The First Tipping Point Has Arrived: Will It Be The Last ?

"What climate scientists have feared for decades is now beginning to come true: We are pushing the climate system across dangerous tipping points" says Stefan Rahmstorf from the Potsdam Institute.

His dire warning came after two new studies revealed that the Western Antarctic Ice Sheet has crossed a dangerous breaking point. Melting at a much faster pace than originally anticipated, it's unstoppable collapse is already underway:

"A large sector of the western Antarctic ice sheet has gone into a state of irreversible retreat. It has passed the point of no return. This retreat will have major consequences for sea level rise worldwide," warns Eric Rignot, a glaciologist at Nasa and the University of California.

Driven by warming temperatures, the retreat will cause global sea levels to rise by as much as 1.4 meters by the end of this century. This will radically alter coastlines across the globe.

And, according to glaciologist Hamish Pritchard from the British Antarctic Survey, the rise will be uneven: it will especially impact the northeastern coast of the US, and the southern part of China, affecting major financial centers in New York and Hong Kong:

"The rise is pretty exceptional in historical terms, at rates that haven't been seen since the end of the last ice age. And this is the first time we are seeing rates like this with a very large human population."

The two new studies by Nasa, and the University of Washington reveal that global sea level rises will be much higher than predicted by the United Nation's latest climate report which did not factor in the collapse of the West Antarctic Ice Sheet.

The UN's conclusions tend to sit on the more conservative end of the spectrum as they are always drawn from a consensus process.

According to the University of Washington study, under the worst-case scenario, the collapse of the entire ice sheet is about 200 years off, and possibly even up to 1,000 years away.

The retreat would begin slowly, resulting in sea-level rise of less than 1mm a year for a couple of hundred years. But "then boom, it just starts to really go," warns Ian Joughin, a University of Washington glaciologist.

According to Rignot however, both studies are too conservative as they do not include all the potential feedback loops.

Richard Alley, a climate scientist at Pennsylvania echoes that view, arguing that they did not run the worst case scenario, which would accelerate all of this melting to within this century.

The pace and scale of retreat largely depends on whether world leaders can sign off on a new global treaty to rein in carbon emissions when they gather in Paris next December.

Last month, the world's two largest emitters, the US and China stepped up their efforts to lead the charge against global warming. With emissions that match the rest of the world combined, commitment by these two powerhouses is key.

If greenhouse gases continue to rise at their current pace, warming temperatures could destabalize the rest of Antarctica, and the Greenland ice sheet. This would cause sea levels to rise to such a level that many of the world's coastal cities would become inhabitable.

And, according to Pritchard, the most alarming part is not the sea level rise itself, but the implications it has for storm surges across the globe.

The most recent example of this would be Typhoon Haiyan. One of the strongest storms to make landfall in history, it killed over 6,000 people in the Philippines last November as it tore across the archipelago. Fueled by higher sea levels and warmer temperatures over the Pacific Ocean, it was was one of several super storms to form over the Pacific last year.

And, when Hurricane Sandy struck New York City two years ago, it hit an area where the sea level was about a foot higher than it had been a century before.

Pritchard says that places that once had "one in 100 year risk of a serious storm surge may become a one in 10 years likelihood, meaning people have to abandon that place."

"If we have indeed lit the fuse on West Antarctica, it's very hard to imagine putting the fuse out. But there's a bunch more fuses, and there's a bunch more matches, and we have a decision now: Do we light those?" asks Dr. Alley.

The news comes two months after the United Nations released its most sobering account on the state of our climate yet: "Things are worse than we had predicted. We are going to see more impacts, faster and sooner than we had anticipated," said Saleemul Huq from the Independent University in Bangladesh.

That brutal assessment came six months after the Nobel Peace prize-winning body revealed that our planet is warming much faster than expected: temperatures may now breach the upper safe limit of warming within the next 30 years.

In the words of an old James Bond novel: "Once is happenstance. Twice is coincidence. Three times is enemy action."