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David Whitehouse: Raptures Of The Deep

Dr David Whitehouse

The three briefing papers on the recent pause in global surface temperature released by the UK Met Office this week make interesting reading. They can be found here, here and here.

But perhaps unintentionally they say more about the messenger than the actual science, of which there is very little that is new. The overall message (reached with the considerable help of hindsight for no one predicted it) is that the current standstill in global surface temperature is nothing unusual, can be explained quite simply by climate models, has its explanation in the heat uptake by the deep oceans, and ultimately doesn’t make much difference. After many years of denying that the standstill existed the Met Office now seeks to explain it, and bring it into the fold.

The problem with all this is that after such confident assertions, the actual evidence, as the reports eventually confirm, doesn’t merit such conclusions. The reports seem to push their favourite explanation strongly, and then less enthusiastically state elsewhere that such conclusions are premature.

This leads one to question why the reports have been written, as apart from details about a climate simulation model (unpublished in peer-reviewed literature) they contain nothing new. The Met Office recently said it was ‘loosing the PR war’ because it had been concentrating on arguments about global surface temperature. Perhaps this is part of a fight back?

Scientifically it adds nothing, but it is a report stamped with the Met Office’s authority and released to journalists at a press conference at the UK Science Media Centre a day before the reports were available to the public. Wasn’t it the Science Media Centre that recently testified before MPs that ‘sceptics’ had been using the global temperature standstill to undermine climate science?

Pick Your Coincidence

A careful eye sees the lack of internal consistency in the reports. One of the reports says the temperature has been ‘relatively flat’ over the past 15-years to 2013. It is not ‘relatively’ flat, it is flat. Later on the Met Office claims that the standstill is not 15 years, but since 2001.

Part 1 is the ‘State of the Climate,’ and it is interesting to see the range and variation of the numerous climate variables mentioned. There is a lot of disagreement between them. Looking at them makes one realise what a big deal, and a big clue, is the recent temperature standstill.

Part 2 states: “Observations of Ocean Heat Content (OHC) and Sea Level Rise (SLR) suggest that the additional heat from the continued rise in atmospheric carbon dioxide concentration may have been absorbed in the ocean and not been manifest as a rise in surface temperature.”

There are many problems with this statement which are not addressed by this report. It presents SLR from 1992 only – the satellite era. Omitted are the previous 100 years of data based on tidal gauges. It is perfectly reasonable to analyse the SLR data and find no increase in its rate of rise in recent decades (in fact quite the opposite might be happening) and deduce that there is no anthropomorphic signal in the data. So how exactly does the Met Office’s conclusion work given that there is a rise in OHC in recent decades and no increase in the rate of SLR?

The problem with OHC is that the data is not up to drawing good conclusions. It is also contradictory. The Met Office takes the start of the pause as 2001, which is coincident with an observed maximum in ocean heat uptake in 2002 (from what data is available). The problem is that the pause, most of it, has continued long after 2004 when the oceans upper layer heat uptake declines. Despite the explanation of the pause in ocean heating is suffused throughout the report, buried within it is the statement that they, “cannot show definitely that this has been the dominant factor in the recent pause.” So there you have it. The ocean uptake is a unproven hypothesis, like so many others. I bet that wasn’t a headline used in the newspapers.

The report says that the pause could be caused by a combination of changes in the total energy received by the planet and under-surface ocean heating. Explaining the pause this way makes its most interesting property – that it’s statistically constant – seem a strange situation, begging the question how could two competing factors exactly balance themselves for 16 years!

The report states that there have been pauses before, notably between 1940 and the late 1970s. They attribute this to aerosols reflecting sunlight. Their confidence in this explanation is far too strong given that this pause is poorly understood and there are many problems with the aerosol explanation. On this point the report is comparing apples and oranges as the 1940 pause occurred at a time when the IPCC says that greenhouse gasses had only a tiny effect on the climate, wheras the post-1980 warming – which includes the post-1997 standstill – has occurred in the era where climate is dominated by greenhouse gasses. In short, the two pauses are not comparable.

Dancing Like It’s 1998

It makes the old mistake of referring to 1998 – the year of the super El Nino – as some kind of starting point for the standstill. This is a common error. It also says that the start of the current pause is difficult to determine precisely. Well actually it isn’t. It started in 1997. The following year saw the great El Nino, but statistically this was offset by 1999 and 2000 that were La Nina years.

The only new thing in the three reports are the results from a single climate model that was run thousands of times and was in some cases able to reproduce something like the standstill giving a ten-year pause about twice a century. But what does this prove? Than an (unpublished) model kind of works. It would be surprising given the number and spread of results from climate models if some of them didn’t conform to the observations. However, what we have is a 16-year hiatus, not a ten-year one, and that makes a big difference.

Later on the report goes into climate sensitivity and dismisses all recent research papers indicating lower climate sensitivity that was thought. They also, according to Nic Lews one of the authors of Otto et al 2013, misrepresent the findings of that study.

In its conclusions the Met Office states that the pause has not falsified the climate models. If the pause is, as they define it and limit it, from 2001 onwards, then this is true. But if the pause is 16-years, as the temperature data actually show, then the models, already looking unimpressive, are in jeopardy.

We are at the waiting stage. Better and more reliable OHC data are desperately needed. Even if global temperatures were to rise again the climate models have shown themselves inadequate. If the pause continues, however, then the crisis of climate science will become more serious.