"What is the worst thing that could happen? And are we prepared for this?" Those are the fundamental questions about climate change that David Spratt, research director of the Breakthrough National Centre for Climate Restoration in Australia, is trying to answer.

Spratt and Ian Dunlop, a former fossil fuel executive aimed to piece together the social implications of climate change—not just the ecological ones. The very broad strokes aren't too different from last year's report from the UN Intergovernmental Panel on Climate Change, which concluded that we have just over a decade to prevent the absolute worst climate outcomes. That report focused on the now-inevitable two degrees of warming, the temperature at which 411 million people living in cities will face water scarcity, crops begin failing, and all coral dies off. But Spratt and Dunlop wanted to know what the absolute worst could be.

"The IPCC report tends to talk about the middle outcomes, like, there's a 50 percent chance of this," says Spratt "So we thought it was important to ask, 'What are the high-end impacts?' Because in risk management, the cost of the damage associated with high-end impacts are so great that you have to avoid them."

And the costs are high indeed. The research Spratt and Dunlop have compiled makes the case that in its most extreme, climate change is "a path to the end of human civilization and modern society as we know it." Understanding just how high the stakes really are, Spratt argues, is absolutely necessary if we're going to take the issue seriously and try to avoid the worst possible outcomes.

GQ: Can you explain briefly what makes this report unique?

David Spratt: Let's take, for example, the agreement made in Paris in 2015, where various countries made commitments to reduce their emissions. In fact, they're tracking a little bit worse than their commitments at the moment, but the commitments that have already been made will be consistent with the world warming by three degrees. And with long term impact, the Paris path may in fact be a path of four degrees or more warming. So, our policy paper, just drawing on the peer reviewed scientific literature, was to draw a snapshot of what the world would look like at three degrees warming and a half meter sea level rise, and then drew some conclusions from it. And at three degrees warming, you see loss of lands to desertification, you see a declining crop yields, and, because of the heat, you get a decline in the nutrition content of food, and chronic water shortages. Now, those physical conditions then have social consequences.

And what were some of those consequences?

We actually relied on Age of Consequences, which is a report published in the United States in 2007. And it was put together by a group of Washington national security analyst insiders, together with a former director of the CIA. So this was a very Washington view. And back in 2007, they asked what would happen if the world warmed by three degrees and we simply reprinted this scenario. It said that there would be what they called massive, nonlinear societal events, that is social breakdown. They said nations around the world will be overwhelmed by the scale of the challenge, and the internal cohesion of nations will be under great stress, including the United States, in their words, as a result of dramatic rise in migration, and changes in agricultural patterns and water availability. So there is American national security, CIA insiders saying the social cohesion in the United States will break down. The social consequences range from increased religious fervor to outright chaos, and climate change will cause a permanent shift in the relationship of humans to nature. The consequence is the breakdown of states and the breakdown of relationships between states on a global scale.