Twenty years on, the success of the Montreal Protocol can help inform plans to mitigate climate change.
The revelation in 1985 that chemical emissions had ripped a vast hole in Earth's protective ozone layer sparked an international effort that has become one of the great environmental success stories. The Montreal Protocol, which came into force 20 years ago this year, halted the production of chlorofluorocarbons (CFCs) — the main culprits causing the hole above Antarctica — and set the schedule for phasing out most other ozone-destroying substances.
Today, stratospheric ozone levels are no longer in decline. And, although plenty of ozone-depleting chemicals remain in the atmosphere, there are signs of recovery in ozone levels at the mid-latitudes. The rapid and committed response of the world's nations has probably averted a future in which unfiltered sunlight would have scorched humans, animals and plants alike (see page 792).
Yet the Montreal Protocol is often written off as a model for curbing greenhouse-gas emissions. The international response to the ozone hole was fast — the protocol was ready for signing just two years after the hole was discovered — in part because the threat was immediate, and because chemical alternatives to CFCs had already been developed.
The situation is less clear cut for global warming — it is a slow-moving, long-term problem for which there is no single alternative to fossil-fuel use. Nonetheless, the Montreal model has much it can offer the fight against climate change. Governments are increasingly waking up to the urgency of the threat of global warming. And there is already an arsenal of alternative-energy technologies, ranging from wind turbines to energy-conserving building design, that could be delivered quite quickly around the world — if there was a political will to make it happen.
The Montreal Protocol's Multilateral Fund offers a particularly good model for such action. Industrialized nations, which have produced the majority of the world's CFCs, have contributed more than US$2 billion to the fund since it began operation in 1991 to help poorer nations meet their obligations under the treaty. Over time, this system has inspired a level of trust that is sorely lacking in today's global climate negotiations.
Above all, the Montreal Protocol serves as proof that the countries of the world can work together. And if nations, particularly those in the developed world, continue to take inspiration from its success, it could help divided governments find a common path towards tackling climate change.
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Lessons from Antarctica. Nature 460, 781 (2009). https://doi.org/10.1038/460781a