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about them, when they remain the gospel of the climate science establishment in general
and of the IPCC in particular.
But Stern is right in this sense: unless you assume that we may be heading for a
CO
2
-induced planetary catastrophe, for which there is no scientific basis, a policy of
decarbonisation cannot possibly make sense.
A similar, if slightly more sophisticated, case for current policies has been put forward
by a distinctly better economist than Stern, Harvard's Professor Martin Weitzman, in what
he likes to call his 'dismal theorem'. After demolishing Stern's cost-benefit analysis, he
concludes that Stern is in fact right but for the wrong reasons. According to Weitzman, this
is an area where cost-benefit analysis does not apply. Climate science is highly uncertain,
and a catastrophic outcome which might even threaten the continuation of human life
on this planet cannot be entirely ruled out however unlikely it may be. It is therefore
incumbent on us to do whatever we can, regardless of cost, to prevent this.
This is an extreme case of what is usually termed 'the precautionary principle'. I have
often thought that the most important use of the precautionary principle is against the
precautionaryprincipleitself,sinceitcanalltooreadilyleadtoabsurdpolicyprescriptions.
In this case, a moment's reflection would remind us that there are a number of possible
catastrophes, many of them less unlikely than that caused by runaway warming, and all of
them capable of occurring considerably sooner than the catastrophe feared by Weitzman;
and there is no way we can afford the cost of unlimited spending to reduce the likelihood
of all of them.
In particular, there is the risk that the earth may enter a new ice age. This was the fear
expressed by the well-known astronomer Sir Fred Hoyle in his topic
Ice: The Ultimate
Human Catastrophe
, and there are several climate scientists today, particularly in Russia,
concerned about this. It would be difficult, to say the least, to devote unlimited sums to
both cooling and warming the planet at the same time.
Attheendoftheday,thiscomesdowntojudgment.Weitzmanisclearlyentitledtohis,
butIdoubtitiswidelyshared;andifthepublicwereawarethatitwasonthisslenderbasis
thattheentirecaseforcurrentpoliciesrestedIwouldbesurprisediftheywouldhavemuch
support.
Rightly so. But there is another problem.
Unlike intelligent adaptation to any warming that might occur, which in any case will
mean different things in different regions of the world, and which requires no global
agreement, decarbonisation can make no sense whatever in the absence of a global
agreement. And there is no chance of any meaningful agreement being concluded. The
very limited Kyoto accord of 1997 has come to an end; and although there is the declared
intention of concluding a much more ambitious successor, with a UN-sponsored
conference in Paris 2015 at which it is planned that this should happen, nothing of any
significance is remotely likely.
