The Guardian’s Verdict: Objection, M’Lud!

  • Date: 10/01/13
  • Dr David Whitehouse

I always find it rather worrying when a journalist arrives at a verdict. An assessment or an analysis perhaps, but a verdict sounds too dogmatic, to judicial for me, and a little too self-important. It is especially dangerous in science and in a field as contentious as climate change where to many opinions, facts and analysis are interchangeable. Where some believe only a qualified few are allowed to hold opinions and others never tell the truth. Scientific truths are often provisional, but when he faced the Inquisition, Galileo, armed with data and a hypothesis, was confronted with the stone face of a verdict.

So it is with some trepidation tinged with hope that I read the Guardian’s Environment Correspondent Leo Hickman. The subject has been judged by him and ‘My Verdict’ delivered, and there are immediate grounds for appeal.

1998 And All That

Hickman says that the “global warming has stopped” line from climate sceptics has always hung its hat heavily (and conveniently) on the freakish anomalous (freakish and anomalous!) year of 1998 as its starting point and baseline.

M’lud. I beg to differ. In fact I go so far as to say it’s nonsense and I call exhibit 1 – the data. Look at it (the Hadcrut3 and 4 databases) and you will see if you do the statistics 1998 makes no difference to the recent temperature standstill. Sure you can use this record year as a start point and its all downhill from there, but that would be an idiotic cherry-picking thing to do.

Some start their analysis in 2001 to avoid the 1998 problem and they see the temperature standstill clearly. Others point out that because 1998 was a very warm year followed by the much cooler 1999 and 2000 then they statistically compensate for each other. That’s why one can go backwards from today and ask when there is statistical evidence for a gradient, allowing for errors. This way one arrives at no warming since 1997. 1998 was a very unusual year, perhaps a once in a century event, and isn’t it curious it divides two temperature regimes.

But as for providing the basis for the global warming has stopped idea it is not guilty.

Lies, Damned Lies And…

If I may crave the court’s indulgence a little further M’lud let me deal with the verdict that the idea that average global temperatures having “stopped” recently is “statistical sleight of hand,” as Hickman asserts.

Not so. The statistics are clear. The fact is that there has been no warming of the globe for 15 years or in other words, the increase in average global temperatures has stopped (no quotes). Hickman says the rate of decadal rise has slowed down over the past decade or so. He’s right. In the past decade the rate or rise has slowed down – to zero. What happened before this period and what might happen in the future are different matters. Looked at since 1980 the rate of rise is positive, looked at since 1997 it is zero. That’s not a skeptical opinion or analysis. That M’lud is a fact.

Hickman says that, “It also strikes me as complacent, or even reckless, to assume that any slowing is proof that global warming is nothing to worry about.” May I introduce exhibit 2 – the peer-reviewed scientific literature.

There are many, many papers discussing how long a standstill would have to go on for before it starts to conflict with climate models. When the standstill was about a decade many, including the Met Office, stated that they could explain a decadal hiatus as it occurred in model runs in about one in eight decades. Standstills of 15 years however never occurred. Some scientists thought 15 years was the time to get worried. When some scientists published a paper suggesting a much longer standstill based on oceanic temperature cycles vast amounts of opprobrium were heaped upon them, and some said the paper should never have been published.

But then the standstill went on for another year, and another one, and another one.

What happened then was interesting. In public, not in the peer-reviewed scientific literature, some started talking as if 15 years was OK even though there was little evidence it was. One paper said 17-years was the period of no warming at which we should be worried even though it was not based on the usual dataset, and we are close to that now.

So, your honour, far from being complacent or reckless an undertaking the length of a temperature standstill is crucial to test the climate models on which future climate forecasts depend. The longer it goes on the more in conflict it is with the models and the more it is telling us that we have it wrong. I note as an aside M’lud that no one predicted a 15-year standstill.

Surely the temperature has to start going up. That’s what all the current fuss is about. A few years ago the Met Office said that most of the following five years would be record breakers. When it was obvious they were wrong a new model said there would be no change. It is not a “minor downward adjustment” as Hickman calls it. It’s the difference between record warming and no warming, the difference between our understanding and ignorance of the science. Say what you will about regional climate change, accumulating energy in the system, natural fluctuations, man-made aerosols etc, the temperature has to rise eventually.

Risk analysis, preparing for the worst are political decisions. What the apolitical scientist wants to know is precisely what is going on. We are all, sceptic or otherwise, waiting for the global temperature to rise. We have been since 1997.