Print from Stockholm Resilience Centre
Think of an ecological regime shift like a stock market collapse: it is large, abrupt and heavy on the wallet. The collapse of Canada´s Newfoundland cod fishery in the early 1990s directly affected the livelihoods of some 35,000 fisherman and fish processing plant workers, and led to a decline of over $200 million dollars per annum in cod landing revenues.

However, there is one fundamental difference between the stock market and an ecological regime shift. Where stock markets usually bounce back, ecological regime shifts cause long-lasting changes to the ecosystem.

Furthermore, they are notoriously difficult to predict. They often come as a surprise, and by the time society realizes what is happening, it is often too late or too costly to reverse the changes. However, new research offers a glimmer of hope, arguing that changes in ecological time series (such as increased variability) can provide early warning of impending regime shifts.
Promising new indicators
In a PNAS-article entitled Turning back from the brink: Detecting an impending regime shift in time to avert it, centre-affiliated researcher Reinette “Oonsie" Biggs, Stephen R. Carpenter and William A. Brock investigated whether new early warning indicators of regime shifts can provide sufficient warning to take action to avert undesirable regime shifts.
- Work is underway to improve these new indicators and to test them in actual field settings. However, no one has yet answered the question of whether such indicators would provide sufficient warning to allow the implementation of management actions to avoid undesirable regime shifts, says Biggs.
Biggs, Carpenter and Brock used a fisheries food web model to investigate this question. They explored how close an ecosystem can get to an ecological threshold and still avert a regime shift by management changes being implemented. The model was also used to identify indicators that warning a before a “point of no return", where it is too late to take action to avert an undesirable regime shift.
Rapid response is essential
The results from the model showed that if the factor responsible for a regime shift can be rapidly altered (e.g. fishing pressure), it is possible to delay successful management action to avert a regime shift until the regime shift is underway. However, if the driver can only be manipulated gradually (e.g. shoreline habitat restoration) management action is needed substantially before a regime shift in order to avert it.
The challenge is that large increases in the indicators (which serve as warnings of an impending regime shift) only manifest themselves once a regime shift has been initiated. This means that the current indicators will only be useful in averting regime shifts if 1) the factor driving the regime shift can be rapidly manipulated, and 2) if management action is taken very rapidly as soon as the indicators start flashing their warning lights.
In cases where the factor driving the regime shift can only be gradually manipulated, the indicators will usually give warning too late to allow management action to avert the regime shift.
To improve their usefulness in averting ecological regime shifts, the researchers suggested that future research should focus on defining critical indicator levels at which management action should be taken, rather than detecting changes in the indicators.
More proactive decision-making processes needed
Averting ecological regime shifts does not simply require better indicators, but is also dependent on developing policy processes that enable society to respond more rapidly to warnings of impending regime shifts.

- Our results highlight that in systems subject to regime shifts there is often a discrete window for policy action, after which it becomes impossible to advert a shift, says Biggs. By the time adverse environmental effects become apparent it is often too late to avert a regime shift. Trial-and-error approaches that wait for evidence of negative environmental impacts before taking action are therefore ill-advised.
The results from the research underscore the need for developing decision-making approaches that enable proactive intervention in averting ecological regime shifts.

Source: Biggs, R., Carpenter, S.R., and Brock, W.A., 2008, Turning back from the brink: Detecting an impending regime shift in time to avert it. In PNAS  January 20, 2009   vol. 106  no. 3  826-831.

Sturle Hauge Simonsen
Date: 2009-01-23