The devastating defeat of Hillary Clinton and the environmental agenda we hoped she would support has given American environmentalists a key opportunity to remake the movement and create a "Bernie Sanders Revolution" that will help stop Donald Trump in his first 100 days in office and lead us into a greener future.

Here are three key steps we must take right now:

1. Do everything possible to stop Donald Trump.

In terms of administrative action, expect Trump to try to gut the U.S. Environmental Protection Agency, push an intense fossil-fuel agenda through the Departments of Energy and Interior, and over-ride federal laws whenever possible.

To fight these actions, environmental organizations will need to take to the streets and the courts—non-violent direct action as well as lawsuits will help slow or undermine Trump's agenda and draw media and public attention to our side.

In terms of congressional action, we should expect the worst from Trump and the Republican-controlled Congress. Remember all of those radical anti-environmental bills that were pushed forward when the Tea Party seized control of the U.S. House in 2010? They will come back to haunt us. So too will all of the bills that a Democratic Senate and Obama vetoed over the last 6 years.

Expect an attempt to radically gut the Endangered Species Act, National Environmental Policy Act, Clean Water Act and other federal laws. We will need a united Democratic Party in the U.S. Senate—including some filibusters—along with a couple key moderate Republicans who don't trust Trump. We must work in Washington, DC to make that happen.

2. Ignite and reform the mainstream environmental movement.

In the same way that the Bernie Sanders Revolution is igniting and reforming the mainstream Democratic Party, so too must we ignite and reform the mainstream environmental movement. We need to sweep out the old tactics and ideas and sweep in a bunch of new aggressive people that have fire in their belly.

Over the last 8 years, we've watched much of mainstream American environmentalism become way too soft as it tried to nudge Obama forward rather than lead with an aggressive agenda. That nudging tactic hardly worked before, and now with Trump in power it must be completely discarded.

The environmental movement needs a new independent voice that is not beholden to a political party, or to major funders and purse strings. We can't speak truth to power if those in power are providing the paycheck. Environmentalists need to be guard dogs, not lap dogs. We need to speak for people and our environment, and not be greenwashed mouthpieces for any institutional or corporate agenda.

3. Engage local people and local politics.

If there's one thing the 2016 election taught us, it's that people matter and populism is alive again in America. Sanders' populism almost unearthed Clinton's political machine. Trump's populism de-throned two huge political powers—Clinton's Democratic Party and Bush's Republican Party.

We need to end the top-down focus of environmental organizations where a handful of mainstream groups and funders define the environmental agenda, and we must re-focus on local people and local communities. The American people want clean air, clean water, and protected landscapes and wildlife, but will only support those issues if they feel deeply connected to them. We need to support thousands of small and grassroots groups protecting local wetlands, parks, wildlife and rivers. We need to de-centralize environmentalism and connect it to where people live, work and play.

The first 100 days of the Trump administration must be the first 100 days of a new agenda for the health of our planet.

Sanders proved that the American public is thirsty for change. Stopping Trump, reforming mainstream environmentalism, and engaging local people and politics must be our agenda to create a "Bernie Sanders Revolution" for the environmental movement.

Gary Wockner, PhD, is a Colorado-based environmental activist and the author of the 2016 book, River Warrior: Fighting to Protect the World's Rivers. Contact: Gary@GaryWockner.com.