Harmful tipping points in the natural world pose some of the gravest threats faced by humanity. Their triggering will severely damage our planet’s life-support systems and threaten the stability of our societies.
In the Summary Report:
• Narrative summary
• Global tipping points infographic
• Key messages
• Key Recommendations
Executive summary
• Section 1
• Section 2
• Section 3
• Section 4
This report is for all those concerned with tackling escalating Earth system change and mobilising transformative social change to alter that trajectory, achieve sustainability and promote social justice.
In this section:
• Foreword
• Introduction
• Key Concepts
• Approach
• References
Considers Earth system tipping points. These are reviewed and assessed across the three major domains of the cryosphere, biosphere and circulation of the oceans and atmosphere. We then consider the interactions and potential cascades of Earth system tipping points, followed by an assessment of early warning signals for Earth system tipping points.
Considers tipping point impacts. First we look at the human impacts of Earth system tipping points, then the potential couplings to negative tipping points in human systems. Next we assess the potential for cascading and compounding systemic risk, before considering the potential for early warning of impact tipping points.
Considers how to govern Earth system tipping points and their associated risks. We look at governance of mitigation, prevention and stabilisation then we focus on governance of impacts, including adaptation, vulnerability and loss and damage. Finally, we assess the need for knowledge generation at the science-policy interface.
Focuses on positive tipping points in technology, the economy and society. It provides a framework for understanding and acting on positive tipping points. We highlight illustrative case studies across energy, food and transport and mobility systems, with a focus on demand-side solutions (which have previously received limited attention).
Most of the current research has focused on understanding the tipping processes in different natural systems. Recent research on cascades has illustrated the role that they have in the emergence of different types of risks (Sillmann et al., 2022; Simpson et al., 2021). However, the role that cascades can play in tipping is less well understood, especially when they involve a combination of social and Earth system tipping points.. This section of the report identifies the following concerns that ought to be addressed in future research.
When identifying tipping cascades, it is necessary to identify clear boundaries of which systems are involved. This also involves establishing what are the system states and dynamics in order to identify how the tipping cascades alters them (i.e. a change in the reference condition of the system). For example, identifying differences between system states can be unclear, such as ‘fragmented’ vs ‘non-fragmented’ landscapes, or ‘forested’ vs ‘deforested’, which are continuums with easily recognisable end points but a hazy centre. This is particularly challenging in a social system, where identification of system state, dynamics and drivers of change is nascent and where observations over time are scarce.
It is also necessary to clarify whether cascades are identified within or across system boundaries. Furthermore, there are ambiguities regarding whether there is a threshold when a cascade emerges or stops and whether these can be identified.
It is also necessary to clarify the type of relationships between tipping cascades that relate to causality. For example, does the occurrence of a tipping point in a system (A) increase the likelihood of another system (B) tipping? Systems A and B may be far away in space and have different temporal scales. For example, non-linear relationships between phosphorus levels in shallow lakes and the growth rates of phytoplankton mean that, under certain conditions, small additions of phosphorus can lead to algal blooms and a rapid, hard-to-reverse deterioration in water quality (Scheffer, 2020; Scheffer et al., 1993; Carpenter et al., 1999). Declining water quality can cause a similarly non-linear or disproportionate response in the social and economic components of the freshwater social-ecological systems, for example through a rapid reduction in tourism revenue or property prices around a lake. Since management responses to removing phosphorus from the system, for example by limiting runoff from dairy farms upstream, are often slow to become effective, the initial ecological tipping point can trigger cascading effects through the broader social-ecological system (Schindler et al., 2016).