standard Early warning signals for environmental and social change

Earth systems are known to switch suddenly without warning. Take the weather for example, where one moment it could be a bright, sunny day and the next it suddenly transforms into strong winds and heavy rain of a severe storm. In the case of climate modelling of the West Antarctic ice sheet, recent research has indicated that its potential collapse has already begun and that it has reached a critical stage of no return, no longer able to maintain its stability.

There are parallels in social systems as well, such as failures of highly interconnected banks precipitating a global financial crisis. Riots or standing ovations are also examples of social systems that exhibit tipping point behaviour. There are several things to consider about how early warning signals may be useful for understanding how physical and social systems valuable to society behave:

  • Finding ways to detect early warning signals that allow sufficient insight into the event in question in order to prepare for it in time.
  • The similarities and contrasts between early warning signals for social and physical systems.
  • Identifying clues to how systems, whether physical or social, demonstrate tipping point behaviour.

Physical scientists and mathematicians have defined ‘tipping point’ in a number of similar ways, including a small change that transforms the future state of the system, or a sudden flip from one state into another. Scientists use data from different kinds of earth systems, such as the Earth’s climate system or an ecosystem, to gain insight into what drives these kinds of change, including possible early warning signals. These signals could be used to identify whether the financial sector may be in store for a crisis, or when a critical number of the world’s population reduces its carbon footprint to offset the effects of climate change. These systems may give ‘hints’ or signs of slowing down before entering a critical phase.

Slowing down

An early warning signal can also be defined in a number of ways. In relation to climate change scientists refer to a ‘critical slowing down’ where the climate system could take longer and longer to return to its previous state, and inevitably fails to do so. A useful visual metaphor for this kind of change is called a ‘potential well’.

Think of a marble moving down a slope. As it travels further and further away it takes longer for it to return to its previous place and the further it travels from its former state the more unlikely it is to return. The ‘slowing down’, the increased amount of time it needs to return to its previous state, is the warning signal. The tipping point is the point of no return, when it can no longer go back.


Chart showing neo-glacial climatic cooling in the North Atlantic region. Figure adapted from Dahl-Jensen et al 1998, Science. DOI: 10.1126/science.282.5387.268

Climate flickering

In climate research a ‘flickering’ between different values in the system is seen before it approaches a large scale change that shifts it into a different state entirely, known as a bifurcation. Tipping Points researchers (WP1) have found evidence of this phenomenon in lake sediment cores using two climate proxies, chironomids (non-biting midges) and pollen grains. This flickering may have been an early warning signal for the pronounced Neoglacial cooling event that took place in the North Atlantic region 4,000 years ago.

Social scientists are also studying potential early warning signals in social systems, but the term is not nearly as common as it is in the physical sciences. While the illustration of a potential well may be useful for understanding early warning signals in physical systems, it should be used with caution if applied to social systems. In addition to understanding the physical phenomena that lead to critical changes in climate, it may also be useful to understand how evidence from scientific observations of the ways that environmental systems can “tip” into an altered state, influences how people respond to climate change. Without a thorough grasp of the ways people respond to representations of scientific information on climate, policy could also be stuck in a potential well if it doesn’t respond to feedback from the public.

Social feedback

In relation to climate change tipping points can impact human behaviour in a variety of ways. The task for social scientists is to find out how people’s perceptions of risk and uncertainty about climate change influences their behaviour. Getting people to act may not be so much about arguing for the scientific evidence of climate change, but tapping into their social networks and getting them to cooperate in order to achieve a common goal, such as carbon mitigation. If the use of climate science words in books are an indicator of people’s interest in climate science it appears to be going down. How can we communicate about such a crucial issue as climate in a way that gets people to act?

Since social systems clearly feedback into the climate system through carbon emissions then the connectivity of the system, the networks that lead to the spread of those kinds of behaviour, need to be identified. Otherwise it doesn’t matter how many times messages about climate change are transmitted, if it doesn’t affect the social networks that lead to changes in human behaviour, they will likely accomplish little. For getting people to act on climate change, it may come down to the issue of uncertainty.


A standing ovation is an example of emergent behaviour in a social system. Photo: NelC/Flickr

If people are uncertain about a situation they are unlikely to act upon it, but if others around them cooperate they could likely change their behaviour. Despite living in a ‘me first’ society centred on individual needs, values and consumption, our social connections (peer influence) are a prime influence on how we behave. Rarely do we act in isolation when making a decision, even simple ones. Take for example a standing ovation. After the end of a public performance such as a concert or play, the choice to stand up and clap is influenced by what people do around us. Whether they give a standing ovation or remain in their seat it will also influence the behaviour of people around them.

In the case of acting on climate change it is probably no different, but could be determined more by the influence of people’s social networks, or in the case of a standing ovation, simply the people in their immediate environment. If information on climate change doesn’t connect with people’s social networks they will likely fail to respond.

To really address the question of population responses to climate change it may be better to focus more on the social processes that drive human influence, including how people react to tipping behaviour in the climate system. In order to provoke effective social responses to climate change we need to ask: what are the tipping points for getting the global population to act on not only climate change but a wide range of other important issues to society?

References and Further Reading:

Bentley RA, Maddison EJ, Ranner PH, Bissell J, Caiado CCS, Bhatanacharoen P, Clark T, Botha M, Akinbami F, Hollow M, Michie R, Huntley B, Curtis SE and Garnett P (2014) Social tipping points and Earth systems dynamics. Front. Environ. Sci. 2:35. doi: 10.3389/fenvs.2014.00035 (free to read online)

Garnett, Philip (2012) ‘Going around again : modelling standing ovations with a flexible agent-based simulation framework.’, in Proceedings of the 2012 workshop on complex systems modelling and simulation. , pp. 27-46. CoSMoS. (free to read online)

This blog post is based on research from the Tipping Points project funded by the Leverhulme Trust.

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