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Richard Tol: Submission to Parliamentary Inquiry into the IPCC
Reposted from Richard Tol’s blog
I welcome the inquiry by the Select Committee into the Intergovernmental Panel on Climate Change. The focus of the inquiry is on Working Group I of the IPCC and its Fifth Assessment Report, neither of which are in my core areas of experience and expertise. I was a contributing author to IPCC WG1 AR3; I was a lead author in a few reports of WG2 and WG3; I am currently a convening lead author for WG2 AR5. I will therefore address only a few of the issues raised by the Select Committee.
· How effective is AR5 and the summary for policymakers in conveying what is meant by uncertainty in scientific terms ? Would a focus on risk rather than uncertainty be useful?
The agreed distinction between risk and uncertainty goes back to Knight (1921), with risk characterized by known probabilities (the throw of a dice) and uncertainty by unknown probabilities. Climate change is better described by uncertainty than by risk. In other arenas the IPCC has tried to redefine widely accepted concepts (e.g., vulnerability) which has led to endless, fruitless discussions on semantics. It would be regrettable if the IPCC would repeat this mistake with regard to risk and uncertainty.
· Do the AR5 Physical Science Basis report’s conclusions strengthen or weaken the economic case for action to prevent dangerous climate change?
IPCC WG1 AR5 is silent on this matter. The IPCC cannot make a case for action without violating its mandate; and if anything, such a case would follow from an assessment of the material in the reports of all three working groups. The IPCC cannot assess whether climate change is dangerous or not, because “danger” is a value-laden concept that, per Arrow (1962), cannot be defined for a society.
· What implications do the IPCC’s conclusions in the AR5 Physical Science Basis report have for policy making both nationally and internationally?
None. IPCC WG1 AR5 has added little to AR4 that would shift the established positions on climate policy, either nationally or internationally.
· Is the IPCC process an effective mechanism for assessing scientific knowledge? Or has it focussed on providing a justification for political commitment?
Neither. The IPCC process assesses scientific knowledge according to a political time-scale. That implies that parts of the literature are assessed too frequently while other parts of the literature are not assessed frequently enough. Instead of a mega-report every 6-7 years, it would be better to have an IPCC Journal with frequent updates where the literature moves fast and infrequent updates where little new is written.
Political positions are driven by power relations and the views of the electorate. The typical voter does not read the IPCC reports, but only casts a glance at what some journalist made of the IPCC press release.
The IPCC reports do justify the existence of a large bureaucracy which, judging from the lack in progress in reducing greenhouse gas emissions and vulnerability to climate change, seems primarily occupied with maintaining and expanding said bureaucracy.
· Is the rate at which the UK Government intends to cut CO2 emissions appropriate in light of the findings of the IPCC AR5 Physical Science Basis report?
Per Weitzman (1972), the UK should set an appropriate trajectory for a carbon price, rather than for greenhouse gas emissions. If the UK chooses to persist in its mistake of emissions targets, it should inform that decision with an assessment of the reports of all three working groups, and particularly WG3.
· What relevance do the IPCC’s conclusions have in respect of the review of the fourth Carbon Budget?
None. At a stretch, IPCC WG1 AR5 may have something to say about a long-term global carbon budget. However, a decade of British emissions is very small relative to a century of global emissions.
The UK could be a leader in international climate policy if it would demonstrate that greenhouse gas emissions can be cut substantially without causing economic pain. Current UK climate policy shows the opposite: Climate policy can cause real hardship without making a dent in emissions.
Source: http://tallbloke.wordpress.com/2013/12/10/richard-tol-submission-to-parliamentary-inquiry-into-the-ipcc/
