by Judith Curry
The latest data release from HadCRUT4 is creating quite a stir.
David Rose has published a provocative article in the Daily Mail entitled Global warming stopped 16 years ago, reveals Met Office report quietly released . . . and here is the chart to prove it. The two main people that were interviewed were myself and Phil Jones. Here is the meat of the article in terms of my and Phil Jones’ statements:
‘The new data confirms the existence of a pause in global warming,’ Professor Judith Curry, chair of the School of Earth and Atmospheric Science at America’s Georgia Tech university, told me yesterday.
‘Climate models are very complex, but they are imperfect and incomplete. Natural variability [the impact of factors such as long-term temperature cycles in the oceans and the output of the sun] has been shown over the past two decades to have a magnitude that dominates the greenhouse warming effect.
‘It is becoming increasingly apparent that our attribution of warming since 1980 and future projections of climate change needs to consider natural internal variability as a factor of fundamental importance.’
Professor Phil Jones, director of the Climate Research Unit at the University of East Anglia, who found himself at the centre of the ‘Climategate’ scandal over leaked emails three years ago, would not normally be expected to agree with her. Yet on two important points, he did.
The data does suggest a plateau, he admitted, and without a major El Nino event – the sudden, dramatic warming of the southern Pacific which takes place unpredictably and always has a huge effect on global weather – ‘it could go on for a while’.
Like Prof Curry, Prof Jones also admitted that the climate models were imperfect: ‘We don’t fully understand how to input things like changes in the oceans, and because we don’t fully understand it you could say that natural variability is now working to suppress the warming. We don’t know what natural variability is doing.’
Yet he insisted that 15 or 16 years is not a significant period: pauses of such length had always been expected, he said.
Yet in 2009, when the plateau was already becoming apparent and being discussed by scientists, he told a colleague in one of the Climategate emails: ‘Bottom line: the “no upward trend” has to continue for a total of 15 years before we get worried.’
But although that point has now been passed, he said that he hadn’t changed his mind about the models’ gloomy predictions: ‘I still think that the current decade which began in 2010 will be warmer by about 0.17 degrees than the previous one, which was warmer than the Nineties.’
Only if that did not happen would he seriously begin to wonder whether something more profound might be happening. In other words, though five years ago he seemed to be saying that 15 years without warming would make him ‘worried’, that period has now become 20 years.
Meanwhile, his Met Office colleagues were sticking to their guns. A spokesman said: ‘Choosing a starting or end point on short-term scales can be very misleading. Climate change can only be detected from multi-decadal timescales due to the inherent variability in the climate system.’
He said that for the plateau to last any more than 15 years was ‘unlikely’. Asked about a prediction that the Met Office made in 2009 – that three of the ensuing five years would set a new world temperature record – he made no comment. With no sign of a strong El Nino next year, the prospects of this happening are remote.
Overall, I would say that this is a very good article; I think the exchange between me and Jones, mediated by Rose, is an important one. However, I am not happy with this statement in the early part of the article:
Some climate scientists, such as Professor Phil Jones, director of the Climatic Research Unit at the University of East Anglia, last week dismissed the significance of the plateau, saying that 15 or 16 years is too short a period from which to draw conclusions.
Others disagreed. Professor Judith Curry, who is the head of the climate science department at America’s prestigious Georgia Tech university, told The Mail on Sunday that it was clear that the computer models used to predict future warming were ‘deeply flawed’.
I have no idea where the ‘deeply flawed’ came from, I did not use these words in any context that Rose should be quoted (perhaps I used them somewhere on my blog?) Also, I agree that 16 years is too short, given the timescales of the PDO and AMO, to separate out natural versus anthropogenic variability (but this cuts both ways: the warming period between 1980 and 1998 was arguably amped by the PDO and AMO). And while I am griping, why did he have to use that photo that makes me look like a gorgon :( .
Here is the text I emailed Rose, in response to his questions:
The UK Met Office has responded to Rose’s article with this statement.
For context on this issue, see these previous Climate Etc. posts: