Last month, California’s Gavin Newsom made headlines across the world when he sat down with Chinese President Xi Jinping in Beijing. Flashing a smile for the cameras and going in for a chummy handshake, the Democratic governor’s message was clear. “Divorce is not an option,” he later told reporters of the rocky relationship between the United States and its closest economic rival. “The only way we can solve our climate crisis is to continue our long standing cooperation with China.” Reducing dependence on fossil fuels, Newsom said, is among the most urgent items on the shared agenda of the two countries.

Together, the U.S. and China are responsible for more than a quarter of greenhouse gas emissions worldwide, and both countries need to take action to reduce their dependence on fossil fuels, as Newsom argued on his trip. One technology that most scientists agree will make a meaningful difference for the climate is solar panels. U.S. appetite for photovoltaics is growing, and although it’s the world's biggest polluter, China happens to dominate the global supply chain for solar panels: Chinese companies manufacture panels more efficiently and at greater scale than suppliers in other countries, and they sell them at rock-bottom prices.

But there’s a big problem at the start of the supply chain. Part of what makes China’s solar industry so prolific is that it is rooted in China’s Xinjiang province, home to a vast system of forced labor in detention camps and prisons where an estimated 1-2 million ethnic Uyghurs and members of other ethnic minority groups are held against their will. There is strong evidence that Uyghurs in Xinjiang live in conditions akin to slavery. Key components of solar energy, in other words, are being brought to much of the world by the victims of what U.S. authorities call an ongoing genocide.