As the FT pointed out in an editorial yesterday, scepticism of the reality of climate change is either unfounded or, when warranted, does not mean nothing needs be to be done. We cannot be certain (until it is too late) that continuing to emit carbon at our current pace will lead to disaster; but we do know that if we do, the chance of a catastrophic outcome is high enough to make insuring against worst-case scenarios the rational response. Surely the financial crisis has taught us that a low-probability tail risk is still a risk.

As there is no one onto whom planetary risk can be shifted, the only way to insure against climate change fall-out is to make it sufficiently improbable. The upcoming summit on climate change in Copenhagen is the world's opportunity to do this, by making a mutual, binding commitment to global cuts in carbon emissions.

In order to prevent catastrophe, it does not matter how or by whom the reduction is achieved: it is the world as a whole whose emissions must peak in the next decade and more than halve by mid-century, according to scientists.