featUre
of species and area of forest or pH levels of the ocean
Climate change and biosphere integrity
that regulate the stability of the Earth system.
The article suggests that two of these boundaries; climate
“For each process we have used scientific knowledge
change and biosphere integrity, are “core boundaries, which,
and global data to set thresholds for each of these pro-
if significantly altered, could drive the Earth system into a
cesses and variables beyond which we risk destabilising
new state.”
the Earth system,” Dr Reyers explains.
According to lead author, Professor Will Steffen from the
“Examples include 350ppm CO2 (climate change), 10
Stockholm Resilience Centre at Sweden’s Stockholm Univer-
species extinctions per million species per year (change
sity and the Australian National University in Canberra, such
in biosphere integrity) and 50 per cent forest cover
changes may damage efforts to reduce poverty and lead to a
(land system change). Each boundary is then set up-
deterioration of human well-being in many parts of the world.
stream of this threshold as an early warning sign, giving
“Past a certain threshold, curbing greenhouse gas emis-
us time to react before we hit the threshold.”
sions, biodiversity loss, or land-use change, for example, may
According to Dr Reyers, these nine Earth system pro-
not reverse or even slow the trends of the Earth system’s
cesses have been relatively unchanged over the past
degradation, with potentially catastrophic consequences,”
10 000 years, allowing our modern societies to develop
he says.
and thrive.
Dr Reyers adds: “From a South African or developing country
“But now there is evidence that we have pushed some
perspective, the important message about the planetary
of these processes close to the potential thresholds
boundaries is not that we must stop developing our econ-
of concern by changing the climate, reducing species
omies and societies, but rather that we need to carefully
numbers, through deforestation and by other activities
choose possible pathways that can deliver inclusive and
like adding pollutants to our water and air.
sustainable development within these boundaries.
“This has the potential to change the way the earth
“The current pathways of global development risk trans-
works, potentially making it a less hospitable place to
gressing these boundaries, which will reduce the options for
live in. Importantly, the article makes the point that we
fair and just pathways in future –especially in regions most
are no longer making these changes at local or regional
in need of development.”
scales, but at global scales,” she says.
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.” Living within planetary boundaries is the most promising strategy for ensuring a healthy future. Human prosperity need not cost the earth. Living sustainably is about doing more and better with less. It is about knowing that rising rates of natural resource use and the environmental impacts that occur are not a necessarily by-products of economic growth. *Reyhana Mahomed works for the CSIR.
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Public Sector Manager • June 2015