Big news in national politics, everybody. Bernie Sanders and Oregon's Senator Jeff Merkley have proposed a bill that would ban all new oil, gas, and coal development on federal land.

From Mother Jones:

Bernie Sanders announced on Wednesday afternoon his support for a new climate bill that would ban all new fossil fuel development on US federal lands and terminate current leases that aren't producing. The bill, called the "Keep It In The Ground Act," would also ban offshore drilling for oil and gas in the Arctic and the Atlantic and would stop new leases for offshore drilling in the Pacific and the Gulf of Mexico.

"I believe all of us have a moral responsibility," Sanders told the rally at the Capitol in Washington, DC, which also featured Bill McKibben, the founder of environmental advocacy group 350.org. "That's just the simple truth."

There are a few things to take away from this. But first, let's be clear:

This bill has very little chance of passing, considering how entrenched the federal government is in the business of fossil fuel production. Also: Republicans. Even Merkley has admitted as much.

But this is big. It's one of the rare times that we've seen something called supply-side climate policy enter mainstream politics. When most politicians—including our own Governor Jay Inslee—have tried to tackle climate policy, they usually go for a "demand-side" approach. That means trying to pass a clean fuel standard, for instance, or taxing carbon in a way that makes it less attractive to pollute. A supply-side climate policy, however, is much more confrontational. If politicians followed supply-side thinking, they'd take a stand against Shell drilling in the Alaskan Arctic. They'd be taking a direct stand against a lot of fossil fuel companies' bottom lines. And that's why you never hear politicians talk about it.

Merkley breaks down the basics of supply-side thinking here:

The idea that we need to keep 80 percent of fossil fuels in the ground in order to avert catastrophic climate change is hardly a popular approach with energy companies that assess their value based on the number of proved reserves of oil, gas, and coal those companies have in the ground. By declaring 80 percent of the world's reserves off-limits, Sanders, Merkley, and five other Senate cosponsors would be hitting the brakes and making a sharp turn away from national energy and climate policy to date—which, arguably, is in line with the type of shift that we need.

That said, there's still debate among climate policy wonks about whether supply-side solutions would work. David Roberts at Vox, for example, can recognize the political value of activism against big, new fossil fuel projects, but he's not totally convinced of the value of supply-side climate policy.

I can't say I know the answer one way or the other. I'm no expert. But to me, a willingness to support supply-side climate policy is shorthand for a political will to stand up to the fossil fuel industry in a way we've never seen before. Odds are seven senators wouldn't even float this idea if they knew they wouldn't have some modicum of public support—public support bolstered by big, dramatic direct actions from climate activists in Seattle and Portland.

And even though this bill probably won't pass, it means that idea—that political will—has at least entered the national conversation.

That's huge. And in my mind, local activism has contributed to the shift.