In September, President Joe Biden strengthened his standing as the most climate-ambitious president in our history. In a brave move, Biden canceled each and every oil- and gas-drilling lease in the Arctic National Wildlife Refuge—a response to Donald Trump’s illegal approval of leases there in the waning days of his administration.

It was a game-changing decision that will go a long way toward protecting Alaskan landscapes, Alaska Natives’ traditional ways of life, and the climate. But canceling leases is one thing; permanently protecting the Arctic’s ancient lands and waters is another. To do that, we need far more action from this administration.

It’s hard to understand just how big the Arctic Refuge is if you haven’t been there. At more than 19 million acres, it’s the largest wildlife refuge in the country. Its lands and waters, from rolling hills to vast plains to snowcapped mountains, have been left largely untouched by industry. I was left in awe upon experiencing just a tiny portion of this amazing place last summer. The majestic beauty of the refuge has left an indelible mark on my mind. The freedom from oil and gas extraction has allowed these landscapes to support wildlife and Alaska Native communities like the Gwich’in people since time immemorial. But oil companies are ready to destroy all this to pad their bottom lines.

That’s been Big Oil’s dream for decades—to replace the herds of Porcupine caribou with pumpjacks. As far back as the 1970s, supporters of Big Oil in Congress have had their sights on the Arctic Refuge. And for decades, the Gwich’in and their allies, including the Sierra Club, have worked to preserve those landscapes. With Biden’s cancelation of leases in the refuge, we won a major battle—though not a permanent one—in that struggle.

The truth is, we can’t stop now. Biden’s cancelations will last for the length of his administration, but they could be undone by a future Republican administration. Right now, leading Republicans are calling to not just restore those leases but to open up even more Arctic lands for oil and gas drilling. Combine that with the environmental and climate consequences of Biden’s misguided approval for ConocoPhillips’s Willow project on the North Slope and the situation facing the Arctic could go from cautiously optimistic to catastrophic overnight.

What we need are stronger protections that ensure the lands and waters of the Arctic are preserved for generations to come. The Biden administration has several immediate opportunities to help achieve that. The Department of the Interior can use the regular environmental impact statements that determine the management of the Arctic Refuge to limit the acreage open to oil and gas leasing to the smallest amount allowed. The agency can also develop a new administrative rule phasing out drilling in the Western Arctic, another reserve of millions of acres of public lands. Protecting these areas would not only preserve lands, wildlife, and Alaska Native communities but also get us much closer to achieving the goal of protecting 30 percent of all lands and waters by 2030.

To its credit, the Biden administration has taken promising steps, but the real, and necessary, goal remains unchanged and unfulfilled: ending all new oil and gas leasing in the Arctic. The White House has flirted with this, from the lease cancelations to making the Arctic Ocean off-limits for drilling. Now is the time to draw the line in the tundra and end leases in the Arctic once and for all.

We’re at a critical moment. This year will likely be the hottest year in history, and temperatures in 2024 could easily break new records. The Arctic is on the front lines of climate change. It’s also on the front lines of climate action. The decisions we make there reverberate beyond those landscapes—for good and for ill. We need President Biden to make the right call.