Planetary boundaries or opportunities?

London: In the morning, I leave my house in the inner-London borough of Lewisham (‘Levesham‘ is the Saxon for ‘dwelling in the meadows’) and walk over the covered river Quaggy (from ‘quagmire’ or watery bog’) to cross the busy main road of Loampit Vale (‘good soils digging spot in a wide river valley’). Only the names bear any sign of this once rural area. Brick factories carved up the sides of Loampit Vale in the 1800s. My bog-standard Victorian terrace was built in the 1880s out of bricks cut from the hill on which it stands.

One hundred years later, another huge building transformation was underway. I take the Docklands Light Railway, a once-futuristic fully automated driverless train, remembering the excitement of my first journey on it 25 years ago. The boxy 80s designed cars take us into another utterly transformed landscape – within my lifetime – whose former use is also knowable only through the signs: West India Quay, Custom House…

The Planet Under Pressure conference this week in London’s glass and steel towered Docklands recognises that Earth has undergone a dramatic and recent change, and that humans are now the dominant biophysical force across the planet. We’re now in the Anthropocene rather than the Holocene. Humans are pushing global temperatures, land and water use beyond what we’ve experienced before. We’re polluting the biosphere, acidifying the oceans, and reducing biodiversity. At the same time, we are a global population of 7 billion – going on 9 billion – all of whom need food water, clean air and who lead increasingly complex lives requiring more things to be comfortable.

Nearly 3,000 experts in earth systems science and sustainability issues have gathered here to try and find a way through the mess and plan some sort of solution for future earth.

In 2009, Johan Rockström of the Stockholm Resilience Centre, and colleagues, identified nine “planetary boundaries” – biophysical thresholds – that must be observed if humanity was to remain in the “safe operating space” of Holocene-like conditions. Many scientists (and non scientists) agree with these thresholds – many unquestioningly – and indeed an entire book has been written based on these thresholds.

However, others argue that these nine are rather arbitrary choices. I would question whether, for example, we can be said to have a “climate change” boundary – surely it should be temperature or forcing? – or a “change in land use” or “biodiversity loss” boundary. Others contest that there are either no biophysical thresholds for these, or that we are far from reaching them.  I would disagree with this – there is a clear threshold for dangerous loss of stratospheric ozone, for example, and I would also say for global temperature – caused by too many greenhouse gas molecules and too few sinks – although whether that’s a 2, 3, 4 degree threshold, I’m not sure. I wouldn’t like to go above 2.5, but we are already heading beyond that, so what does that mean – are we all doomed? Possibly.

Now, Ruth Defries, Erle Ellis and some of the authors of the Planetary Boundaries paper, including Diana Liverman, are publishing another paper, describing Planetary Opportunities. “Scientists’ most useful role is not to set doomsday limits and set thresholds, but to provide a more optimistic opportunity for society,” Ellis told me. “There is no hard-line carrying capacity for the planet. Humans are very adaptive.”

Urbanisation is a good example of the human system responding to a planetary opportunity, Ellis says, by living more efficiently in larger populations, while freeing up rural land for ecosystem services or agriculture. We need to apply human ingenuity on a multi-scale approach – from individuals to the global, both in governance and the scale of scientific analyses – in order to find solutions, he says, citing examples of societies successfully adapting to environmental threats in the past. “Planetary boundaries are not a useful concept for society,” Erle says.

Wow, sounds like a big schism from the 2009 paper. But according to Defries, the new paper “does not represent a dispute among factions within the global change science community. It’s more an attempt to move forward with the discussion”.

I took the paper over to Rockström, and asked what he thought. “We should not frame this crisis as an opportunity. This is not an opportunity. If we destroy the water supply, the air, the climate, humanity will not be safe,” he says, adding that he finds the whole ‘technology-will-solve-all-our-problems camp tiresome. “But, the journey towards something good represents an opportunity. The safe operating space is an opportunity,” he concedes.

We are already in the Anthropocene – in that humans are the largest driver of planetary change – but we have not yet changed state from stable Holocene to another stable state yet, he says. Breaching tipping points could send us into another state of which we have no experience, and which is likely to be dangerous. Exceeding the planetary boundaries, as we already have for three of the nine, he warns, is a very dangerous game.

Perhaps the truth is that thresholds do exist, even if we can only recognise them with hindsight, but that our poorly adapted human brains cannot act on this message. The promise and language of opportunities may spur us to action – thus realising the truest opportunity.