We don’t have much time to tackle climate change. A new report by the UN Intergovernmental Panel on Climate Change finds that we need to reduce carbon emissions by 45 percent in the next 12 years to keep the earth from heating up “only” 2.7 degrees Fahrenheit. This isn’t a problem for future generations; this is an emergency now.

Into this crisis comes a demand for a Green New Deal, a call to mobilize the federal government to tackle this threat. Led by the young organizers of the Sunrise Movement, the campaign received a signal boost when Congresswoman-elect Alexandria Ocasio-Cortez joined its members during a sit-in at Democratic House leader Nancy Pelosi’s office.

The fact that the earth is rapidly warming is reason enough to pay attention. But there are three additional reasons why the Green New Deal should excite Democrats and progressives.

First, it proves that the grass roots can drive the Democratic agenda. Just a few months ago, virtually no one in DC policy circles was discussing ambitious climate plans. But four years ago, that was also true about a $15 minimum wage—which only became a priority after service-sector workers started to pressure cities, states, and the federal government to ensure that nobody working a full-time job lives in poverty. And it’s the same with Medicare for All. After Trump’s attacks on health care, activists have not been content merely to clean up the Republicans’ mess and embrace Obamacare; instead, they want every American to have genuine access to public health care.

Organizers across the country are forcing Democrats to fully confront real issues. The party can no longer get away with offering milquetoast solutions that don’t address the scale of the problems. And so far, the people most affected by the inequities in our economy are actually the ones setting the agenda. It is telling that the Green New Deal is being helmed by millennials, who will live long enough to see the most vicious effects of climate change.

Second, a Green New Deal helps solve the Democrats’ ideas problem. Whereas Republicans have continually pointed to “small government” as their ideal (even as they’ve built up a massive carceral, military, and surveillance state), Democrats often have trouble communicating what they stand for. Ocasio-Cortez describes the Democrats, correctly, as the party that electrified the nation during the Great Depression and developed the space program that put a man on the moon. Fighting climate change is a challenge worthy of this party—and by tying climate action so explicitly to new jobs, high-tech training, and investment in collapsing communities, it can be sold as something that benefits people and the nation as a whole. With the Green New Deal, Democrats can honestly say they are the party ready to take bold action to save the planet.

Finally, we are not prepared for the next recession. With low interest rates, corporate balance sheets bloated with cash that companies won’t spend, and workers without the power to demand higher wages, the next recession will be just as devastating as the previous one and will require an even bigger response. During the 2008 financial crisis, progressive groups had to scramble to prepare their proposals to rescue the economy. The resulting plan funded infrastructure insufficiently and was too focused on temporary spending. Until now, no progress has been made in addressing these problems. This is where a Green New Deal will be essential. The next recession will see a shortfall in investment as well as millions of unemployed people badly in need of jobs—both of which a Green New Deal can address in a generationally transformative way.

Some criticize the champions of a Green New Deal for not yet offering specifics. But the goal is for congressional hearings in 2019 to create a bill for 2020. These hearings will be important for making clear the scope of what needs to be done. Even better, this process will build energy and excitement within the Democratic coalition. The Green New Deal could solve two problems at once: It could save the Democratic Party as well as the planet.