In their excellent 2006 book, Resilience Thinking, Brian Walker and David Salt talk about landscapes and communities being able to absorb disturbance without changing into a new state, or different regime. They mention the complexity of systems and how adaptable they must be in order to maintain their original characteristics or rebound from significant changes -- the resilience in the title. Basically, if the system is subjected to too many changes, and is not resilient, it can reach a threshold and cross it -- never to be the same again. A new stable state emerges, where the characteristics are different and, more important for socio-environmental systems, the processes on which people used to rely are different. The problem is, it is very hard to know what a threshold will be, and when a system is approaching it. Usually, one only finds out that the system has gone over a threshold when it happens -- and it is often too late or too hard to try to return things to "normal."
The book came to mind when I read the recent reports on the record reduction in Arctic sea ice this year. Reports (here and here) and blogs alerted to this new development and its role in the much discussed arena of climate change. A recent article put the whole thing into the resilience-and-thresholds perspective for me: According to scientists, we may be reaching a "tipping point" when it comes to sea ice, a point where the new state of the system itself will ensure that there is no return under the current conditions, i.e., less ice creating more water surface, which is darker, therefore absorbs more heat, exacerbating the warming even more, leading to more melting, and therefore no return to the historic levels of sea ice. And we are reaching it faster than models predicted.
That would be worrisome enough, given the implications of a reduced or non-existent sea ice shelf for nations, humans, biodiversity, and ecological systems. However, it becomes even more of a concern when we think that Arctic sea ice was recently listed as one of the tipping elements in the Earth's climate system. The authors list Arctic sea ice and other ice sheets together with other systems, such as the Amazon rainforest, that when changed past a certain point can alter the state of the Earth's climate system, and highlight the importance of early warning systems to determine when those elements are reaching that dangerous point of no return.
As mentioned before, usually one is only aware of a tipping point when it already happened; luckily, in the case of the Arctic sea ice, the signs are here, and action can be taken. However, the climate change mitigation machine is stalled, the climate debate continues, and to make matters even worse, the tipping point is apparently coming faster than previously predicted. Not only are we faced with the daunting task of trying to reduce proven Arctic sea ice melting, we are also running out of time. A tipping point is hitting us in the face, and it seems nothing will be done soon enough, while policy makers and the public at large continue to debate if global warming is really man-made, or if measures to reduce greenhouse gases will stall the economy. According to legend, the Emperor Nero fiddled while Rome burned. Is this how our descendents will view us? We are living in interesting times indeed.