After hearing his lecture last Wednesday, I understood why: he is telling governments, business, and his fellow economists what it is they want to hear, i.e. that we don't have to question the economic foundations and basic assumptions on which our civilization and the lifestyles of our social and political elites (which, of course, everyone else is seeking to emulate) are based.

" . . [Prof. Sachs] gave an optimistic reading of human nature - we have coped with many disasters in the past . . . . and we can do so again - not by changing human nature but by a gradual evolution in our human institutions. I agree"

There is no time for the "gradual" evolution in our human institutions. Either we revolutionize them or join the dinosaurs!

But there is a fundamental misunderstanding here, certainly on the part of Christopher Meyer, "who described Sachs' conclusions as 'pie in the sky' because fundamentally man's nature does not change".

The point is that our economy is not rooted in our "human nature", which aspires to higher things, but developed specifically (and naturally, in view of our biological origins) to serve and exploit our primitive animal nature - which it does exceedingly well.

Never mind those still denying the reality of anthropogenic climate change: what we all need to face up to is the extent to which human behaviour, along with the social, political and economic framework within which it operates, is still rooted in and dominated by our animal nature. Once we recognise this as the "root cause" of the Sustainability Problem we can set about solving it. But not before.