Durban - Four of the nine “early warning lights” are flashing on the Earth’s dashboard, cautioning humanity that a multitude of environmental issues may require urgent attention.
This is the gist of a new research paper by 18 global scientists, including Stellenbosch-based Dr Belinda Reyers of the CSIR.
The paper was published this month in the international journal Science, generating renewed debate on the concept of planetary boundaries.
To use a crude analogy, the planetary boundaries concept has been likened to the warning lights on a car dashboard, providing early warnings that petrol is running low, the engine is overheating or that a speed limit has been exceeded.
“It is a bit like your car fuel light coming on – you still have some fuel left, but you had better take action soon,” said Reyers.
But what if, using this same analogy, it turns out the planet is running run of petrol?
“Well in that case,” said Reyers, “maybe it’s time to think about making a few tweaks to your engine or switching to biodiesel – or buying an electric car.”
The authors have acknowledged criticism that there are “zones of uncertainty” in making predictions about the precise point when environmental damage can be classified as potentially harmful to human societies.
Nevertheless, lead author Professor Will Steffen, of the Australian National University and Stockholm University, said the latest work was not intended as another doomsday report, but an attempt to define potential boundaries that should be approached with caution.
The report, which builds on an earlier work published in 2009, defines a wide range of nine planetary boundaries – and suggests that four of these boundaries appear to have been crossed, largely because of recent human development.
The four red lights they identify are:
* climate change
* biosphere integrity (including species extinctions and biodiversity loss)
* land-system change (such as deforestation)
* biogeochemical flows (high pollution levels from nitrogen and phosphorous fertilisers).
If pushed past these safety limits, the Earth could become “much less hospitable to the development of human societies”, they say.
Reyers, the only South African researcher in the project, said her work had focused on biological diversity and biosphere integrity as planetary boundaries.
A real challenge was how to measure changes in the diversity of life on Earth in a way that was relevant to human development. “At the moment all we have is species extinction rates,” she said.
While there was much information about the status of birds, mammals and frogs, this group of creatures made up less than 2% of all the species described by science. “There is much less information available on the extinction of plants, fungi or micro-organisms.”
Instead of measuring the extinction of charismatic animals such as the dodo or the quagga, her group examined the system-level impacts of lesser-known creatures.
“So it becomes less about the big names like lions and rhinos, but more about the roles of species – for example, how does the disappearance of vital pollinating species or seed-eaters impoverish the environment or how does the loss of large tree species reduce the capacity of the Earth to sequester carbon or mitigate climate change?”
The researchers propose that the early-warning boundaries be set at suitably “precautionary” levels to make room for some uncertainty and so there is time to respond and stay away from the thresholds.
“When it comes to extinction rates, for example, you should not set that early-warning light for when it is too late.
“The current species extinction lists of today are possibly a reflection of the situation 20 years ago.”
The full report was published in the January 16 issue of Science.
The Mercury