Prime Minister Narendra Modi surprised delegates at the COP26 climate summit with a bold pledge: the world's third-biggest emitter will reach net-zero by 2070. The announcement injected new life into talks that had been set back by a disappointing outcome from the Group of 20 meeting in Rome this weekend. Though India's goal is two decades behind rich nations such as the U.S. and U.K., it's compatible with what scientists say is needed to avoid catastrophic global warming.