Q: Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.
Passage: The IPCC process on climate change and its efficiency and success has been compared with dealings with other environmental challenges (compare Ozone depletion and global warming). In case of the Ozone depletion global regulation based on the Montreal Protocol has been successful, in case of Climate Change, the Kyoto Protocol failed. The Ozone case was used to assess the efficiency of the IPCC process. The lockstep situation of the IPCC is having built a broad science consensus while states and governments still follow different, if not opposing goals. The underlying linear model of policy-making of more knowledge we have, the better the political response will be is being doubted. Question: What has successfully dealt with ozone depletion?
A:
the Montreal Protocol