2013 Academic Year Seminars
There is a possibility that the climate could undergo rapid and dramatic changes over the next century or so. It is believed that these abrupt changes have a low probability, but there is little evidence for what this probability could be. In this talk I discuss methods we could use for estimating these probabilities from deterministic climate models. These methods are based on the idea of an emulator. An emulator is a statistical approximation to the full deterministic climate model. The full climate model is expensive to run, so we are limited in the number of runs we can achieve. This means we cannot use Monte Carlo methods, for example. We run the climate model at a designed set of places and use these runs to build an emulator. This emulator can now be used instead of the full model since it takes an insignificant amount of computer time. Using the example of the collapse of the thermohaline circulation in the North Atlantic we illustrate these methods and show how they can be used to estimate the risk of low probability events.
After degrees in mathematics and statistics from the Universities of Exeter and Reading, Peter Challenor joined what was then the Institute of Oceanographic Sciences to work on the statistics of extremes. He has been there ever since although it is now known as the National Oceanography Centre. During his career Peter has been interested in extremes, wave climate and remote sensing of the ocean, his current main interests are in the analysis of computer experiments, in particular models of the climate system.