Is Earth’s climate in a state of 'termination shock'?

Cleaning up air pollution has saved millions of lives, but it has also given us an inadvertent taste of a nightmare climate scenario. The race is on to understand how bad it could be – and how to swerve the worst effects

Imagine the year is 2050 and the world has devised a way to stop global warming. No, not by doing the hard work of cutting greenhouse gas emissions, but by spraying reflective particles into the stratosphere that dim the sun. The strategy works: temperatures at ground level stabilise, and life goes on as normal despite escalating carbon dioxide concentrations in the atmosphere.

Until suddenly, something goes wrong. The spray guns break down, the money runs out, a pandemic hits or a global war disrupts operations. Whatever the case, the planet starts to heat up, fast, as years of pent-up emissions kick into effect. Ecosystems can’t cope, wildlife perishes en masse, societal chaos ensues.

This disastrous scenario and similar science fiction-sounding situations like it have been named “termination shocks” by climate scientists. But what most people don’t realise is that, over the past few years, we’ve been experiencing a version of it firsthand.

Global action to improve air quality – by shutting down coal-fired power stations and cleaning up shipping fuels – has saved millions of lives in recent decades. But on the flip side, air pollution can also cool the planet. Removing it has released a surge of warming that has warped the weather around the world.

Thanks to advances in climate modelling, we are now starting to understand the true impact of our drive for cleaner air on lightning storms, heatwaves and ocean ecosystems. What’s more, these changes could be a taster of what termination shocks of sci-fi proportions would look like. “It definitely provides a preview of what could happen,” says Tianle Yuan at NASA.

Cover photo:  Andrew Tsang Photography