United States. A study by the Cooperative Institute for Research in Environmental Sciences (Cires) and the National Oceanic and Atmospheric Administration (Noaa) shows that the Montreal Protocol has significantly reduced U.S. climate-altering greenhouse gas emissions.
The research, the first to quantify the impact of the Montreal Protocol in the US on greenhouse gas emissions with atmospheric observations, shows that reducing the use of ozone-depleting substances from 2008 to 2014 eliminated the equivalent of 170 million tonnes of carbon dioxide (CO2) emissions each year. That's about 50 percent of the reductions achieved by the United States for CO2 and other greenhouse gases over the same period.
By 2025, scientists project that the effect of the Montreal Protocol will be to reduce U.S. greenhouse gas emissions by the equivalent of 500 million tons of CO2 per year compared to 2005 levels. This reduction would represent about 25-30 percent of the U.S. target committed during the United Nations climate meetings in Paris in 2015 (Council of the Parties or COP 21).
Previous studies have shown that the Montreal Protocol has been more effective at reducing global greenhouse gas emissions than any other international effort, even though climate change was not considered during the initial treaty negotiations in the late eighties.
Source: Cires.