by David Spratt
This article appears as the concluding section of Collision Course: 3 degrees of warming & humanity's future, recently published by Breakthrough.
“The problem is that the status quo is a suicide. Those (Paris) commitments, even if fully met, would lead to an increase in temperature […] above 3 degrees which would mean a catastrophic situation.”
— UN Secretary-General Antonio Guterres, May 2019
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In 2005 James Hansen, sometimes dubbed the “godfather” of modern climate research, warned that humanity was “on the precipice of climate system tipping points beyond which there is no redemption”. Nineteen years later, we are heading for eye-watering social and ecological disruption, and civilisational collapse. Cities and regions and nations will drown and desertify. There will be an unrelenting global food crisis. Billions will be displaced and the global economic and governance systems of contemporary society will not work.
In practical terms, the world has reached 1.5°C of global heating, the rate of warming is accelerating and will likely continue on that path for several decades, especially given the failure so far to bend the emissions curve down fast. That means 2°C by 2040 or shortly after, and the emergence of vast zones of unlivable heat two decades after that on the present course of grossly inadequate action. Tipping points have been passed or are close at hand for some of the biggest elements of the climate system, including polar ice sheets and vast forest and permafrost carbon stores; and system inertia and hysteresis make preserving and restoring those systems very challenging. Scientists are increasingly alarmed that we may be heading towards AMOC collapse by mid-century.
