Those of us who give a damn are turning these problems over and over in our minds every day. It seems to me, now, that the problems we face are less to do with technology and more to do with religion: specifically the religious belief that nature owes us a living, that endless GDP growth is our birthright, that we can have our cake and eat it too.

Changing that myth - that mindset - is the most profound and urgent challenge that our species has ever faced.

As a climate activist myself, the hardest step was to accept the need to change my own lifestyle - to stop flying and ditch all but the most important driving. To buy local. To ditch consumerism . I'm still struggling with that.

Unless people learn to be happy and fulfilled with less stuff and less mobility (ie. less energy consumption), debating about which technology mix to employ is futile, and we'll just blunder on into disaster.