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.
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.
One of the IPCC report’s own authors, Professor Myles Allen, the director of Oxford University’s Climate Research Network, 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.’