whatever cause. For him, el Ninos are an effect of climate, or an example, or an observation, not a cause of anything, even hot and dry here, which is simply part of el Nino — another observation. So to blame el Ninos for preventing the true outcome of more CO2 in the atmosphere is almost nutty. People who put forward this view use the absence of predicted increases as proof the increases were really there, but in masked or modified form! To them, the repeated, consistent and egregiously mistaken predictions made by climate models are true no matter what because [anthropogenic] global warming is true no matter what. 

This essay is easy to read and understand, and he is helpful on the use of parameters in global circulation models. I’ll let Professor Briggs have the last word:

The lesson to be learned from this is that the climate is never constant; it always has changed and always will. Stopping climate change is a human impossibility. 

Footnote: After I had written this piece I discovered a lengthy and useful essay on the quality of temperature data at http://wattsupwiththat.com/2015/09/24/summary-of-ghcn-adjustment-m odel-effects-on-temperature-data/

Along with the scientists wanting others who disagree with them to be investigated as though they were racketeers, and David Attenborough’s suggestion that we spend even more money making renewable energy affordable, comes a law professor seeking to have the International Court of Justice actually rule on climate change, so the dissidents will finally be quashed. It’s a strange world we live in.

Oh, and Associated Press has decided that from now on its staff won’t use the word ‘denier’ or its close relatives. They are now to refer to such people as ‘climate change doubters’, and those of the opposite persuasion as ‘climate change proponents’. I think I’ll continue with the ‘orthodox’. The real ‘deniers’ to me are those who think that the science of climate is settled.