Tipping points; bifurcations in realistic atmospheric models and data workshop

The notion of a "tipping point" has reached the popular parlance. However, there remains considerable skepticism among bona-fide climate scientists about whether realistic models of future climate exhibit such phenomena. Even the notion of what exactly a tipping point is is poorly defined. This workshop shall focus on the one hand on the mathematics and physics of tipping points, using the language of bifurcation theory in the presence of noise. Recent advances in this direction, for example by Thompson and Sieber have provided a way to test, directly from data, for the presence of bifurcations that might give rise to rapid, irreversible, changes in climate data. A canonical example is the Thermohaline Circulation (THC), which has been thoroughly examined over many years from the point of view of bifurcation theory, following the pioneering work of Dijkstra. However there is debate in the scientific community about whether such phenomena are artifacts of simple models which may not be present in more realistic simulations. Work by Valdes at Bristol on comparing climate models with historical data has however indicated that such simple models may in fact give a better qualitative description of observed periods of rapid changes. On a wider perspective there is the notion that a "tipping point" may be too simplistic a notion for policy makers. The prediction for example of "at what level of C02 (for example) will we reach the tipping point?" is the kind of question sought after by politicians, but may well not be a valid question.

This project received funding from the Cabot Institute's Open Call for funding.