This study quantifies the relative impact on future ocean acidification of different aspects of global climate change mitigation policies, such as the year that global emissions peak, how fast they reduce after their peak, and the long term minimum emissions that are possible. Relative to a scenario where emissions peak in 2016 and then decrease by 1% per year, further emissions reductions to 2, 3 and 4% per year lead to the same impact minimum pH (by 2100) if emissions peak 10, 15 and 17 years later respectively. Over the same time scale, non-mitigation scenarios lead to a decrease of global mean surface pH of 7.67 to 7.81. Strong and urgent mitigation, emissions peaking in 2016 and reducing by 5% per year, are shown to limit this minimum to 8.02. Minimum pH over longer timescales, the next 500 years, is largely determined by the minimum emission level that is attainable, owing to its relation with cumulative emissions.
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