There are two climate change worlds: the gritty reality of engineering and economics on one side, and the political theatre of ambition and marketing on the other. Function and symbolism. The power and the passion.

This divide is no better illustrated by the current national debate around Australia’s revised emissions reduction target of 43 per cent by 2030. Hard heads know this will be tough, if not impossible. That’s not a lack of will or moral purpose; it’s because the physical engineering required to get there sits at the edge of reality.