THE EARTH SYSTEM: COMPLEXITY, SIMULATION AND PREDICTION

The objective of much traditional Geology has been to produce a narrative of planetary evolution. The shift from that paradigm to one in which we attempt to understand the Earth as a system is not a trivial one, it involves identifying and measuring high level indices of system behaviour that are the outcomes of complex interactions and developing the capacity to simulate them. Climate, atmospheric CO2 concentration, the Earth’s magnetic field are examples of high level indicators of system state that can be measured in time and space. The processes that influence the evolution of climate on all timescales for example, include geotectonism, biotic evolution, Earth orbital variations, ocean circulation etc. The system is strongly coupled, many components are non-linear so that its time variance spectrum cannot be explained by a single or simple series of forcings, and its simulation requires considerable computing capacity.

As this potential to understand the Earth in new ways has developed, so has the wider need for it. Humanity has now become a powerful geological agent, and has had impacts on the Earth system that have the capacity to effect its evolution, with potentially severe implications for humanity and the sustainability of our mode of life. Understanding the Earth system, using that understanding to mitigate damaging human impacts and finding strategies for sustainable use of the planet’s resources pose great challenges to science in analysing complexity and in modelling and forecasting. It is an onerous task, and requires collaborations to be forged between geologists, geophysicists, geochemists, biologists, climatologists, oceanographers, cosmologists, geomorphologists, engineers etc, and requires us to learn how to project our science effectively in the social and political domain.