The latest and most authoritative assessment of what it will cost to protect developing countries from a two degree rise in global temperatures is from the World Bank. This week the World Bank released a report estimating that $75-100bn per year would be required for climate adaptation assistance from 2010-2050.

That figure does not include the cost of assisting developing countries to reduce their own carbon emissions.

The quantum is mind-boggling — or, at least, would have been until the second half of 2008. The global financial crisis recalibrated our sense of proportion in financial matters.

In August, the IMF calculated that developed countries — Europe, the UK, and most of all the United States — had spend US$10.2 trillion bailing out their banks.

A least $2 trillion more has been spent propping up demand and employment in western countries.

Add to that the nebulous but similar-sized liability of bank guarantees on public balance sheets across the globe.

In those terms, a total climate aid bill of $4 trillion between now and mid-century starts to look altogether more manageable.

Western nations, however, don’t appear to want to know about it — and Australia is worst of all. Beyond the $150m we’re providing to the Pacific — partly out of self-interest — Australia hasn’t made any commitment to provide any assistance beyond that needed to ensure it can buy lots of carbon permits from PNG and Indonesia.

Another indication of just how serious this Government is about climate change.