The Paris Agreement includes a call for countries to develop long-term GHG emissions reduction strategies. To inform long-term U.S. climate policy strategy while spurring global implementation momentum, the United States, jointly with Mexico and Canada, committed to complete in 2016 the U.S. Midcentury Strategy for Deep Decarbonization (MCS). The MCS report charts pathways to achieve at least 80 percent reductions in GHG emissions below 2005 levels by 2050 and includes the case for acting on climate; a summary of emissions trends; the vision for achieving deep GHG reductions by 2050, integrating action across the energy, land, and non-CO2 sectors, including close attention to the role of both natural and technological negative emissions; three deep-dive chapters on: decarbonizing the energy sector; storing carbon and reducing emissions on lands; and reducing non-CO2 emissions; and a discussion of U.S. action in global context.

The U.S.’ success in creating the MCS stems largely from the institutional arrangements in place and heavy public participation. Assembling a team with broad expertise, grounding the analysis in robust models, securing buy-in at the presidential level, and seeking interagency input and review throughout the process enabled the MCS to yield important insights for domestic policymaking.

The process of developing the strategy offers potential lessons for other countries as they author long-term strategies. Some lessons include:

• Countries must consider what sectors will be important in 2050, not just their relative importance today. For the United States, the land sector proved to be particularly crucial on the midcentury timescale. The MCS thus gave almost equal attention to the land and energy sectors and considered interactions between the two.
• Allow sufficient time to fully integrate expertise and analytic input from all relevant government agencies and to explore complex topics through deep dialogue with external experts.
• Avoid setting specific new near-term targets that are better established through the five-year NDC process under the Paris Agreement.