Our planet is, first and foremost, a physical environment. The current challenge facing the geophysical sciences is not only to understand the systems that make up our planet – the atmosphere, the solid Earth and the oceans – but also to understand the processes that make it so dynamic, giving rise to weather, climate, ocean dynamics, earthquakes and other extreme phenomena. To observe, monitor, simulate and predict; to assess natural risks; and to contribute to public decision-making regarding the risks and impacts of natural phenomena.