The science was settled ten years ago, but it takes ten years to filter through. The economics, however, lag. We’re starting to have some good answers to “how much will it cost”. The answer, probably, is that it will cost one hell of a lot more to let climate change hit us, than it will to do something about it.
And by “one hell of a lot more”, we’re talking tens of trillions of dollars. Possibly hundreds.
Getting that message across is the next step, coz if it takes ten years for this answer to filter its way through to voters… that’s ten years more emissions and ten years closer to the tipping points, whereupon the cost really start to go up.
Anyway, this week’s editorial:
Climate change editorial – the new questions
The debate about climate change has moved on from ‘is it happening’, to the much harder questions of ‘how many emissions are too much?’, ‘how much is it going to cost?’, ‘what to do about it?’, and ‘who should pay?’ Last week saw an Institute of Policy Studies workshop to bring together a broad range of experts to address these questions. We will summarise some of this policy debate over the next few weeks.
The first question is what to do about it? Reducing net emissions is the answer, but how much is needed? The EU set an increase of two degrees Celsius as a dangerous level not to be exceeded. Can we keep to that? We have already had a 0.6 degree Celsius increase over pre-industrial levels, which doesn’t leave us much room to move.
We are already at a concentration of 425 ppm of carbon dioxide equivalent (including the effect of other greenhouse gases) and climbing at more than 2.5 ppm each year. How much more is too much? The size of response of the climate to greenhouse gases is uncertain, so we cannot say what level of emissions is safe. However, that uncertainty has been well studied and we can say that, for example, a rise of greenhouse gases to 500 ppm will imply a 70% chance of exceeding the 2 C target. A rise to 450 ppm will mean a 50% chance. These percentages are themselves uncertain, but it is clear that there are big risks with any increase of emissions.
Stabilising greenhouse gases at 500 ppm by reducing emissions seems technically feasible. The barriers are political and behavioural and they are substantial but stabilisation at 500 ppm still gives high risks of severe impacts. Stabilising at 450 ppm looks hard, but may be necessary to give us a fair chance of avoiding the worst effects.
A final note – delaying action means that by the time we start cutting emissions, there will already be more carbon in the atmosphere. Thus delay requires much harsher cuts. The time to start was yesterday. Is starting today going to be good enough?
Ah, f’it, kittens: