A Safe Climate Means Cooling the Planet Featured

Climate risks are accelerating as warming approaches dangerous tipping points. This paper argues that restoring a safe climate requires a three-part strategy: rapidly reducing emissions, removing atmospheric carbon, and investigating ways to actively cool the planet.

The paper argues that the climate crisis has moved beyond a point where emissions reduction alone can provide climate safety. At around 1.5°C of warming, tipping points are already being triggered or approached, while existing greenhouse gas concentrations commit the Earth system to further warming. The appropriate goal, it argues, is therefore not simply limiting future warming, but restoring conditions closer to the relatively stable Holocene climate, including ultimately drawing atmospheric CO₂ back towards the pre-industrial level of around 280 ppm.

To achieve this, the paper proposes a “reduce, remove and repair” framework: eliminate greenhouse gas emissions at emergency speed; remove excess atmospheric carbon through natural and technological approaches; and urgently research interventions capable of temporarily cooling the planet and protecting critical Earth systems while emissions reductions and carbon drawdown take effect. It examines carbon removal options and sunlight-reflection approaches, including marine cloud brightening and stratospheric aerosol injection, while acknowledging their uncertainties and potential risks.
The paper concludes that climate intervention should be assessed not against today’s climate, but against the risks of allowing the world to become significantly hotter. With emissions cuts unable to halt near-term warming and carbon removal necessarily slow, it argues that safely cooling the planet must now be investigated as part of an emergency response aimed at avoiding irreversible tipping points and ultimately restoring a safe climate.