Wed 14 Nov 2018 06.00 GMT
Climate breakdown could be rapid and unpredictable. We can no longer tinker around the edges and hope minor changes will avert collapse
‘Tipping points are likely to remain invisible until we have passed them. We could see changes of state so abrupt and profound that no continuity can be safely assumed.’ Illustration: Ben Jennings
It was a moment of the kind that changes lives. At a press conference held by climate activists Extinction Rebellion last week, two of us journalists pressed the organisers on whether their aims were realistic. They have called, for example, for UK carbon emissions to be reduced to net zero by 2025. Wouldn’t it be better, we asked, to pursue some intermediate aims?
A young woman called Lizia Woolf stepped forward. She hadn’t spoken before, but the passion, grief and fury of her response was utterly compelling. “What is it that you are asking me as a 20-year-old to face and to accept about my future and my life? … This is an emergency. We are facing extinction. When you ask questions like that, what is it you want me to feel?” We had no answer.
Softer aims might be politically realistic, but they are physically unrealistic. Only shifts commensurate with the scale of our existential crises have any prospect of averting them. Hopeless realism, tinkering at the edges of the problem, got us into this mess. It will not get us out.
Public figures talk and act as if environmental change will be linear and gradual. But the Earth’s systems are highly complex, and complex systems do not respond to pressure in linear ways. When these systems interact (because the world’s atmosphere, oceans, land surface and lifeforms do not sit placidly within the boxes that make study more convenient), their reactions to change become highly unpredictable. Small perturbations can ramify wildly. Tipping points are likely to remain invisible until we have passed them. We could see changes of state so abrupt and profound that no continuity can be safely assumed.
Only one of the many life support systems on which we depend – soils, aquifers, rainfall, ice, the pattern of winds and currents, pollinators, biological abundance and diversity – need fail for everything to slide. For example, when Arctic sea ice melts beyond a certain point, the positive feedbacks this triggers (such as darker water absorbing more heat, melting permafrost releasing methane, shifts in the polar vortex) could render runaway climate breakdown unstoppable. When the Younger Dryas period ended 11,600 years ago, temperatures rose 10C within a decade.
I don’t believe such a collapse is yet inevitable, or that a commensurate response is either technically or economically impossible. When the US joined the second world war in 1941, it replaced a civilian economy with a military economy within months. As Jack Doyle records in his book Taken for a Ride, “In one year, General Motors developed, tooled and completely built from scratch 1,000 Avenger and 1,000 Wildcat aircraft … Barely a year after Pontiac received a navy contract to build anti-shipping missiles, the company began delivering the completed product to carrier squadrons around the world.” And this was before advanced information technology made everything faster.