CEEDS member Paul Young and colleagues from the UK, New Zealand and the USA recently published an article in Nature on the climate impact of the Montreal Protocol. They demonstrated that by protecting the ozone layer, the Montreal Protocol avoided high UV levels which would have damaged the world’s vegetation and therefore limited its ability to act as a carbon sink.
In their model simulations, they found that a world without the Montreal Protocol would be 2.5°C warmer by 2100 compared to a world where it was enacted and the ozone layer recovers. Of this 2.5°C warming, 1.7°C comes from the fact that the ozone depleting substances the Montreal Protocol controls are also greenhouse gases. Newly quantified in their study is the additional 0.8°C that comes from the extra CO2 in the atmosphere that results from the reduced ability of the UV-damaged plants to take up carbon from the atmosphere.