Just before leaving office, the Trump administration sold the very first leases to drill for oil and gas in the coastal plain of Alaska’s Arctic National Wildlife Refuge–or ANWR. Any actual drilling, though, is still a long way off. Ecologists warn that even small disruptions in that area could accelerate climate change in unexpected ways. And those unexpected ways revolve around caribou herds. Oswalt Schmitz is a professor of population and community ecology at Yale’s School of Environment.