Four of nine planetary boundaries that underpin our life on Earth by making the planet a safe, stable and resilient place to live, have been crossed as a result of human activity. These findings have just been published in the journal Science (16 January 2015) by an international team of 18 researchers, including the CSIR’s Dr Belinda Reyers, a biodiversity scientist.

Planetary boundaries are based on global processes that relate to human-induced changes to the environment. The planetary boundaries concept, first introduced in 2009, proposes that these nine systems and processes regulate the stability of the Earth’s system – the interactions between land, ocean, atmosphere and life. If pushed beyond safe limits, the Earth may become less hospitable for humankind to prosper. In this update on the boundaries, the authors found that climate change, the loss of biosphere integrity (through species extinction, and the loss of genetic and functional diversity), land-system change (for example deforestation), and biochemical flows (for example phosphorus and nitrogen from fertilisers) have passed beyond safe levels.

The other five processes relate to ozone depletion in the stratosphere, ocean acidification, freshwater use, atmospheric aerosol loading (microscopic particles in the atmosphere that affect climate and living organisms) and the introduction of novel entities (such as radioactive or nanoparticles) into the atmosphere.

When researchers set the planetary boundaries, they looked at key biophysical processes or variables such as levels of carbon dioxide (CO2), nitrogen, numbers of species, area of forest or pH levels of the ocean that regulate the stability of the Earth system. “For each process we have used scientific knowledge and global data to set thresholds for each of these processes and variables beyond which we risk destabilising the Earth system,” Reyers explains. “Examples include 350ppm CO2 (climate change), 10 species extinctions per million species / year (change in biosphere integrity); 50% forest cover (land system change). Each boundary is then set upstream of this threshold as an early warning sign giving us time to react before we hit the threshold.”

According to Reyers, these nine Earth system processes have been relatively unchanged over the last 10 000 years, allowing our modern societies to develop and thrive. “But now there is evidence that we have pushed some of these processes close to the potential thresholds of concern by changing the climate, reducing species numbers, through deforestation and by other activities like adding pollutants to our water and air. This has the potential to change the way the earth works, potentially making it a less hospitable place to live. Importantly, the article makes the point that we are no longer making these changes at local or regional scales, but at global scales,” she says.

The article suggests that two of these boundaries, climate change and biosphere integrity, are “core boundaries, which, if significantly altered, could drive the Earth system into a new state”.

According to lead author, Professor Will Steffen from the Stockholm Resilience Centre at Sweden’s Stockholm University and the Australian National University in Canberra, such changes may damage efforts to reduce poverty and lead to a deterioration of human wellbeing in many parts of the world.

“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 the Earth system’s degradation, with potentially catastrophic consequences,” he says.

Reyers adds: “From a South African or developing country perspective, the important message about the planetary boundaries is not that we must stop developing our economies and societies, but rather that we need to carefully choose possible pathways that can deliver inclusive and sustainable development within these boundaries. The current pathways of global development risk transgressing these boundaries, which will reduce the options for fair and just pathways in future - especially in regions most in need of development.”

Her contribution to this paper was to share the advances being made in biodiversity science, in South Africa and elsewhere, to explore how the species and ecosystems, which make up our biosphere, contribute to keeping the Earth system in a safe operating space for humankind.

“Our work demonstrated the importance, not just of species numbers, which is what most people focus on, but also the functions of these species, their biomass, distribution, as well as their genetic code. All of these contribute to keeping the Earth system working, for example by cycling nutrients, water and other materials and regulating climate, while also keeping the Earth system resilient to future change.”

These findings will be presented at the World Economic Forum in Switzerland this week. Link to media more information: http://bit.ly/1wer8Ic

Media contact:
Aubrey Matsila  Tel: +27 12 841 2834, Cell :0765677397

About Dr Belinda Reyers
Dr Belinda Reyers is a biodiversity scientist whose research focuses on the links between ecosystems and social systems with a focus on the relationship between nature and social development and poverty alleviation, as well as the implications of global change for this relationship. She is also a senior research fellow at the Stockholm Resilience Centre, Stockholm University, Sweden; and Vice Chair of the advisory science committee of the international platform on global change and sustainability: 
Contact details for Dr Belinda Reyers: Tel: +27 21 888 2488
Fax: +27 21 888 2684 
Email: breyers@csir.co.za