A dragon was buried at the Paris climate meeting (COP21): 'climate sceptics' disappeared. Now we face a second, equally formidable dragon: unreasonable optimism about 'new' energy technologies. This optimism supports economic-growth models driven by innovation, but depends on an unimaginable scale and rate of deployment.

Defeating the second dragon requires that we reconsider our habits of energy usage. Thirty years of engine-efficiency gains have been eclipsed by our preferences for ever-larger cars that are often 20 times heavier than the passengers — but these are habits, not needs.

We could continue to live well in rich economies with, say, one-quarter of the energy. For instance, we could run the boiler for one-quarter of the time and quarter our movement of mass — the total of all vehicles, freight and people, measured in tonne-kilometres. We could also make buildings and goods with half the material (without risking safety) and keep them for twice as long.

'Success' today is largely associated with derivative measures of increasing gross domestic product, profitability, speed or salary. Yet our value systems are based on integral measures of quality and stock: reputation, heritage, journeys and relationships. We need to expand the dialogue of climate mitigation to reflect these values. Challenging our habits of energy use should be the first priority of climate policy.