The photograph on the mining conglomerate’s social media account showed 70 ethnic Uyghur workers standing at attention under the flag of the People’s Republic of China. It was March 2020 and the recruits would soon undergo training in management, etiquette and "loving the party and the country,” their new employer, the Xinjiang Nonferrous Metal Industry Group, announced.

But this was no ordinary worker orientation. It was the kind of program that human rights groups and U.S. officials consider a red flag for forced labor in China’s western Xinjiang region, where the Communist authorities have detained or imprisoned more than 1 million Uyghurs, ethnic Kazakhs and members of other largely Muslim minorities.

The scene also represents a potential problem for the global effort to fight climate change.