Unless nations quickly muster the political and social will to engineer an emissions-free industrial system, the impacts of a warming planet are likely to be so great as to cause human civilization to collapse by 2050. That’s the scenario put forward in a May 2019 report published by Breakthrough—National Centre for Climate Restoration, a think tank based in Melbourne, Australia.

Calling many reports created for climate policymaking purposes “conservative and reticent” with their risk assessments, the report’s overview declares that “climate change now represents a near- to mid-term existential threat to human civilization.” It defines an existential risk to civilization as one “posing permanent large negative consequences to humanity which may never be undone, either annihilating intelligent life or permanently and drastically curtailing its potential.”

The report, “Existential Climate-Related Security Risk: A Scenario Approach,” was authored by David Spratt, a research director at Breakthrough, and Ian Dunlop, former chairman of the Australian Coal Association and chair of the Australian Greenhouse Office Experts Group on Emissions Trading. They argue the greatest threat lies “disproportionately in the ‘fat-tail’ outcomes” of the risk curve, i.e., the more extreme possible outcomes—scenarios that had previously been understated.

The 11-page report lays out a scenario by which climate change causes catastrophic impacts to human society. Key to its proposition of a potential 2050 doomsday is inaction by policymakers to take steps between now and 2030 to reduce the degree of warming. Under this scenario, if global human-caused greenhouse emissions continue to climb until 2030, that would cause “at least 3° C of warming”—a rise considered by some scientists to be catastrophic.

The report’s recommendation comprises an unprecedented call to action.

“To reduce this risk and protect human civilization, a massive global mobilisation of resources is needed in the coming decade to build a zero-emissions industrial system,” it states.

Writing in the foreword of the report, Adm. Chris Barrie, a member of the Global Military Advisory Council on Climate Change and former chief of the Australian Defence Force, states: “A doomsday future is not inevitable! But without immediate drastic action our prospects are poor. We must act collectively. We need strong, determined leadership in government, in business and in our communities to ensure a sustainable future for humankind.”