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Current policies and actions make it very likely, at least temporarily, to overshoot the Paris climate targets of 1.5–<2.0 °C above pre-industrial levels. If this global warming range is exceeded, potential tipping elements such as the Greenland Ice Sheet and Amazon rainforest may be at increasing risk of crossing critical thresholds. This raises the question of how much this risk is amplified by increasing overshoot magnitude and duration. Here we investigate the danger for tipping under a range of temperature overshoot scenarios using a stylized network model of four interacting climate tipping elements. Our model analysis reveals that temporary overshoots can increase tipping risks by up to 72% compared with non-overshoot scenarios, even when the long-term equilibrium temperature stabilizes within the Paris range. Our results suggest that avoiding high-end climate risks is possible only for low-temperature overshoots and if long-term temperatures stabilize at or below today’s levels of global warming.Temporarily exceeding temperature targets could increase risk of crossing tipping-element thresholds. This study considers a range of overshoot scenarios in a stylized network model and shows that overshoots increase tipping risks by up to 72% compared with remaining within targets.

The stability and resilience of the Earth system and human well-being are inseparably linked 1 – 3 , yet their interdependencies are generally under-recognized; consequently, they are often treated independently 4 , 5 . Here, we use modelling and literature assessment to quantify safe and just Earth system boundaries (ESBs) for climate, the biosphere, water and nutrient cycles, and aerosols at global and subglobal scales. We propose ESBs for maintaining the resilience and stability of the Earth system (safe ESBs) and minimizing exposure to significant harm to humans from Earth system change (a necessary but not sufficient condition for justice) 4 . The stricter of the safe or just boundaries sets the integrated safe and just ESB. Our findings show that justice considerations constrain the integrated ESBs more than safety considerations for climate and atmospheric aerosol loading. Seven of eight globally quantified safe and just ESBs and at least two regional safe and just ESBs in over half of global land area are already exceeded. We propose that our assessment provides a quantitative foundation for safeguarding the global commons for all people now and into the future. We find that justice considerations constrain the integrated Earth system boundaries more than safety considerations for climate and atmospheric aerosol loading, and our assessment provides a foundation for safeguarding the global commons for all people.

Many scenarios for limiting global warming to 1.5°C assume planetary‐scale carbon dioxide removal sufficient to exceed anthropogenic emissions, resulting in radiative forcing falling and temperatures stabilizing. However, such removal technology may prove unfeasible for technical, environmental, political, or economic reasons, resulting in continuing greenhouse gas emissions from hard‐to‐mitigate sectors. This may lead to constant concentration scenarios, where net anthropogenic emissions remain non‐zero but small, and are roughly balanced by natural carbon sinks. Such a situation would keep atmospheric radiative forcing roughly constant. Fixed radiative forcing creates an equilibrium “committed” warming, captured in the concept of “equilibrium climate sensitivity.” This scenario is rarely analyzed as a potential extension to transient climate scenarios. Here, we aim to understand the planetary response to such fixed concentration commitments, with an emphasis on assessing the resulting likelihood of exceeding temperature thresholds that trigger climate tipping points. We explore transients followed by respective equilibrium committed warming initiated under low to high emission scenarios. We find that the likelihood of crossing the 1.5°C threshold and the 2.0°C threshold is 83% and 55%, respectively, if today's radiative forcing is maintained until achieving equilibrium global warming. Under the scenario that best matches current national commitments (RCP4.5), we estimate that in the transient stage, two tipping points will be crossed. If radiative forcing is then held fixed after the year 2100, a further six tipping point thresholds are crossed. Achieving a trajectory similar to RCP2.6 requires reaching net‐zero emissions rapidly, which would greatly reduce the likelihood of tipping events. Plain Language Summary The importance of reaching net‐zero greenhouse gas emissions to help avoid dangerous anthropogenic climate change is widely acknowledged. However, current national commitments do not align with this target and instead will lead to about 2.7°C warming by 2100. If the large‐scale carbon dioxide removal needed to reach net‐zero emissions is unfeasible and instead, the remaining hard‐to‐mitigate emissions approximately balance natural sinks, atmospheric greenhouse gas (GHG) concentrations will remain constant. Such fixed GHG levels will result in continued warming until the climate system reaches a state of radiative balance, which we call “committed warming.” We investigate the committed warming associated with the CO2 equivalent (CO2e) for each year for three emission scenarios. Critically, we then examine the probability of breaching tipping point thresholds at different levels of committed warming, finding that under the scenario that best matches current national commitments, we will be committed to crossing the critical temperature threshold for six key climate tipping points by 2100. Maintaining radiative forcing at only slightly elevated levels above present GHG concentrations will substantially alter parts of the Earth System through such “locked‐in” impacts. Society will only be able to avoid breaching tipping point thresholds through rapid and very substantial reduction of human emissions. Key Points We conduct a thought experiment on equilibrium global warming and tipping point likelihood under constant greenhouse gas concentration scenarios Maintaining radiative forcing at or above current levels would commit multiple parts of the climate system to passing tipping points Only a lower emissions scenario, which would require rapidly reaching net‐zero emissions, avoids crossing most climate tipping points

Tipping points characterize the situation when a system experiences abrupt, rapid, and sometimes irreversible changes in response to only a gradual change in environmental conditions. Given that such events are in most cases undesirable, numerous approaches have been proposed to identify if a system is approaching a tipping point. Such approaches have been termed early warning signals and represent a set of methods for identifying statistical changes in the underlying behaviour of a system across time or space that would be indicative of an approaching tipping point. Although the idea of early warnings for a class of tipping points is not new, in the last 2 decades, the topic has generated an enormous amount of interest, mainly theoretical. At the same time, the unprecedented amount of data originating from remote sensing systems, field measurements, surveys, and simulated data, coupled with innovative models and cutting-edge computing, has made possible the development of a multitude of tools and approaches for detecting tipping points in a variety of scientific fields. However, we miss a complete picture of where, how, and which early warnings have been used so far in real-world case studies. Here we review the literature of the last 20 years to show how the use of these indicators has spread from ecology and climate to many other disciplines. We document what metrics have been used; their success; and the field, system, and tipping points involved. We find that, despite acknowledged limitations and challenges, in the majority of the case studies we reviewed, the performance of most early warnings was positive in detecting tipping points. Overall, the generality of the approaches employed – the fact that most early warnings can in theory be observed in many dynamical systems – explains the continuous multitude and diversification in their application across scientific domains.

Continued anthropogenic pressures on the Earth system hold the potential to disrupt established circulation patterns in the ocean and atmosphere. In this narrative review, we investigate tipping points in these systems by assessing scientific evidence for feedbacks that may drive self-sustained change beyond critical forcing thresholds, drawing on insights from expert elicitation. The literature provides multiple strands of evidence for oceanic tipping points in the Atlantic Meridional Overturning Circulation (AMOC), the North Atlantic subpolar gyre (SPG), and the Antarctic Overturning Circulation, which may collapse under warmer and “fresher” (i.e. less salty) conditions. A slowdown or collapse of these oceanic circulations would have far-reaching consequences for the rest of the climate system and could lead to strong impacts on human societies and the biosphere. Among the atmospheric circulation systems considered, a few lines of evidence suggest the West African monsoon (WAM) as a tipping system. Its abrupt changes in the past have led to vastly different vegetation states of the Sahara (e.g. “green Sahara” states). Despite multiple potential sources of destabilization, evidence about tipping of the monsoon systems over South America and Asia is limited. Although theoretically possible, there is currently little indication for tipping points in tropical clouds or mid-latitude atmospheric circulations. Similarly, tipping towards a more extreme or persistent state of the El Niño–Southern Oscillation (ENSO) is currently not fully supported by models and observations. While the tipping thresholds for many of these systems are uncertain, tipping could have severe socio-environmental consequences. Stabilizing Earth's climate (along with minimizing other environmental pressures, such as aerosol pollution and ecosystem degradation) is critical for reducing the likelihood of reaching tipping points in the ocean–atmosphere system.

The Earth's oceans are one of the largest sinks in the Earth system for anthropogenic CO2 emissions, acting as a negative feedback on climate change. Earth system models project that climate change will lead to a weakening ocean carbon uptake rate as warm water holds less dissolved CO2 and as biological productivity declines. However, most Earth system models do not incorporate the impact of warming on bacterial remineralisation and rely on simplified representations of plankton ecology that do not resolve the potential impact of climate change on ecosystem structure or elemental stoichiometry. Here, we use a recently developed extension of the cGEnIE (carbon-centric Grid Enabled Integrated Earth system model), ecoGEnIE, featuring a trait-based scheme for plankton ecology (ECOGEM), and also incorporate cGEnIE's temperature-dependent remineralisation (TDR) scheme. This enables evaluation of the impact of both ecological dynamics and temperature-dependent remineralisation on particulate organic carbon (POC) export in response to climate change. We find that including TDR increases cumulative POC export relative to default runs due to increased nutrient recycling (+∼1.3 %), whereas ECOGEM decreases cumulative POC export by enabling a shift to smaller plankton classes (-∼0.9 %). However, interactions with carbonate chemistry cause opposite sign responses for the carbon sink in both cases: TDR leads to a smaller sink relative to default runs (-∼1.0 %), whereas ECOGEM leads to a larger sink (+∼0.2 %). Combining TDR and ECOGEM results in a net strengthening of POC export (+∼0.1 %) and a net reduction in carbon sink (-∼0.7 %) relative to default. These results illustrate the degree to which ecological dynamics and biodiversity modulate the strength of the biological pump, and demonstrate that Earth system models need to incorporate ecological complexity in order to resolve non-linear climate–biosphere feedbacks.

Several past episodes of rapid carbon cycle and climate change are hypothesised to be the result of the Earth system reaching a tipping point beyond which an abrupt transition to a new state occurs. At the Palaeocene–Eocene Thermal Maximum (PETM) at ∼56 Ma and at subsequent hyperthermal events, hypothesised tipping points involve the abrupt transfer of carbon from surface reservoirs to the atmosphere. Theory suggests that tipping points in complex dynamical systems should be preceded by critical slowing down of their dynamics, including increasing temporal autocorrelation and variability. However, reliably detecting these indicators in palaeorecords is challenging, with issues of data quality, false positives, and parameter selection potentially affecting reliability. Here we show that in a sufficiently long, high-resolution palaeorecord there is consistent evidence of destabilisation of the carbon cycle in the ∼1.5 Myr prior to the PETM, elevated carbon cycle and climate instability following both the PETM and Eocene Thermal Maximum 2 (ETM2), and different drivers of carbon cycle dynamics preceding the PETM and ETM2 events. Our results indicate a loss of “resilience” (weakened stabilising negative feedbacks and greater sensitivity to small shocks) in the carbon cycle before the PETM and in the carbon–climate system following it. This pre-PETM carbon cycle destabilisation may reflect gradual forcing by the contemporaneous North Atlantic Volcanic Province eruptions, with volcanism-driven warming potentially weakening the organic carbon burial feedback. Our results are consistent with but cannot prove the existence of a tipping point for abrupt carbon release, e.g. from methane hydrate or terrestrial organic carbon reservoirs, whereas we find no support for a tipping point in deep ocean temperature.

Humans are now operating well outside the planetary conditions under which social and economic development has been possible. A precondition for securing equitable access to this prosperity is to safeguard the stability of the Earth system. The situation is urgent—we need a swift and profound shift in direction—a collective transformation. In response, the Earth Commission has developed a science‐based framework that integrates biophysical limits with justice considerations, aiming to enable human wellbeing for all. The Earth Commission's first assessment showed that multiple safe and just Earth system boundaries have already been transgressed, threatening the resilience of the planet and the well‐being of billions. This paper outlines the vision and scientific strategy for the Earth Commission's second phase (2024–2027), which focuses on advancing this framework and translating it into actionable budgets and exploring transformation pathways toward a safe and just future. Key components include expanding the safe and just boundary assessment to currently under‐assessed Earth system processes (e.g., novel entities and ocean change), integrating justice more deeply into the framework, modeling interactions between boundaries and tipping points, and developing practical approaches to cross‐scale translation and transformation. Special attention is given to the structural inequalities and power dynamics that shape both environmental degradation and our capacity to act. Through coordinated research, interdisciplinary collaboration, and stakeholder engagement, the Earth Commission seeks to provide knowledge to guide collective efforts toward transforming to a safe and just space for both people and the planet. Plain Language Summary People around the world are already feeling the effects of a planet under pressure‐from climate change and biodiversity loss to rising inequality. Scientists are warning that we are pushing Earth's life‐support systems beyond their safe limits, putting both nature and human well‐being at serious risk. In response, the Earth Commission has created a new science‐based framework that brings together environmental limits and fairness. This helps define what a “safe and just” future looks like‐one where the planet remains stable, and the well‐being of all people is promoted. The next phase of work focuses on improving our understanding of under‐explored threats like pollution and novel types of pollution, deepening the role of justice in our analysis, and identifying fair ways to share responsibility for staying within Earth's limits. It also looks at how big changes to systems like energy and food can help move us toward a safe and just future. The goal is to support faster, fairer action that protects both people and the planet. Key Points Human activity has pushed the planet beyond safe and just limits, endangering stability and the well‐being of billions A just and rapid transformation is needed to shift toward a liveable future for both people and the planet The Earth Commission provides a science‐based framework to guide systemic change across scales and sectors

The concept of a “tipping point” is widely used to describe abrupt, potentially irreversible changes in complex systems - from climate subsystems to ecosystems and social dynamics. However, concerns have been raised about definitional ambiguity and conceptual overuse that may obscure rather than highlight potential systemic risk. Here, we offer a cross-disciplinary synthesis of the tipping point literature that identifies three essential properties—self-reinforcing feedbacks, threshold behavior, and persistence—as the defining characteristics of tipping dynamics. While different interpretations reflect genuine system-specific differences and offer complementary insights, these three properties help identify underlying patterns and causal mechanisms across diverse systems. This synthesis promotes conceptual clarity in how tipping point terminology is applied across diverse contexts. In doing so, we identify research priorities: moving beyond single-threshold models, developing cross-system early warning indicators, understanding cascading dynamics between interconnected systems, and advancing integrated models capturing climate-ecological-social feedbacks.Across diverse systems, tipping points are characterised by three key properties, namely self-reinforcing feedbacks, threshold behavior, and persistence, suggests a cross-disciplinary synthesis of the tipping point literature.

The Paris Agreement has seen the adoption of a 1.5° to 2 °C climate target, based on the belief that climate change becomes ‘dangerous’ above this level. Since then, the scientific community and the countries most affected by global warming have reiterated that the maximum limit to be reached should be 1.5 °C. This paper goes one step further by questioning the reasoning behind the adoption of these targets, arguing that the fossil fuel-dependent political context in which they were adopted has undermined justice concerns. We highlight the political influence of the fossil fuels industry within target-setting negotiations, analyzing the evolution of climate targets and fossil fuel lobbying. We then harness published scientific evidence and the Earth System Justice framework to analyze the impacts of the 1.5 °C target, and the injustices that have so far been implicitly deemed acceptable. We argue that 1 °C would have been a far more just target and was undermined by vested interests and status quo maintenance. Finally, we propose just supply-side policies to ensure an adequate placement of responsibility on the fossil fuel industry. This way we (a) identify political influences and scientific blind spots that have and could continue to hinder climate action, (b) reveal how these influences delayed more ambitious climate objectives, contributing to the adoption of an unjust climate target, and (c) promote a focus on supply-side measures and polluting industries in order to break free from the impasse in the energy transition and foster more just outcomes.