For more than two decades, crafting global actions that all nations believe to be equitable has been a central challenge for international climate policy. Contentious debates over how to combat climatechange equitably, and how to equitably assess which countries are most responsible for taking action, has slowed progress toward a global climate agreement. As climate impacts mount, so does the urgency of resolving this challenge. Those least responsible for climate change are often the most vulnerable to changes in weather patterns, sea level rise, and other impacts, further exacerbating existing inequities. Meanwhile, actions—both to address climate impacts and to reduce emissions—are intertwined with broader equity issues involving livelihoods, health, food security, and energy access. The urgency of the equity challenge is heightened by recent negotiations for the new international climate agreement in 2015. Parties have determined that the agreement must be both “applicable to all Parties” and remain “under the Convention,” raising questions regarding equity that must be addressed by global leaders if the agreement is to build consensus and ambition (UNFCCC 2011).