Exploring Tipping Points
For an activity associated with this concept try Tipping Points Activity . This activity guides students into developing their own case study of a tipping point in a graphic that has been documented by scientists.
· Systems can exist in alternative stable states or as equilibria between which there are tipping points.
· Destabilizing positive feedback mechanisms will drive systems toward these tipping points, whereas stabilizing negative feedback mechanisms will resist such changes.
A tipping point is the minimum amount of change within a system that will destabilize it, causing it to reach a new equilibrium or stable state.
I've used this video for quite a number of years but still find it engaging as a simpling introduction to the concept of tipping points. It was made by an art college student and it's a nice way to emphasise the interdisciplinary nature of the issues we are discussing. I first came across the animation in a workshop run by Jill Rutherford.
Once students have explored and understood feedback loops, they need to know how tipping points can occur in nature and how humans impact this. They also need to understand how the resilience of a system can affect the likelihood of a system moving into another alternative stable state via a tipping point. Some of the resources and ideas come from workshop participants.
A good place to start with tipping points is with the work done by the Stockholm Resilience Centre and Johan Rockstrom.
Laura Hamilton shared on the ESS Facebook group, a documentary she had found called Disruption. At around 32 minutes, Ricken Patel, founder of Avaaz, gives 3 great explanations of positive feedback loops in climate change.
More advanced reading:
In this article from Yale360, Jim Robbins explains how resilience is being used to plan conservation strategies for the impact of climate change. It's a nice easy read.
In this article published in 2015 in PLOS ONE, Rocha et al. look at the links between resilience and regime shifts.
In this article from Phys.org published in 2014 the links between fire, drought and tipping points in the Amazon are explored.
Gene Howson, a workshop participant in 2015 and recent graduate, introduced me to the Allee Effect which is a concept used in Biology, particularly population biology and has relevance to conservation biology. Gene explained that "the Allee Effect is an ecological parameter which follows the same general concepts of the 'tipping point' in that a ''at a particular moment in time, small change can have large, long-term consequences for a system'' (Lenton et al, 2008)."
Gene goes on to explain "When a certain species' population density, falls under a certain threshold the population has reached a tipping point whereupon, without rapid and direct human intervention, populations lose their resilience to continue to pass on their genes and therefore subject to often rapid extinction. He explains that it can be applied to natural predator-prey relationships (see case study on colonial guillemots (J Zu, 2010) to human induced collapse of Bluefin tuna populations worldwide, due to its value as a food source (Collette et al. 2011).
Gene speculates that only through conservation strategies have species like the giant panda, snow leopard and kiwi avoided extinction via the allee effect and species such as the North American passenger pigeon may have been succumbed to it.
Malcolm Gladwell has written about tipping points in mostly social systems and students may find this accessible but you need to be careful that they don't start using these examples rather than clear environmental examples. Here is a summary of his book.