Society could be devastated by 2050 through twenty days of lethal heat per year, collapsed ecosystems, and more than 1 billion people displaced if climate change is not curbed and proper measures were swiftly implemented, a think tank report backed by a former Australian military chief warned.

The Melbourne-based Breakthrough National Center for Climate Restoration paper does not draw on a scientific study, but rather tries to create future scenarios based on existing research.

"After nuclear war, human-induced global warming is the greatest threat to human life on the planet,” a retired admiral and former head of the Australian Defense Force, Chris Barrie, said in its foreword.

"A doomsday future is not inevitable. But without immediate drastic action our prospects are poor," he warned.

The report forecasts a potential global catastrophe in which more than a billion people are displaced, food production drops off and some of the world's most populous cities are left partially abandoned.

The study's authors, climate researchers David Spratt and Ian Dunlop, alerted from the effects of climate change which pose as "near-to-mid-term existential threat to human civilization."

“If global temperatures rise 3 degrees Celsius by 2050, 55% of the world's population across 35% of its land area would experience more than 20 days of lethal heat per year, beyond the threshold of human survivability,” they noted, leading to the collapse of many ecosystems such as in the Arctic, the Amazon rainforest and the coral reef systems.

In addition, there would be more than 100 days a year of deadly heat across West Africa, tropical South America, the Middle East and Southeast Asia, leading to over 1 billion people being displaced.

The authors of the paper argue that food production would decrease due to the "catastrophic decline" in insect populations, weather too hot for humans to survive in considerable food-growing areas and chronic water shortages, and prices would surge.

"The social consequences range from increased religious fervor to outright chaos. In this scenario, climate change provokes a permanent shift in the relationship of humankind to nature,” the paper indicated.