Leaked IPCC Report: Scientists Got Global Warming Rate Wrong
A leaked copy of the world’s most authoritative climate study reveals scientific forecasts of imminent doom were drastically wrong.
The Mail on Sunday has obtained the final draft of a report to be published later this month by the UN Intergovernmental Panel on Climate Change (IPCC), the ultimate watchdog whose massive, six-yearly ‘assessments’ are accepted by environmentalists, politicians and experts as the gospel of climate science.
They are cited worldwide to justify swingeing fossil fuel taxes and subsidies for ‘renewable’ energy.
Yet the leaked report makes the extraordinary concession that over the past 15 years, recorded world temperatures have increased at only a quarter of the rate of IPCC claimed when it published its last assessment in 2007.
Back then, it said observed warming over the 15 years from 1990-2005 had taken place at a rate of 0.2C per decade, and it predicted this would continue for the following 20 years, on the basis of forecasts made by computer climate models.
But the new report says the observed warming over the more recent 15 years to 2012 was just 0.05C per decade – below almost all computer predictions.
Nevertheless, the IPCC now maintains, again on the basis of the models, that by 2035, the world will have warmed by a further 0.4C-1.0C.
The 31-page ‘summary for policymakers’ is based on a more technical 2,000-page analysis which will be issued at the same time. It also surprisingly reveals: IPCC scientists accept their forecast computers may have exaggerated the effect of increased carbon emissions on world temperatures – and not taken enough notice of natural variability.
* They recognise the global warming ‘pause’ first reported by The Mail on Sunday last year is real – and concede that their computer models did not predict it. But they cannot explain why world average temperatures have not shown any statistically significant increase since 1997.
* They admit large parts of the world were as warm as they are now for decades at a time between 950 and 1250 AD – centuries before the Industrial Revolution, and when the population and CO2 levels were both much lower.
* The IPCC admits that while computer models forecast a decline in Antarctic sea ice, it has actually grown to a new record high. Again, the IPCC cannot say why.
* A forecast in the 2007 report that hurricanes would become more intense has simply been dropped, without mention.
This year has been one of the quietest hurricane seasons in history and the US is currently enjoying its longest-ever period – almost eight years – without a single hurricane of Category 3 or above making landfall.
One of the report’s own authors, Professor Myles Allen, the director of Oxford University’s Climate Research Network, last night said this should be the last IPCC assessment – accusing its cumbersome production process of ‘misrepresenting how science works’.
Despite the many scientific uncertainties disclosed by the leaked report, it nonetheless draws familiar, apocalyptic conclusions – insisting that the IPCC is more confident than ever that global warming is mainly humans’ fault.
It says the world will continue to warm catastrophically unless there is drastic action to curb greenhouse gases – with big rises in sea level, floods, droughts and the disappearance of the Arctic icecap.
Last night Professor Judith Curry, head of climate science at Georgia Institute of Technology in Atlanta, said the leaked summary showed that ‘the science is clearly not settled, and is in a state of flux’.
She said it therefore made no sense that the IPCC was claiming that its confidence in its forecasts and conclusions has increased.
For example, in the new report, the IPCC says it is ‘extremely likely’ – 95 per cent certain – that human influence caused more than half the temperature rises from 1951 to 2010, up from ‘very confident’ – 90 per cent certain – in 2007.
Prof Curry said: ‘This is incomprehensible to me’ – adding that the IPCC projections are ‘overconfident’, especially given the report’s admitted areas of doubt.
Head of climate science at Georgia Institute of Technology in Atlanta, said the leaked summary showed that ‘the science is clearly not settled, and is in a state of flux’
Starting a week tomorrow, about 40 of the 250 authors who contributed to the report – and supposedly produced a definitive scientific consensus – will hold a four-day meeting in Stockholm, together with representatives of most of the 195 governments that fund the IPCC, established in 1998 by the World Meteorological Organisation (WMO) and the United Nations Environment Programme (UNEP).
The governments have tabled 1,800 questions and are demanding major revisions, starting with the failure to account for the pause.
Prof Curry said she hoped that the ‘inconsistencies will be pointed out’ at the meeting, adding: ‘The consensus-seeking process used by the IPCC creates and amplifies biases in the science. It should be abandoned in favour of a more traditional review that presents arguments for and against – which would better support scientific progress, and be more useful for policy makers.’ Others agree that the unwieldy and expensive IPCC assessment process has now run its course.
Prof Allen said: ‘The idea of producing a document of near-biblical infallibility is a misrepresentation of how science works, and we need to look very carefully about what the IPCC does in future.’
Climate change sceptics are more outspoken. Dr Benny Peiser, of the Global Warming Policy Foundation, described the leaked report as a ‘staggering concoction of confusion, speculation and sheer ignorance’.
As for the pause, he said ‘it would appear that the IPCC is running out of answers . . . to explain why there is a widening gap between predictions and reality’.
The Mail on Sunday has also seen an earlier draft of the report, dated October last year. There are many striking differences between it and the current, ‘final’ version.
The 2012 draft makes no mention of the pause and, far from admitting that the Middle Ages were unusually warm, it states that today’s temperatures are the highest for at least 1,300 years, as it did in 2007. Prof Allen said the change ‘reflects greater uncertainty about what was happening around the last millennium but one’.
A further change in the new version is the first-ever scaling down of a crucial yardstick, the ‘equilibrium climate sensitivity’ – the extent to which the world is meant to warm each time CO2 levels double.
As things stand, the atmosphere is expected to have twice as much CO2 as in pre-industrial times by about 2050. In 2007, the IPCC said the ‘likeliest’ figure was 3C, with up to 4.5C still ‘likely’.
Now it does not give a ‘likeliest’ value and admits it is ‘likely’ it may be as little as 1.5C – so giving the world many more decades to work out how to reduce carbon emissions before temperatures rise to dangerous levels.
As a result of the warming pause, several recent peer-reviewed scientific studies have suggested that the true figure for the sensitivity is much lower than anyone – the IPCC included – previously thought: probably less than 2C.
Last night IPCC communications chief Jonathan Lynn refused to comment, saying the leaked report was ‘still a work in progress’.
An original version of this article sought to make the fairest updated comparison with the 0.2C warming rate stated by the IPCC in 2007.
It drew on the following sentence in the draft 2013 summary: ‘The rate of warming over the past 15 years… of 0.05C per decade is smaller than the trend since 1951, 0.12C per decade.’ This would represent a reduction in the rate of warming by a little under one half.
But critics argued that the 0.2C warming rate in the 2007 report relates only to the previous 15 years whereas the 0.12C figure in the forthcoming report relates to the half-century since 1951. They pointed out that the equivalent figure in the 2007 report was 0.13C.
This amended article compares the 0.05C per decade observed in the past 15 years with the 0.2C per decade observed in the period 1990-2005 and with the prediction that this rate per decade would continue for a further 20 years.