Roger Pielke has a rather odd post over at Prometheus. To me, it seems that he is riding his hobby horse (the "honest broker") rather hard. What is he complaining about? That the recent steering committee report of the Exeter conference: Avoiding Dangerous Climate Change mentions stabalising (equivalent) CO2 levels:
Limiting climate change to 2 deg C implies stabilizing the atmospheric concentration of all greenhouse gases. The CO2 concentration must not exceed 500ppmv, if the climate sensitivity is 2.5 deg C. Global emissions would need to peak in 2020 and decline to 3.1 GtC/year by 2095... Major investment is needed now in both mitigation and adaptation. The first is essential to minimise future impacts and the latter is essential to cope with impacts which cannot be avoided in the near to medium term.”.
(Thats quoting RP quoting the report; if you want to read the uninteresting bits in the ..., then see the report itself). But this is innocuous (at least the bit before the ...): its just a statement of fact (or rather, of the current best-guesses at fact). RP concludes:
If the Exter conference is indicative of the direction that the IPCC will be taking in its Fourth Assessment Report, then it will be remembered as a key milestone in the continuing evolution of the IPCC from honest broker to political advocate.
Which is weird. Because it wasn't an IPCC conference at all. It was sponsored by DEFRA. The steering committee was chaired by someone from the OECD and none of them list IPCC affiliations; the report that RP dislikes so much is also pretty innocuous. The last sentence that RP quotes looks like it was stuffed in by the politicoes, but quite why he blames IPCC for that I don't know. Adding the "If..." just about saves it, but his thrust is clear and I simply can't agree with it.
If you read the keynote presentation by Pachauri (who identifies himself with IPCC) you find "defining dangerous is a value judgement" and "Can a temperature target capture the limits
dangerous?" (unfortunately I don't know exactly what he said there, as I only get the bullet points of the presentation) - these are exactly the points that RP himself is keen on, but he gives Pachauri no credit for this.
In fact, it all looks like at attempt to fulfill the second part of his prophecy:
So if the conference reports scientific understandings and uncertainties for emissions stabilization scenarios related to (a) a magical instantaneous ending of CO2 emissions, (b) unrestrained emissions (a maximum scenario), and (c) everything in between, then it would clearly give policy makers a sense of what science can say about stabilization scenarios and their consequences. This information would allow policy makers in the the UK, or any other country, to debate and discuss the concept of "dangerous climate change" and, if desired, work towards a political consensus. Such a perspective would be a valuable outcome of the meeting.
But if the meeting results in a recommendation for stabilization at one particular concentration level over others, and increasingly we hear calls for a 2 degree/400 ppm target, then the meeting will have devolved into an exercise in political advocacy under the cover of the authority of science and scientists.
And if you read the report, it fulfills part I of his prophecy. But you wouldn't guess that from his follow-up post.