Updated planetary boundaries framework shows four of nine boundaries now crossed

Source: Steffen et. al., 16 January 2015, Science.
Four of nine planetary boundaries have now been crossed as a result of human activity, says an international team of 18 researchers in the journal Science (16 January). The four are: climate change, loss of biosphere integrity, land-system change, altered biogeochemical cycles (phosphorus and nitrogen).

The scientists say that two of these, climate change and biosphere integrity, are “core boundaries”. Significantly altering either of these “core boundaries” would “drive the Earth System into a new state”.

“Transgressing a boundary increases the risk that human activities could inadvertently drive the Earth System into a much less hospitable state, damaging efforts to reduce poverty and leading to a deterioration of human wellbeing in many parts of the world, including wealthy countries. In this new analysis we have improved our quantification of where these risks lie,” says lead author, Professor Will Steffen from the Stockholm Resilience Centre, at Stockholm University and the Australian National University, Canberra.

The planetary boundaries concept, first published in 2009, identifies nine global priorities relating to human-induced changes to the environment. The science shows that these nine processes and systems regulate the stability and resilience of the Earth System – the interactions of land, ocean, atmosphere and life that together provide  conditions upon which our societies depend.

Nine planetary boundaries
  1. Climate change
  2. Change in biosphere integrity (biodiversity loss and species extinction)
  3. Stratospheric ozone depletion
  4. Ocean acidification
  5. Biogeochemical flows (phosphorus and nitrogen cycles)
  6. Land-system change (for example deforestation)
  7. Freshwater use
  8. Atmospheric aerosol loading (microscopic particles in the atmosphere that affect climate and living organisms)
  9. Introduction of novel entities (e.g. organic pollutants, radioactive materials, nanomaterials, and micro-plastics).

Managing these priorities at safe global levels will enable world development within a safe operating space on Earth, say the researchers. The new research builds on a large number of scientific publications critically assessing and improving the planetary boundaries research since its original publication. It confirms the original set of boundaries and provides updated analysis and quantification for several of them, including phosphorus and nitrogen cycles, land-system change, freshwater use and biosphere integrity. Biosphere integrity relates to the scale and impact of humans on  ecosystems.

As human activity pushes the Earth System beyond planetary boundaries and into zones of increasing risk, marine ecosystems may change dramatically as a result of ocean acidification and eutrophication, or temperatures may rise so high as to pose significant threats to agricultural production, infrastructure and human health. The paper reports that continuing degradation of biosphere integrity will likely further erode the provision of ecosystem services on which human societies depend.

“Past a certain threshold, curbing greenhouse gas emissions, biodiversity loss, or land-use change, for example, may not reverse or even slow the trends of Earth System degradation, with potentially catastrophic consequences,” said Professor Steffen.

“Planetary Boundaries do not dictate how human societies should develop but they can aid decision-makers by defining a safe operating space for humanity,” says co-author Katherine Richardson from the Center for Macroecology, Evolution and Climate, University of Copenhagen.

This week, co-author Professor Johan Rockström, director of the Stockholm Resilience Centre, and co-Chair of the Transition Team of Future Earth, will present the new findings at the World Economic Forum. “In the last four years we have worked closely with policymakers, industry and organisations like WWF to explore how the planetary boundaries approach can be used as a framework for sectors of societies to reduce risk while developing sustainably.”

“It is obvious that different societies over time have contributed very differently to the current state of the earth. The world has a tremendous opportunity this year to address global risks, and do it more equitably. In September, nations will agree the UN’s Sustainable Development Goals. With the right ambition, this could create the conditions for long-term human prosperity within planetary boundaries,” he said.

Eight of the nine planetary boundaries have been quantified.

With climate change, for example, the team argue that carbon dioxide levels should not cross 350 parts per million (ppm) in the atmosphere. “This boundary is consistent with a stabilisation of global temperatures at about 1.5 degrees Celsius above pre-industrial levels,” said Professor Rockström.

Atmospheric concentrations of carbon dioxide are currently about 399ppm (December 2014) and growing at about 3ppm per year.

In order to respond to these changes, there is a need for "truly global evidence base", reports the paper. International research initiatives such as Future Earth respond to this need by advancing the generation of integrated knowledge to explore options for transformations towards sustainability. The paper's authors include Belinda Reyers, Vice-Chair of the Future Earth Science Committee.

The planetary boundaries research coincides with a second analysis developed by IGBP in collaboration with the Stockholm Resilience Centre, led by Professor Will Steffen, that charts “The Great Acceleration” in human activity since 1950. The paper, “The trajectory of the Anthropocene: the Great Acceleration”, reassesses and updates the Great Acceleration indicators, first published in the IGBP synthesis, Global Change and the Earth System, in 2004.

The assessment concludes that the global economic system is the prime driver of change of key components of the Earth System, supporting the need for a precautionary approach to transgressing planetary boundaries.