Earth Could Face 'Hothouse' Climate With Uninhabitable Parts, New Study Warns

A new international study has found that the world could face a "hothouse" climate where efforts to reduce emissions will have no impact if the Earth's global average temperature increases by a further 1 degree Celsius.

Researchers from around the world contributed to a study titled "Trajectories of the Earth System in the Anthropocene", which has been published in the international journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).

The research found that Earth is heading for a crisis point known as a "hothouse" climate. If this tipping point is reached, average temperatures may climb 5C higher than pre-industrial temperatures which in turn could cause rises in sea level of up to 60 meters. If this happens much of the world would be uninhabitable for humans.

Domino effect is possible says lead author

Lead researcher Professor Will Steffen from the Australian National University (ANU) explained that Earth system processes known as feedbacks could be triggered if human emissions raise global temperatures to 2C above pre-industrial temperatures.

"The real concern is these tipping elements can act like a row of dominoes."

"The real concern is these tipping elements can act like a row of dominoes," Professor Steffen said.

"Once one is pushed over, it pushes Earth towards another. Global average temperatures are currently just over 1C above pre-industrial temperatures and rising at 0.17C each decade," added Professor Steffan.

"Even if the Paris Accord [Agreement] target of a 1.5C to 2C rise in temperature is met, we cannot exclude the risk that a cascade of feedbacks could push the Earth system irreversibly onto a 'hothouse Earth' pathway," the study says. "As yet [these initiatives] are not enough to meet the Paris target." 

Paris agreement may have no effect

Professor Steffen goes on to say that although it's not just humans responsible for the rise, they are playing the largest part and need to work collaboratively to 'greatly accelerate the transition towards an emission-free world economy'.

"The impacts of a hothouse earth pathway on human societies would likely be massive, sometimes abrupt, and undoubtedly disruptive."

He insists that a radical collaborative action is needed to stabilize the Earth in an interglacial-like state. The study looked at 10 feedback processes, some of which can cause "the uncontrollable release" of carbon back into the atmosphere, after it had been stored in the earth.

These processes can include permafrost thaw, Amazon rainforest dieback, a reduction of northern hemisphere snow cover, a loss of Arctic summer sea ice, and a reduction of Antarctic sea ice and polar ice sheets. The exact timeframe for these events to happen isn’t detailed in the report, but the authors hypothesized that it could happen in less than two centuries.

"The impacts of a hothouse earth pathway on human societies would likely be massive, sometimes abrupt, and undoubtedly disruptive," the study states.

The study was published in PNAS.