The global scientific consensus is that man's habit of belching greenhouse gases into the atmosphere is destabilising the climate. To save ourselves from catastrophe we must urgently cut those emissions. Governments must set binding targets to achieve those cuts. That is broadly the international political consensus too, with two caveats. The US does not want to commit to targets independent of the developing world, which is catching up fast in terms of carbon output. And developing countries, chiefly China and India, reserve the right to catch up with the West before subjecting themselves to the same level of carbon austerity.
The Bali compromise, roughly speaking, is that rich nations agree to transfer green technology to poorer ones and specific targets for emissions cuts - championed by the EU - are relegated to a footnote.
The US, China and India, are labouring under a false assumption - that cutting emissions means surrendering economic virility. But once the disastrous consequences of inaction are taken into account - natural disasters; refugee crises; food shortages - it becomes clear that, aside from the moral imperative, there is a huge competitive edge available to the countries that first make the transition to a low-carbon economy.
Thankfully, American public opinion, and some individual US states, which have set unilateral emission targets, are closer to understanding this than George Bush and his administration. The next US President, whether Republican or Democrat, will surely take note of that
Sceptics are right to worry that Bali did not deliver a carbon-cutting breakthrough. But as a statement of intent it signals real progress. At least politicians are catching up with the basic science of climate change. Now they just need to catch up with the scientists' - and increasingly the public's - sense of urgency.