Sometimes the debate about climate change and other global challenges is couched in terms of guilt and stopping doing things. This talk argues we can be optimistic if we take a rational, scientific view, shaped by a belief in technological solutions and mathematical models. Maths in particular has a major role to play. At a basic level, as the late great David Makay once said, our main tool in understanding how to engineer a sustainable future is arithmetic; calculations involving tons of CO2, MW of energy, mean temperatures in degrees C. Further, I will also show how modern mathematical ideas in network science, control theory, artificial intelligence and the theory of tipping points all have a role to play.

• 11 years plus