The concept of planetary boundaries was introduced to define safe limits for human activities within the Earth System to avoid abrupt environmental changes. The study identifies nine planetary boundaries, with seven quantified: climate change (atmospheric CO₂ concentration <350 ppm and/or radiative forcing change of +1 W m⁻²), ocean acidification (mean surface seawater saturation state with respect to aragonite ≥80% of pre-industrial levels), stratospheric ozone (O₃ concentration <5% reduction from pre-industrial levels), biogeochemical nitrogen cycle (industrial and agricultural fixation of N₂ ≤35 Tg N yr⁻¹), phosphorus cycle (annual P inflow to oceans not to exceed 10 times natural background weathering), global freshwater use (<4000 km³ yr⁻¹), and land system change (<15% of ice-free land under cropland). Two boundaries, chemical pollution and atmospheric aerosol loading, remain undefined. Humanity has already transgressed three boundaries: climate change, rate of biodiversity loss, and changes to the global nitrogen cycle. These boundaries are interdependent, and transgressing one may affect others. The study emphasizes the need for major advancements in Earth System and resilience science to fill knowledge gaps. The planetary boundaries concept provides a framework for shifting governance and management approaches toward estimating a safe space for human development. The boundaries define the "planetary playing field" for humanity to avoid major environmental change. The study highlights the importance of considering the resilience of societies and ecosystems in response to transgressions. The proposed boundaries are preliminary and subject to uncertainty, requiring further research to refine them. The study underscores the need for global cooperation and action to stay within these boundaries and ensure sustainable development.The concept of planetary boundaries was introduced to define safe limits for human activities within the Earth System to avoid abrupt environmental changes. The study identifies nine planetary boundaries, with seven quantified: climate change (atmospheric CO₂ concentration <350 ppm and/or radiative forcing change of +1 W m⁻²), ocean acidification (mean surface seawater saturation state with respect to aragonite ≥80% of pre-industrial levels), stratospheric ozone (O₃ concentration <5% reduction from pre-industrial levels), biogeochemical nitrogen cycle (industrial and agricultural fixation of N₂ ≤35 Tg N yr⁻¹), phosphorus cycle (annual P inflow to oceans not to exceed 10 times natural background weathering), global freshwater use (<4000 km³ yr⁻¹), and land system change (<15% of ice-free land under cropland). Two boundaries, chemical pollution and atmospheric aerosol loading, remain undefined. Humanity has already transgressed three boundaries: climate change, rate of biodiversity loss, and changes to the global nitrogen cycle. These boundaries are interdependent, and transgressing one may affect others. The study emphasizes the need for major advancements in Earth System and resilience science to fill knowledge gaps. The planetary boundaries concept provides a framework for shifting governance and management approaches toward estimating a safe space for human development. The boundaries define the "planetary playing field" for humanity to avoid major environmental change. The study highlights the importance of considering the resilience of societies and ecosystems in response to transgressions. The proposed boundaries are preliminary and subject to uncertainty, requiring further research to refine them. The study underscores the need for global cooperation and action to stay within these boundaries and ensure sustainable development.