United Nations climate chief Christiana Figueres on Wednesday highlighted the urgency of a global climate agreement, warning that “time is running out.”

In an interview with the Associated Press, Figueres said that the upcoming negotiations in Paris, known as COP21, were a make-or-break point.

“We are at five minutes to 12 and Paris is the 12 o’clock strike of the clock,” she told the news agency.

Failure to reach a global, binding agreement at Paris would mean “we are going to be playing with fire,” she said.

Figueres recently welcomed a statement by a group of leading international scientists calling for bold action on climate, stating, “The world’s leading researchers on climate have underlined the crucial importance of nations focusing on a long term goal—call it zero emissions, net zero or climate neutrality. The overwhelming consensus is that Paris 2015 needs to send an unequivocal signal that the world will take a path towards a steep and deep decline in greenhouse gas pollution by the second half of the century.”

Yet many climate activists are skeptical that any deal coming out of what they dub the “Conference of Polluters” can result in the kind of agreement that would stave off catastrophic climate change.  As Council of Canadians’ Brent Patterson wrote, this is “because the pledges being made by countries in advance of the COP21 in Paris are simply insufficient.”

But the stakes couldn’t be higher, Pablo Solón, Executive Director of Focus on the Global South, wrote earlier this year:

    The nature of climate change with its feedback mechanism is such that what we did in the past is what we reap now. Following this logic, what we do now is what we will reap in the next 10 years, and if the current text is to be the basis of that future, we will have none of which to speak.