This April, for the first time ever, renewable energy supplied more power to America’s grid than coal. In two-thirds of the world, they’ve become the cheapest forms of power.

Solar and wind will power half the globe by 2050, based on BloombergNEF forecasts. By that time, coal and nuclear will have all but disappeared in the U.S., forced out by cheaper renewables and natural gas.

The market triumph of renewable energy marks the biggest victory yet in the fight against global warming. Solar and wind are proliferating not because of moral do-gooders but because they’re now the most profitable part of the power business in most of the world. An industry that once relied on subsidies is now increasingly standing on its own.

Electricity generation has traditionally been the world’s biggest source of greenhouse-gas emissions. In the U.S., for the first time since the 1970s, this is no longer the case. Since 2016, American power plants have given off less carbon dioxide than the nation’s transportation sector, where oil continues to dominate.

Solar, wind and hydropower resources combined generate more than a quarter of the world’s electricity. In China and India that share will surpass 60% by 2050, BNEF estimates show, and Europe will top 90%.