859. Six Out of Nine Planetary Boundaries are in Dangerous Territory

In 2009, Dr. Rockstrom's team at the Stockholm Resilience Center introduced the concept of planetary boundaries and identified nine critical processes that are crucial to the stability of the Earth system: climate change, biosphere integrity, biogeochemical cycles (nitrogen and phosphorus), ocean acidification, land use change, freshwater use, ozone depletion, atmospheric aerosol particles, and new chemical pollution. These have been established as the nine planetary boundaries. Scientists have attempted to quantify human-induced perturbations to these planetary boundaries and have defined a "Safe Operating Space" (SOS), which represents the region within which the Earth system can maintain its essential functions while ensuring human safety. By 2009, climate change, biodiversity, and the biogeochemical cycles of nitrogen were already considered to be at risk.

A recent article published September 13 in Science Advances found that six of these nine planetary boundaries have crossed into dangerous territory: climate change, biosphere integrity, biogeochemical cycles (nitrogen and phosphorus), land-use change, freshwater use, and emerging chemical pollution. Ocean acidification is on the verge of breaching its safe zone, while atmospheric aerosols have already crossed that threshold in certain regions. The situation continues to deteriorate in areas already beyond the safety zone.

The article emphasizes the interconnectedness of these boundaries within the Earth system, highlighting dynamic interactions and feedbacks across time and space. It emphasizes the need to consider the cumulative impacts of human activities on the Earth system as a holistic entity. Among these boundaries, the integrity of the biosphere stands out as particularly critical to Earth's stability and is closely linked to climate change. The paper advocates simultaneous efforts to mitigate global warming and preserve biosphere functions.

The article points to the significant role of global population growth since 1960 and the associated demand for food, fiber, and feed as drivers of land use change, resulting in biodiversity loss. It argues that while it is theoretically possible to support a world population of 10 billion people within planetary boundaries, achieving this goal will require significant changes. These changes should focus on reducing the environmental impacts of production and curbing resource demand, making it imperative to implement drastic measures to align with these sustainability goals.
 

Reference
Katherine Richardson, Earth beyond six of nine Planetary Boundaries, Science Advances (2023). DOI: 10.1126/sciadv.adh2458. www.science.org/doi/10.1126/sciadv.adh2458

Contributor: IIYAMA Miyuki (Information Program)