A senior adviser to Joe Biden’s 2020 campaign joined with the Democratic National Committee leadership on Thursday to stop a resolution that would have dedicated one of the 12 presidential debates exclusively to the issue of climate change. At a party conference in San Francisco, Symone D. Sanders spoke out against the measure, claiming it involved rule changes that would be “dangerous territory in the middle of a democratic primary process.”

“That’s a debate we should have had last summer,” Sanders said, explaining that allowing a debate on climate change would necessarily mean debates on other topics as well. “That’s not a feasible conversation to have this summer as we are…a third of the way through the Democratic primary process.” She continued on to note that the television networks were the ones to decide the substance of the debates, not the party.

Sanders’ statements contradict previous assurances by Biden that he was indeed supportive of calls for a climate debate—a discrepancy the climate action group Sunrise Movement called out on Twitter.

.@SymoneDSanders is trying to shut down the movement for a #ClimateDebate right now at the @DNC meeting.



But her boss @JoeBiden has publicly supported it multiple times.



So…what’s going on?https://t.co/O3p8OtXd4o — Sunrise Movement (@sunrisemvmt) August 22, 2019

In May, the former Vice President received a D-minus report card from the environmental group Greenpeace, and his climate plan, released the next month, explicitly allows for the proliferation and expansion of fossil fuel energy. Yet Sanders insisted she was not acting as a representative of his campaign in opposing the debate resolution.

While she was speaking, the senior Biden adviser was heckled with boos erupting from the audience. The room had been packed by Sunrise Movement in anticipation of the vote. Roughly 100 activists were in attendance to make their voices heard.

Calls for a climate debate have grown amidst dire warnings from the global scientific community. While initially, activists, progressives, and environmental groups led the charge, state officials and presidential candidates have gotten on board with the climate debate. The resolution had 70 co-sponsors.

Yet the party leadership has consistently resisted calls for single-issue debates. Earlier this month, DNC Chair Tom Perez affirmed two climate change forums, hosted by CNN and MSNBC, in a resolution. The move was seen as a gesture of compromise indication of the likely fate of the debate resolution. But it did not lessen the blow when the 30-member resolutions committee shot down the debate resolution 17 to 8 after more than two hours of intense argument.

Angered and disappointed by the result, the activists interrupted the meeting, yelling and chanting. One woman stood atop a chair and shouted, “We’re asking you to fight for our futures!”

“We deserve a chance at a livable future,” cried another activist, according to HuffPost. “We deserve a climate debate.”

For a party trying to put forward a unified front heading into a presidential election, the optics were rough.

Speaking with Paste, climate activist and documentary filmmaker Josh Fox excoriated the DNC’s decision.

“It is utterly unconscionable that the Democratic Party would refuse to acknowledge the importance of climate change,” Fox said. “At the root of this denial is their embrace of fracked gas- which must be banned if we are to do anything serious about climate change.”

Erich Picah, President of Friends of the Earth Action, a DC-based environmental group, issued a similar statement that also included Sanders.

“The DNC and Biden’s advisor Symone Sanders have failed an important climate leadership test,” she said. “All the climate resolutions and platitudes are essentially meaningless without a DNC sanctioned climate debate to engage the country. It is especially concerning to see Biden’s senior advisor lobbying to stop conversation on climate change.”

Still, Sunrise spokesperson Sofie Karasek found a silver lining. The DNC did move forward with a resolution to allow candidates to appear alongside one another at unsanctioned climate forums. In a statement, Karasek pledged, “In the coming days and months, we’ll keep fighting to make sure the DNC and Tom Perez treat the climate crisis like the emergency that it is, and give it the airtime and attention that it deserves.”

But the time for small victories is most assuredly over. The prognosis for the planet remains grim. On Monday, news broke that Sao Paulo, Brazil, had been blacked out by smoke from forest fires nearly 3,000 kilometers away. Up 80 percent from last year, the fires are reportedly the direct result of human activity. They now threaten the Amazon rainforest, which is the largest on Earth, responsible for producing 20 percent of the oxygen in the atmosphere, and which has been experiencing drought due to climate change.

The timing of the assault on one of the world’s most precious and fragile ecosystems could not be worse. In October, for example, the UN’s Intergovernmental Panel on Climate Change released an alarming report giving humanity a 12-year time period in which to implement changes on an unprecedented scale in order to keep the global temperature increase within 1.5 degrees Celsius of pre-industrial levels. Any warmer, the report warned, the consequences would be devastating. Subsequent studies by other organizations have suggested that the IPCC’s findings were overly optimistic.