Readers will remember last week's joint Met Office/CEH report on the floods, of which I gave a favourable review at the time. In particular, the report noted that "As yet, there is no definitive answer on the possible contribution of climate change to the recent storminess, rainfall amounts and the consequent flooding."
What was not so good was Julia Slingo's "intepretation" of the report's contents. The BBC, among others, reported her as saying "all the evidence suggests there is a link to climate change".
Readers will also recall David Rose's report in the Mail on Sunday yesterday, which described the apparent contradictions between the views of Slingo and Professor Mat Collins of Exeter University, who was quoted as saying "There is no evidence that global warming can cause the jet stream to get stuck in the way it has this winter. If this is due to climate change, it is outside our knowledge".
Last night, Prof Collins tweeted that he and the Met Office would soon issue a joint clarification and all day today we have been waiting expectantly. The promised statement has finally been published at the Met Office blog, and it's fair to say that it's not very impressive.
The report by the Met Office states that “As yet, there is no definitive answer on the possible contribution of climate change to the recent storminess, rainfall amounts and the consequent flooding. This is in part due to the highly variable nature of UK weather and climate.” This agrees with the latest IPCC Report that states: “Substantial uncertainty and thus low confidence remains in projecting changes in Northern Hemisphere storm tracks, especially for the North Atlantic basin.”
This is the basis for Prof Collins’ comment and means that we are not sure, yet, how the features that bring storms across the Atlantic to the UK – the jet-stream and storm track – might be impacted by climate change. As the Met Office report highlights for this year’s extreme conditions, there are many competing factors – from changes in the winds of the upper atmosphere to disturbed weather over Indonesia.
What the Met Office report – and indeed the IPCC – does say is that there is increasing evidence that extreme daily rainfall rates are becoming more intense. It is clear that global warming has led to an increase in moisture in the atmosphere – with about four per cent more moisture over the oceans than in the 1970s – which means that when conditions are favourable to the formation of storms there is a greater risk of intense rainfall. This is where climate change has a role to play in this year’s flooding.
With respect to changes in storminess, the good news is that recent advances in climate science are starting to pay dividends. Improved spatial resolution in models – that means that they can model weather and climate in more spatial detail – is allowing the models to represent some of the key factors that drive regional weather patterns. As the Met Office report states ‘With a credible modelling system in place it should now be possible to perform scientifically robust assessments of changes in storminess, the degree to which they are related to natural variability and the degree to which there is a contribution from human-induced climate change.’
See that? Instead of defending Julia Slingo's statement on the floods they have defended the original report. This is very interesting: it seems that the Met Office is unable to come up with any defence of its chief scientist's public statements.
Yesterday I suggested that Slingo's statement had misled the public. This clarification doesn't seemed to have changed anything at all.
It looks bad. Very bad.