Figure 1.4 from Chapter 1 of a draft of the Fifth Assessment Report from the Intergovernmental Panel on Climate Change. Initials represent the First Assessment Report (FAR) in 1990, the Second (SAR) in 1995. Shaded banks show range of predictions from each of the four climate models used for all four reports since 1990. The last report, AR4, was issued in 2007. The black squares, shown with uncertainty bars, measure the observed average surface temperatures over the same interval. The range of model runs is indicated by the vertical bars. The light grey area above and below is not part of the model prediction ranges.
By Reiner Grundmann | September 19, 2013
With the fifth assessment report soon to be released by the IPCC the pre-publication buzz is well underway. A while ago unauthorised drafts circulated in the blogosphere and now the official leaks have found their way into news editing rooms. A central question picked up by most commentators is the ‘pause in global warming’, the ‘stagnation’, or the ‘hiatus’.
An anomaly presents itself for climate science in that model projections about future temperature increases do not concur with actual temperature observations. As expected, comments align with the agendas of the commentators, depending if one wants to defend the official modelling output or criticise it. These agendas are closely linked to policy options and the question if a lower observed temperature trend provides justification for political action on greenhouse gas emissions.
On this blog Hans von Storch expressed optimism as regards the ability of climate science to deal with this anomaly: ‘Eventually, we need to evaluate the different suggestions, but that will need time. No doubt that the scientific community will achieve this.’ Others are quick to pronounce climate science bunk. David Rose wrote in the Daily Mail ‘A leaked copy of the world’s most authoritative climate study reveals scientific forecasts of imminent doom were drastically wrong.’ Hayley Dixon in The Telegraph put it less blatant but still succinct in her opening sentence: ‘A leaked draft of a report by the UN Intergovernmental Panel on Climate Change is understood to concede that the computer predictions for global warming and the effects of carbon emissions have been proved to be inaccurate.’
Of course, both papers are on the political right and often skeptical about efforts to curb greenhouse gas emissions. It seems as if this topic is inconvenient for the left leaning papers who support action on climate mitigation. The Guardian so far is silent on the issue and prefers to write about new record lows of Artic Ice coverage. When it looked last at this issue, Fiona Harvey bolstered the heat uptake by the oceans as explanation for the pause in global warming, thus doing away with a potential anomaly. At the same time she claims that climate scientists point out ‘that the trend is still upwards, and that the current temperature rises are well within the expected range.’ A quick glance at the graph above shows this is an illusion (the grey upper and lower bands are not part of the model prediction range).
Both the Mail and Telegraph quote Myles Allen (Oxford University) who tries to put the IPCC and its work into perspective. Says Allen: ‘we need to look very carefully about what the IPCC does in future… It is a complete fantasy to think that you can compile an infallible or approximately infallible report, that is just not how science works. It is not a bible, it is a scientific review, an assessment of the literature. Frankly both sides are seriously confused on how science works – the critics of the IPCC and the environmentalists who credit the IPCC as if it is the gospel.’
The Mail quotes Judy Curry (Georgia Institute of Technology) saying it makes ‘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.’
Both Allen and Curry call for a radical reform of the IPCC with Curry being more specific: ‘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.’
Meanwhile in the Financial Post, Ross McKitrick wrote: ‘As the gap between models and reality has grown wider, so has the number of mainstream scientists gingerly raising the possibility that climate models may soon need a bit of a re-think. A recent study by some well-known German climate modellers put the probability that models can currently be reconciled with observations at less than 2%, and they said that if we see another five years without a large warming, the probability will drop to zero.’ (this seems to be a reference to the paper by Hans von Storch and Eduardo Zorita recently presented here on Klimazwiebel).
McKitrick goes on: ‘Judging by the drafts circulated this year, [the IPCC] is in full denial mode. Its own figure reveals a discrepancy between models and observations, yet its discussion says something entirely different. On page 9 of Chapter 1 it explains where the numbers come from, it talks about the various challenges faced by models, and then it sums up the graph as follows: “In summary, the globally-averaged surface temperatures are well within the uncertainty range of all previous IPCC projections, and generally are in the middle of the scenario ranges.” Later, in Chapter 9, it states with “very high confidence” that models can correctly simulate global surface temperature trends.’
McKitrick then makes a link between a ‘failed science’ and a ‘costly policy’: ‘since we are on the verge of seeing the emergence of data that could rock the foundations of mainstream climatology, this is obviously no time for entering into costly and permanent climate policy commitments based on failed model forecasts. The real message of the science is: Hold on a bit longer, information is coming soon that could radically change our understanding of this issue.’
This is where the crux of the matter lies. While it is indeed highly problematic to tie costly policies to flawed model forecasts the prospects of climatology are perhaps worth considering.
I chose as title for this blog post ‘The coming Crisis of Climate Science?’ The question mark is intentional and important. It could well be that in the coming year global surface temperatures pick up as expected. Existing models would be vindicated, end of story. The question is: how many more years should climatologists wait for this ‘renormalization’? It appears that mood is shifting towards alternative models and explanations. The timing of the fifth assessment report falls into this critical juncture where a lot of momentum has built up in favour of the current modelling practices which now prove so elusive. While the IPCC tries to make last minute rhetorical adjustments in order to accommodate anomalies, some of its participants, looking beyond, already indicate that this institution may have run its course. But even if the IPCC was reformed or dissolved, we still would have these questions in front of us:
How convincing is the climate science? How important should it be for climate policies? Do we need to implement climate policies, and if so, what should they be?
I can envisage an irony of history where climatology enters a period of crisis and looses its central place in public discourse about climate change, thus opening up discursive spaces for pragmatic options to deal with the problem.