The idea of planet-wide environmental boundaries, beyond which humanity would go at its peril, is gaining ground
PULL a spring, let it go, and it will snap back into shape. Pull it further and yet further and it will go on springing back until, quite suddenly, it won’t. What was once a spring has become a useless piece of curly wire. And that, in a nutshell, is what many scientists worry may happen to the Earth if its systems are overstretched like those of an abused spring.
One result of this worry, in the autumn of 2009, was the idea of planetary boundaries. In the run-up to that year’s climate conference in Copenhagen a group of concerned scientists working under the auspices of the Stockholm Resilience Centre, in Sweden, defined, in a paper in Nature, what they thought of as a safe operating space for human development—a set of nine limits beyond which people should not push their planet.
The nine areas of concern were: climate change; ocean acidification; the thinning of the ozone layer; intervention in the nitrogen and phosphate cycles (crucial to plant growth); the conversion of wilderness to farms and cities; extinctions; the build up of chemical pollutants; and the level of particulate pollutants in the atmosphere. For seven of these areas the paper’s authors felt confident enough to put numbers on where the boundaries actually lay. For chemicals and particulates, they deferred judgment.
Since then, the idea of planetary boundaries has taken root. It crops up repeatedly in GEO-5, the United Nations Environment Programme’s new assessment of the world. The High-Level Panel on Global Sustainability, which reported recently to Ban Ki-moon, the UN’s secretary-general, gave the idea pride of place. And Planet Under Pressure, a big scientific conference held recently in London, made boundaries central to the message it sent to Rio+20, the UN environmental summit that opens in Brazil on June 20th.
Don’t fence me in
Planetary boundaries provide a useful way of thinking about environmental change, because in many cases they give scope for further change that has not already happened. That has brought the concept friends who are not normally persuaded by environmental thinking, as well as green enemies who will brook no compromise. But the concept has numerous drawbacks. The actual location of the boundaries is, as their proponents acknowledge, somewhat arbitrary. That is partly because of the incomplete state of current knowledge, but it may remain so however much anyone knows. Some boundaries might be transgressed without irreversible harm occurring. Some may have been drawn around the wrong things altogether. And some academic opinion holds that spectacular global change could come about without breaking through any of them.
The latest criticism comes from the Breakthrough Institute, a determinedly heterodox American think-tank that focuses on energy and the environment. Among the points made in a report it published on June 11th, two stand out. The first is that the idea of boundaries does not focus enough on the distinction between things with truly global effects and those that matter primarily at a local or regional level. The second is that the planetary-boundaries group derives most of its limits by looking at conditions during the Holocene—the epoch since the end of the most recent ice age, in which human civilisations have grown up. Both of these criticisms have merit.
via The Economist
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