ABSTRACT
In the long term there is no greater risk than climate change, or other topic as important – hence this separate chapter where, as usual, we hope to set out some of the basic underlying phenomena, physical and societal, in a way that stimulates constructive discussions between students on a subject that is of interest and concern to so many of them. Because of the complexity of these systems, this is mainly a ‘know about’ chapter in a field where modelling and data complement each other – but the models are complex.
