There have been brief moments of reprieve in the drought that has stretched on since 2000 in the western United States—a water-rich 2011, a snow-laden 2019—but those breaks have only highlighted the more dramatic feature of the last few decades: unrelenting dryness.

Without human-driven climate change forcing Earth’s temperatures up, the ongoing drought would still be painful and parched. But it would be unexceptional in the grand scheme of the past 1,200 years. A new study in Nature Climate Change shows that Earth’s warming climate has made the western drought about 40 percent more severe, making it the region’s driest stretch since A.D. 800. And there’s a very strong chance the drought will continue through 2030.