This is
a preamble to my forthcoming series on climate change and green polices. I only
want to make one key point here - that despite what the vast majority of people
involved in these debates will tell you to the contrary - any future
discussions about climate change polices are not primarily
discussions about risk, they are primarily discussions about uncertainty. I'll explain.
Some in
the green contingent say they are fairly certain of the negative effects on the
climate in the forthcoming decades, which, according to them, justifies radical
climate change policies in the here and now. Others say there is real
uncertainty about how bad things are going to get in the future, which, also
according to them, justifies climate change policies in the here and now. They
can't have it both ways: they can't use both near-certainty and
near-uncertainty to argue for a policy. Professor Lord Stern falls in the latter
camp, holding the absurd idea that uncertainty should generate extra radicalisaton
in the present - an idea he promulgated when he was adviser to the UK
Government on climate change: "Uncertainty of impacts strengthens the
argument for mitigation", he (in)famously said.
Professor
Stern is wrong; uncertainty of the impact of climate change strengthens the
argument for non-mitigation, not mitigation. This rule doesn't apply in every
sense, of course - sometimes uncertainty should engender extra caution. If I
can't remember if I locked the front door, it is a good idea to go back and
check. If I have increased knowledge that burglars are on the prowl that day
then that should increase my urgency to go back and check the door is locked. But
unlike the situation with the front door, where I know that a locked door is
more desirable than an unlocked door, I don't know if the costly and
economically-inefficient climate change policies are more desirable than undesirable,
because we lack the information to calculate the risks.
To not
understand in the way that professor Stern is not understanding this is to
mistake risk and uncertainty. Risk is assessing the potential costs with known
probability. Uncertainty, on the other hand, is not knowing the probability, which
means an inability to calculate a risk. If I have to draw a Jack, Queen or King
card from a 52 card deck to win £1,000,000 or else die, that is a ‘risk’ because
I can calculate the probability (12 in 52). On the other hand, if I have to
draw a Jack, Queen or King card from an unspecified pile of cards, and I don't
know how many are missing from the pack, then I have ‘uncertainty’. I cannot
calculate the probability of drawing a picture card because I don't know if any
picture cards have been removed.
Let me
make it even clearer with an illustration. Suppose there is a pile of 99 cards
- all of which are either a Jack, a Queen or a King, and all three cards are
represented. You know that 33 of the cards are Jacks, but you don't know the
ratio of Queens and Kings in the remaining 66
cards. You can choose from two scenarios:
Scenario 1: You win £1,000,000 if you draw a Jack, and nothing if you draw a Queen or King.
Scenario 1: You win £1,000,000 if you draw a Jack, and nothing if you draw a Queen or King.
Scenario
2: You win £1,000,000 if you draw a Queen, and nothing if you draw a Jack or
King.
Which scenario
would you prefer? Due to scarcity of information there really is no way to know
which scenario is preferable because you don't know the ratio of Queens and Kings - you only know there are 33 Jacks. If
you choose Scenario 1 you know you have a 1 in 3 chance of £1,000,000. If you
choose Scenario 2 you don't know what chance you have because you don't know
how many of the remaining 66 cards are Queens
- there could be as few as 1 or as many as 65. Scenario 1 offers you a risk;
Scenario 2 offers you uncertainty.
The
climate change assessments are generally more like Scenario 2 than Scenario 1 - they
involve uncertainties where drastically little is understood about the probability. It was
important to mention that before we got under way with the series. In the next
part I will look at how mindful we should be of future generations, and what we
owe them.
