President Obama and Chinese President Xi Jinping have both made ambitious pledges to combat climate change. Jinping pledged that China’s CO₂ emissions would peak around 2030; the first time that Beijing has set such a target. Obama promised that by 2025, the U.S. will have reduced its emissions by 23 to 26 percent from 2005 levels; twice as much as Washington had previously offered.

The carbon emission deal that has been reached between China and the United States is a promising breakthrough. The world’s biggest economies account for one-third of the planet’s emissions, so their initiative should help persuade other countries to reach a global emissions agreement at a United Nations climate summit next year in Paris.

President Obama faces opposition in the Republican-controlled Congress, though his aides say he can act unilaterally. Moreover, rapidly evolving energy conditions in the United States, from the increased supply of natural gas to the expansion of renewable energies, will ease the pain of carbon cuts.