Matt Ridley on the shift in emphasis for the Rio+20 conference:
The Riocrats now have a new tack, which will dominate next week’s discussion: planetary boundaries. An influential paper in 2009 written by Johan Rockstrom of Stockholm University and 28 colleagues argued that there are nine thresholds, crossing any of which will trigger collapse of the Earth’s life support systems: land-use change, loss of biodiversity, nitrogen and phosphorus levels, water use, ocean acidification, climate change, ozone depletion, aerosol loading and chemical pollution.
The trouble with this approach, according to a new report by Linus Blomqvist, Ted Nordhaus and Michael Shellenberger of the Breakthrough Institute in San Francisco, is that, for six of these measures, “there are no global tipping points beyond which these ecological processes will begin to function in fundamentally different ways. Hence the setting of boundaries for these mechanisms is an arbitrary exercise.”
A good example is land-use change. The Rockstrom paper suggested that if human beings convert 15% of the land surface of the Earth to cropland, the world will pass a tipping point, because as marginal land gets exhausted, a small increment in food demand would produce an accelerating increase in cultivation. Currently we cultivate about 11.7% of the land. Yet there is no evidence that anything special happens at 15%. In the words of Steve Bass of the International Institute for Environment and Development in London, “If anything, the opposite has probably been more true: Converting land for farming and for industry has clearly delivered a great deal of well-being.”
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The “boundaries” approach needs to incorporate the possibility that, thanks to technology, fossil fuels and minerals, people are already living more lightly on the land than we did in the past.
