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.
Add a comment