Having spent the last couple of months serialising the planetary boundaries, it would be remiss of me to end the series without looking at some common objections. The idea that we are in the ‘anthropocene’, the age in which humans are the dominant force on the planet, is a new one and not without opponents. Here are some of the common rebuttals and some notes on them.
Not all of the nine boundaries are really boundaries.
Some of the nine boundaries have a clear tipping point, and therefore a line in the sand that we can’t cross. The 350 ppm of CO2 is the most obvious. Others don’t have a biophysical threshold in that way, so some suggest that they aren’t really boundaries.
This argument has some legitimacy, as the initial report only identified tipping points for four of the nine boundaries. However, subsequent research has postulated a biodiversity tipping point, and another for freshwater systems. There may be tipping points for the other three that we haven’t found yet. But in some ways that’s missing the point. The boundaries are about a delineating a safe and healthy operating space for humanity, not just about defining the absolute limits of what we can do with the earth.
We can’t idealise the earth as it is. Other conditions might be better.
“The planetary boundaries hypothesis presupposes that the Holocene — the geological epoch spanning from the end of the last ice age to the Industrial Revolution – represents the most desirable state of the environment for human welfare” says a paper from the Breakthrough Institute, one of the more notable critiques.
Yes it does presuppose that, because there was no human civilization before the Holocene, and it is therefore “the only state that we know for certain can support the modern world we live in” as Johan Rockstrom says.
Just as importantly, any change to the earth’s systems will be hugely disruptive to our complex modern societies. There are many parts of the world where people are already struggling to adapt to a warmer climate, as rains fail, permafrost melts, and hurricanes grow more intense. Instability is a threat in itself, regardless of the direction of travel.
Many of these are local problems, not global ones
Many of the planetary boundaries are primarily local issues. Aerosol pollution may affect whole regions, but not the world. Marine dead zones are local, freshwater depletion might happen in one area but not in another. Is it fair to talk about these as global problems?
Climate change, ocean acidification and ozone depletion are global problems, although even those will have disproportionate causes and effects in different parts of the world. But many of the others have potential to become global. Push something too far, and it begins to affect ‘earth system functioning’, as the report puts it. Some of them can grow from local to regional problems. Others are cumulative. Some will never be technically global in scope, but they are global issues as far as society is concerned – things we should all be aware of and working together to find solutions to.
“Water, land, biodiversity loss, nitrogen and phosphorus all constitute “slow variables” in the Earth System” says Rockstrom. They don’t have global limits, but “tipping points at local and regional scales that add up to a global concern if they occur at the same time in multiple places on Earth.”
The boundaries concept is not solid enough to make policy
It’s all very well scientists drawing up limits for things – it’s the politicians that actually set the targets. And we might want to set different boundaries.
This is the price of writing environmental policy in a democracy. And it has a fairly poor record – see the EU consistently choosing a higher a bigger fishing quota than the science recommends, and predictably devastating its fish stocks by doing so. Or see ‘realist’ positions taken by climate negotiators who accept a political target rather than a scientific one, 550 or 450ppm rather than the tougher 350ppm.
Unless you live in a technocracy, this bargaining with the science will always happen, and the authors of the planetary boundaries don’t expect their work to be treated differently. “We sought to identify boundary positions beyond which we cannot exclude non-linear changes in one or several sub-systems on Earth” says Rockstrom. “It is up to societies to choose where the boundary position is placed.” The boundaries in the report apply the precautionary principle and set the bar at the lower end of the range.
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The work on the planetary boundaries is unfinished. The initial report was a starting point, and much has happened since. It’s also a starting point for discussion, a new way of framing the sustainability challenge, and it is already informing political debate and providing new language. The planetary boundaries are the most influential idea in sustainability to emerge in the six or seven years I’ve been writing about it, which is why I’ve given so much time to exploring them.
In case it’s useful to anyone, I plan to compile the recent series into a downloadable document. It’ll take me a while to get round to formatting and tweaking it, so I’ll let you know when it’s ready.
The Earthbound Report 
Jeremy,
Thanks for your thoughts. Definitely interested in having the whole series in a doc!