and other local leaders just signed on to the new Resilient Communities for America Agreement (RC4A), pledging to invest in adaptation and urging state and federal leaders to support our local resilience initiatives and to take meaningful steps to build resilience and security throughout the nation. There are potential synergies between adaptation and mitigation, and these should be exploited. For example, the RC4A recognizes that investments in emissions reductions can avoid the costs of adapting to more severe climate impacts. But the focus is on hardening local infrastructure and preparing for more extreme events, not mitigation, especially not at the level of national policy or international agreements.Unfortunately, spending on sea walls, beach nourishment, hardening infrastructure, and other adaptation measures consumes resources that could be spent on mitigation. And adaptation doesnt do anything to capture the harmful externalities of greenhouse gas emissions by, for example, pricing carbon at its true cost. Without mitigation, incentives to invest in efficiency and renewable, low-carbon energy are weak. Worse, adaptation measures are likely to ease the pressure people feel to price greenhouse gas emissions or cut emissions through moral hazard and moral licensing effects. When people have subsidized flood insurance or believe the government will bail them out after a disaster, they are more likely to build in the danger zone and less willing to reduce their risk. Similarly, if people believe adaptation protects them from the risks of rising seas or more severe storms, they may be less willing to cut their personal carbon footprint or work for policies that would reduce emissions.But can we do it? Can we cut emissions? Can we create an energy system and economy that works, sustainably, for everyone? Technologically, the answer is yes. Those who say we dont have the technology, that clean, renewable energy is too expensive, that building a sustainable economy isnt possible. Efficiency, wind, solar and other renewable, low-carbon technologies are getting cheaper every day. Many actions to reduce emissions are profitable today, with ready-to-go, off-the-shelf technologies. If fossil fuel prices reflected the true costs of the emissions they create, then even more technologies for mitigation would be cost effective today.But can we build the public support for policies, from individual communities to the nation to the world as a whole, that will create incentives for innovation, speed the scale up of new technologies, and realize the potential for emissions reductions? Im constantly told its naive to keep working for mitigation, that theres no chance for national or international policy to cut emissions, that we will never get anything through the Congress and forget about agreements with China, India, and other developing nations.I say stranger and more amazing things have happened, and in my lifetime. During the Cold War, few people on either side believed they would live to see the Berlin Wall come down. And yet it fell. Few believed they would live to see the end of apartheid in South Africa. And yet it ended, peacefully. Few believed they would live to see an end to the violence in Northern Ireland. And yet there is