Our study suggests that human-induced global warming of 2°C may trigger other Earth system processes, often called "feedbacks", that can drive further warming - even if we stop emitting greenhouse gases", says lead author Will Steffen from the Australian National University and Stockholm Resilience Centre.
Sea levels would rise considerably due to melted polar ice caps. This summer dozens of people have died in wildfires and heat waves from the USA to Asia, giving the world an insight into what could lie ahead.
The threshold will be reached when average global temperatures are only around 2C higher than they were in pre-industrial times, research suggests.
Many scientists argue that we have entered a new geological era, the Anthropocene, in which human activity is directly affecting the planet. According to the researchers, keeping global warming to within 1.5-2 degrees Celsius may be more hard than previously assessed.
Commenting on the findings, Chris Rapley, Professor of Climate Science at University College London said: "Previous research has shown that an increase in the mean global temperature of 11-12C would make more than half of the land area now occupied by humans uninhabitable". "We've always realized there might be a point of no return", she said. They are already 1C higher, and rising. "It would simply be unbearable for our society".More news: Lombok natural disaster : Strong aftershock amid rescue efforts
"Collective human action is required to steer the earth system away from a potential threshold and stabilise it in a habitable interglacial-like state".
"What we do not know yet is whether the climate system can be safely "parked" near 2ºC above pre-industrial levels, as the Paris Agreement envisages", shared Schellnhuber.However, there are no binding targets, and the U.S. later pulled out, dealing a blow to global efforts to form a united front against climate change.
The feedbacks are permafrost thaw, loss of methane hydrates from the ocean floor, weakening land and ocean carbon sinks, increasing bacterial respiration in the oceans, Amazon rainforest dieback, boreal forest dieback, reduction of northern hemisphere snow cover, loss of Arctic summer sea ice, and reduction of Antarctic sea ice and polar ice sheets.
This was revealed by an worldwide study led by Will Steffen from the Australian National University (ANU). Once one is pushed over, it pushes Earth toward another", said Johan Rockström, co-author of the report published in the Proceedings of the National Academy of Sciences and executive director of the Stockholm Resilience Centre. "It may be very hard or impossible to stop the whole row of dominoes from tumbling over", co-author Johan Rockström told Stockholm Resilience Centre.More news: Syrian First Lady undergoes treatment for early-stage breast cancer
"It doesn't really change the imperative that we need to manage the situation. We totally hand over our fate to an Earth system that starts rolling out of equilibrium", he added.
"At a time of the widespread rise of right-wing populism, with its associated rejection of the messages of those perceived as "cosmopolitan elites" and specific denial of climate change as an issue, the likelihood that the combination of factors necessary to allow humanity to navigate the planet to an acceptable "intermediate state" must surely be close to zero", Rapley said.More news: Should Boris Johnson apologise for his comments about burkas?