Keeping the Earth system in a stable and resilient state, in order to safeguard Earth's life support systems while ensuring that Earth's benefits, risks and related responsibilities are equitably shared, constitutes the grand challenge for human development in the Anthropocene. Here, we describe a framework that the recently formed Earth Commission will use to define and quantify target ranges for a 'safe and just corridor' that meets these goals. Although 'safe' and 'just' Earth system targets are interrelated, we see safe as primarily referring to a stable Earth system and just targets as being associated with meeting human needs and reducing exposure to risks. To align safe and just dimensions, we propose to address the equity dimensions of each safe target for Earth system regulating systems and processes. The more stringent of the safe or just target ranges then defines the corridor. Identifying levers of social transformation aimed at meeting the safe and just targets and challenges associated with translating the corridor to actors at multiple scales present scope for future work.

The stability and resilience of the Earth system and human well-being are inseparably linked1–3, yet their interdependencies are generally under-recognized; consequently, they are often treated independently4,5. 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.

Air travel accounts for a major share of individual greenhouse gas emissions, particularly for people in high-income countries. Until recently, few have reduced flying because of climate concerns, but currently, a movement for staying on the ground is rising. Sweden has been a focal point for this movement, particularly during 2018–2019, when a flight tax was introduced, and air travel reduction was intensely discussed in the media. We performed semi-structured interviews with Swedish residents, focusing primarily on individuals who have reduced flying because of its climate impact. We explore how such individual transformation of air travel behavior comes about, and the phases and components of this process. Applying a framework of sustainability transformation, we identify incentives and barriers in personal and political spheres. We show that internalized knowledge about climate change and the impact of air travel is crucial for instigating behavioral change. Awareness evokes negative emotions leading to a personal tipping point where a decision to reduce or quit flying is made. However, the process is often counteracted by both personal values and political structures promoting air travel. Even individuals with a strong drive to reduce flying feel trapped in social practices, norms and infrastructures. Hence, we argue that personal and political spheres interact complexly and to reduce flying at larger scales, interventions are needed across spheres, e.g., change of norms, effective policy instruments and better alternatives to air travel.

Living within planetary limits requires attention to justice as biophysical boundaries are not inherently just. Through collaboration between natural and social scientists, the Earth Commission defines and operationalizes Earth system justice to ensure that boundaries reduce harm, increase well-being, and reflect substantive and procedural justice. Such stringent boundaries may also affect 'just access' to food, water, energy and infrastructure. We show how boundaries may need to be adjusted to reduce harm and increase access, and challenge inequality to ensure a safe and just future for people, other species and the planet. Earth system justice may enable living justly within boundaries.Rapid Earth system changes in the Anthropocene are harming nature and humans. The Anthropocene is also marked by increasing inequalities 1 and vulnerabilities 2 . Scientists have proposed planetary boundaries, such as climate targets, to reduce global environmental risks. Within the Earth Commission, we aim to propose 'safe and just Earth system boundaries' (ESBs) that go beyond planetary boundaries as they also include a justice perspective and suggest transformations to achieve them 3 . Safe and just ESBs aim to stabilize the Earth system, protect species and ecosystems and avoid tipping points, as well as minimize 'significant harm' to people while ensuring access to resources for a dignified life and escape from poverty. If justice is not considered, the biophysical limits may not be adequate to protect current generations from significant harm. However, strict biophysical limits, such as reducing emissions or setting aside land for nature, can, for example, reduce access to food and land for vulnerable people, and should be complemented by fair sharing and management of the remaining ecological space on Earth 4 . Behavioural experiments show that people contribute to common pool resource stewardship if they see the process and outcomes as just 5 . This perspective offers an approach to Earth system justice (ESJ) that can guide and operationalize the identification of 'just ends' in terms of Earth system boundaries (ESBs) and access indicators, and 'just means' in terms of sustainability transformations. It provides a discursive shift to reframe environmental science and policy to pay attention to distributive justice 6 .