On Dec. 12, nearly 200 nations approved the “Paris Agreement.” The 32-page document spells out humanity’s new, official plan to confront the crisis of climate change. The accord was negotiated in a secure facility in the Paris suburb of Le Bourget. Public demonstrations across France were banned under the “state of emergency” imposed after the Nov. 13 terrorist attacks in Paris that killed 130 people. Activists defied the ban, saying that same phrase, “state of emergency,” describes the planet’s climate. Protests, at times violently repressed by police, occurred throughout the two-week United Nations summit, as people from around the world demanded a fair, ambitious and binding climate treaty to avert the worst consequences of global warming.

“What I see is an agreement with no timetables, no targets, with vague, wild aspirations,” British journalist George Monbiot told me two days after the talks ended. “I see a lot of back-slapping, a lot of self-congratulation, and I see very little in terms of the actual substance that is required to avert climate breakdown.”

Monbiot’s position contrasts with many in the environmental movement, who see the negotiation results as a positive development. “Just about every country in the world made a commitment to either cut their own carbon or to peak the growth in their emissions,” Michael Brune, the executive director of the Sierra Club, countered. “There was also an explicit acknowledgment that what was committed to is not nearly enough, and so there was a process that was established to take stock of the progress that’s being made and then to commit to continuous reductions in the years ahead.”

The conference opened with the largest gathering of heads of state in history. Dr. Hoesung Lee, chair of Intergovernmental Panel on Climate Change (IPCC), a group of almost 2,000 scientists that publishes the world’s scientific consensus on climate change, addressed the leaders, saying: “The climate is already changing, and we know it’s due to human activity. If we carry on like this, we risk increasingly severe and irreversible impacts: rising seas, increasingly severe droughts and floods, food and water shortages, increased immigration from climate refugees, to name just a few.” Just about everywhere on the planet, climate science is accepted as fact. It is only in the United States, the largest polluter in world history and home to some of the wealthiest and most politically influential fossil-fuel corporations, that climate-science deniers are given credence.

Climate scientists at the IPCC have provided different global-warming scenarios, describing what the world might look like if the planet warms to varying temperatures. We have already warmed 1 degree Celsius over preindustrial levels, with devastating impacts. The Paris Agreement’s central tenet is the pledge to hold “the increase in the global average temperature to well below 2 degrees C (3.6 degrees F) above preindustrial levels and to pursue efforts to limit the temperature increase to 1.5 degrees C (2.7 degrees F) above preindustrial levels.”

These seemingly small differences matter. With a rapid decarbonization of the global economy, with a rapid shift to nonpolluting renewable energy, we could limit the temperature rise to 1.5 degrees Celsius. In this scenario, small island nations can survive the expected sea-level rise. At 2 degrees Celsius, polar ice melts, water warms and thus expands, and global sea levels rise more than 3 feet. Several small island nations, like the Maldives or the Marshall Islands, will be completely submerged and will disappear. The 1.5 degree goal was included in the Paris Agreement, but, as George Monbiot noted, “it’s almost as if it’s now safe to adopt 1.5 degrees centigrade as their aspirational target now that it is pretty well impossible to reach.”

Author and activist Naomi Klein said the deal will “steamroll over crucial scientific red lines ... it is also going to steamroll over equity red lines.” She added, “We know, from doing the math and adding up the targets that the major economies have brought to Paris, that those targets lead us to a very dangerous future. They lead us to a future between 3 and 4 degrees Celsius warming.”

Asad Rehman, of Friends of the Earth, explained that equity red line as “support for the most vulnerable, the poorest people, who are really losing their lives and livelihoods and who are going to deal with ever-increasing climate impacts, mostly because of the responsibility of rich, developed countries who have grown fat and rich from carbon pollution.” In the Paris Agreement, this support is called “loss and damage,” meaning financial payments from the rich countries to poor countries suffering severe impacts of climate change. “Rich countries, who are responsible for this crisis ... now want to shift the burden of responsibility from the rich to the poor,” Rehman added. “Unfortunately, the legacy President Barack Obama will leave here is a poison chalice to the poor, to actually make them pay for the impacts of climate change.”

A broad coalition of climate action organizations has promised an aggressive year of direct action to hasten the end of the fossil-fuel era. As Kumi Naidoo of Greenpeace told me, “Most of us in civil society never said ‘the road to Paris,’ we always said ‘the road through Paris.’”