ENGINEERING

Study of stockmarket crashes is helping scientists unearth the secret forces behind massive and sudden changes in climate and landscape. Dr Michael Raupach, an atmospheric researcher at the CSIRO Earth Observation Centre in Canberra, Australia is analyzing past abrupt changes, from ice ages to salinity, to try and identify the external forces that could cause present ecosystems and climate patterns to collapse. Dr Raupach will use examples of abrupt environmental change to demonstrate how external forces can affect systems and cause them to tip over critical thresholds when he speaks at the Sir Mark Oliphant International Conference on Thresholds and Pattern Dynamics in Perth on Monday. The conference is looking at threshold dynamics - the factors that lead up to the point where a complex ecological system like a forest or grassy savannah, or the global climate system, changes dramatically. An example is salinity, says Dr Raupach. "For a long time, while the saline groundwater is rising, you see nothing. But when it reaches the surface or root zone of plants and trees - the threshold - you see their sudden death across a wide area, due to a relatively subtle shift in the levels of the groundwater." Another example, he says, is the drought currently being experienced by eastern Australia. The subtle difference from past events is the interaction between drought and warming. While the current drought is similar in terms of lack of rainfall, the new feature this time is heat. It is by far the hottest drought on record, because of global warming. This is pushing many parts of the landscape, such as deep-rooted trees, beyond the point of no return. By identifying the external forces that cause these events, it may be possible to predict critical changes and either prevent them or manage the consequences, says Dr Raupach. The research uses well-known systems - like fire or a stockmarket crash - and analyses them to understand the causes. "These are familiar and so are excellent characterisations of what can go on in other systems," explains Dr Raupach. The research has uncovered hallmarks common to almost every complex system, says Dr Raupach. This means there are universal factors that can be used to analyse all systems. Dr Raupach's research asks four questions. Are there thresholds? How would things be different if we crossed the threshold? What drives the threshold? And can we manage the system to lower the possibility of bad outcomes? "One of the fundamental questions is: 'Can we identify what the crucial interactions are so we can get some idea of how likely this is?'," he explains. "We might be able to figure out how close we are to the threshold and determine the probability of tipping our climate into a different state." The research opens the way to better manage the human actions that do the greatest damage to the environment and natural ecosystems. "It means we are not completely powerless in influencing the trajectory of man-made climate change," says Dr Raupach. The 2005 Sir Mark Oliphant Conference on Thresholds and Pattern Dynamics takes place between July 3-7 at the University Club at the University of Western Australia.