The authors break down the reasons for the United States to stay in the Paris Climate Agreement, arguing that the benefits far outweigh any potential costs. The Agreement gives the United States a seat at the table, and the ability to influence international policy on climate change, showing that the United States is open and willing to cooperate.

The author explores the role of the Montreal Protocol's assessment panel and draws lessons for the UNFCCC.

The authors explore, in particular, the implications for CO2 removal and solar geoengineering of the Paris Agreement's long-term temperature goals, provision for "removals by sinks," and market-based mitigation mechanisms.

Robert Stavins argues for an economic approach to solving environmental problems and explains why "environmental economics" is not an oxymoron.

The authors explore a novel approach to evaluating the ambition and fairness of countries' voluntary pledges to reduce emissions. This approach could facilitate negotiations at the upcoming UN climate conference in Lima—and the broader process leading to a new 2015 international climate agreement.

Joseph Aldy's Viewpoint makes a case for how transparency through policy surveillance can facilitate more effective international climate change policy architecture.

Forests can play a significant role in helping to avoid dangerous climate change, and a global agreement under the UNFCCC would be uniquely placed to support efforts in this regard. The rising global demand for agricultural and other land-based products means that pressures on land are increasingly cross-border, and there is an accelerating expansion of the deforestation frontier. Smart domestic policies are critical to solving the deforestation challenge, and recent private sector interest in "sustainable agriculture" is encouraging. However, global agreements that value standing forests and provide incentives that positively impact land use change decisions can be an equally important tool.

The United States has considerable tax administration and cap-and-trade expertise that could highlight potentially successful carbon pricing approaches. Although this experience is not climate-related, the United States deploys an efficient and highly compliant excise tax system, and it could assist developing country efforts to build their own capacity to tax carbon. The United States also has long experience with cap-and-trade systems for criteria air pollutants, much of which is transferable to greenhouse-gas emissions trading.

In December 2011, parties to the United Nations Framework Convention on Climate Change (UNFCCC) adopted the Durban Platform for Enhanced Action, which launched a new round of negotiations aimed at developing "a protocol, another legal instrument or an agreed outcome with legal force" for the post-2020 period. The Durban Platform negotiations got underway this year and are scheduled to conclude in 2015. This Viewpoint analyzes the elements of the Durban Platform and the possible role that a new instrument might play.

The Kyoto Protocol establishes a very complex and ambitious regime, in architecture if not stringency. The problem is that relatively few states, representing only about a quarter of the world's emissions, have been willing to assume emission targets under Kyoto....The future of the Protocol thus seems doubtful at best. Even in the most optimistic scenario, a new round of emissions targets couldn't be agreed in time to prevent a legal gap between the first and second commitment periods. A possible middle ground would be to establish a transitional regime that would be political in nature, but that could evolve over time into a legally-binding regime.