A climate change think tank is warning of an environmental catastrophe within three decades that will threaten the existence of humanity.
Australian organisation Breakthrough said in its report the current research on climate change is too conservative.
It said there is an urgent need to build a zero emissions industrial system, as well as a global response on the scale of World War II emergency mobilisation.
The report said that feedback cycles could push warming to 3C by 2050, making climate change a "near- to mid-term existential threat to human civilisation".
Read the report here
It outlines a scenario where "35 percent of the global land area, and 55
percent of the global population, are subject to more than 20 days a year of lethal heat conditions, beyond the threshold of human survivability".
Ecosystems such as the Arctic, Amazon rainforest and the coral reef systems collapse, and the heat displaces more than a billion people from the "tropical zone", and agriculture becomes "nonviable in the dry subtropics".
"The lower reaches of the agriculturally-important river deltas such as the Mekong, Ganges and Nile are inundated, and significant sectors of some of the world's most populous cities - including Chennai, Mumbai, Jakarta, Guangzhou, Tianjin, Hong Kong, Ho Chi Minh City, Shanghai, Lagos, Bangkok and Manila - are abandoned.
"Ten percent of Bangladesh is inundated, displacing 15 million people."
The report states that armed conflict between nations over resources is likely and nuclear war possible.
Breakthrough research director David Spratt told Morning Report if the commitments from the Paris climate talks were not improved the world was heading for 3C or more of warming.
He said top scientist Hans Schellnhuber, science advisor to German Chancellor Angela Merkel and Pope Francis, recently said if we continued down this present path there was a real risk that human civilisation would end.
"He says 'the human species will survive somehow, but we will destroy almost everything we have built over the past 2000 years'."
Mr Spratt said all the worst climate change scenarios were now on the table.
He said studies showed communities around the world believed climate change was the most important issue society faced, and the private sector needed to step up.
"The business sector, who as you know wield great influence in our political system, they have been sitting on their hands and not providing leadership, and I think that's the really big key."