Earth at Risk of Entering 'Hothouse' State from which there is no Return

Independent - In a summer marked by global heatwaves, wildfires and drought, scientists have warned that things could get considerably worse under a future scenario dubbed "hothouse Earth".

Even if greenhouse gas emissions are reduced, there is a chance human-induced global warming could trigger other processes which will lead to uncontrollable warming, the team at the Stockholm Resilience Centre said. 

As Amazon rainforest is destroyed, Arctic permafrost thaws and Antarctic sea ice melts, these natural feedback mechanisms that currently help store Earth's carbon will instead begin emitting it, scientists at the Swedish institute warned.  

While it is unclear how likely this scenario is, experts agree that were it to happen the runaway warming after this tipping point would be an existential threat to humanity.

"These tipping elements can potentially act like a row of dominoes," said Professor Johan Rockstrom, Executive Director of the Stockholm Resilience Centre. "Once one is pushed over, it pushes Earth towards another. It may be very difficult or impossible to stop the whole row of dominoes from tumbling over."

The prospect of such a situation has been laid out by Professor Rockstrom and his colleagues in the journal Proceedings of the National Academy of Sciences (PNAS).

"We address tipping elements in the planetary machinery that might, once a certain stress level has been passed, one by one change fundamentally, rapidly, and perhaps irreversibly," explained Professor Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research.

"This cascade of events may tip the entire Earth system into a new mode of operation."

Global average temperatures are currently 1C above...