"Drought, wildfires, heat waves, extreme storms, mudslides, rising sea levels, and much, much more. In terms of climate change, the debate is over," declared Sen. Bernie Sanders (I-Vt.) at the climate movement's state of the union on Wednesday. "The issue in front of us is not a scientific debate. It has everything to do political will."

Urging listeners to "knock on doors" and "get involved in grassroots politics," Sanders denounced climate change deniers and those who support using coal and natural gas, adding: "What we are about is telling Donald Trump and the Koch brothers and all of these people that their days are numbered. Fossil fuels' days are numbered. We are going to transform our energy system."

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While President Donald Trump, who delievered his first State of the Union address on Tuesday, failed to even mention "climate change"—as did the Democrat charged with responding to him, Rep. Joe Kennedy III (D-Mass.)—environmental leaders came together a day later for an event called "Fossil Free Fast: The Climate Resistance."

The purpose of Wednesday's event, hosted by the group 350.org, was to draw attention to the global climate crisis and launch the Fossil Free U.S. campaign, which calls for a "an immediate halt to all fossil fuel projects, and a fast and just transition to 100 percent renewable energy."

Bill McKibben, a 350.org co-founder who spoke at the event, outlined three tasks that citizens can take on to contribute to the transition: "One, demand a fast, just transition to a hundred percent renewables in your community; two, make sure fossil fuels stay in the ground; three, turn off the spigot of dollars that keeps the spigot of oil and gas flowing."

Other speakers who advocated for building a #ClimateResistance against Trump and the Republicans, and uniting local struggles to fight for a #FossilFree world, included Hip Hop Caucus founder Rev. Lennox Yearwood, Jessica Lorena Rangel of Houston Eyes of a Dreamer, Jacqueline Patterson of the NAACP, Cherri Foytlin of the Water is Life Camp in Louisiana, and Varshini Prakash of the Sunrise Movement.