Skating on thin ice: Antarctica’s Larsen C ice shelf.

Winter is coming — not here, perhaps, but in Antarctica. For those increasingly worried about climate change, the Antarctic winter can’t come a moment too soon.

Earlier this month, researchers with the British Antarctic Survey released new aerial video showing the widening crack in the Larsen C ice shelf — a chasm so deep and so long it stretches to the horizon.

February is high season for scientistswho monitor the ecosystem of the planet’s coldest, windiest, most remote continent, so this is the time of year when the most important, telling scientific findings are made.

©Jeff Orlowski, Chasing Ice.

©Jeff Orlowski, Chasing Ice.

In all, the Larsen C crack is 160 kilometres (100 miles) long and some 460 metres (1,500 feet) wide at its widest point. Left unchecked, the rift will cleave off a monster iceberg the size of Wales — or Delaware, if you’re thinking in U.S. terms — in the foreseeable future.

If, or more likely when, it happens, the iceberg will represent 10 percent of the entire ice shelf. As recent findings in the Arctic have shown, ice melts increase more rapidly in pace once they begin. Today’s 10 percent will be tomorrow’s 25 percent, and so on.

There is precedent, even in Antarctica. The Larsen A and B ice shelves collapsed in 1995 and 2002 respectively. The Antarctic research group that monitored the Larsen B collapse at the time noted that the event followed a sudden and unsustainable band of warm air in one of the world’s fastest warming places.

©Jeff Orlowski, Chasing Ice.

©Jeff Orlowski, Chasing Ice.

Ice shelves play an important role in Antarctica’s ecosystem, scientists say, because they act like bookends, holding together massive stores of loose ice on the continent.

If those bookends collapse, it will cause land ice to melt and glaciers to split off into the ocean, boosting sea levels. Since the Larsen B shelf’s break upglaciers behind it have flowed into the sea at a rate six times faster than before the shelf’s collapse.

Satellite imagery shows the western edge of Antarctica is also developing cracks, including the Pine Island Glacier ice shelf. 

Not all ice melt can be spotted from the surface. Massive meltwater lakes deep inside ice fields can flow out to sea through tunnels deep under the ice, making them harder to spot. 

Ice breakup in the Arctic has been measured more closely than in the southern continent, for obvious reasons.

©Jeff Orlowski, Chasing Ice.

©Jeff Orlowski, Chasing Ice.

The Arctic is closer to major population centres, and more exposed to warming air in the more populated Northern Hemisphere. Melting ice has given rise to the real possibility that the Northwest Passge will be ice-free during the summer in just a matter of years. That will open the entire region to shipping, not to mention oil drilling. Before long, the Northwest Passage will a realistic geographical and economic alternative to the Panama Canal. International shipping lanes will be affected, and along with them the economic prospects of Panama, Russia and Canada, among other countries.

The recent findings in Antarctica have prompted renewed interest in the work of nature photographer James Balog and filmmaker Jeff Orlowski’s 2012 documentary Chasing Ice, in no small part because Balog photographed a massive ice calving in the Arctic while on assignment for National Geographic.

Video footage of an ice shelf the size of a small city cleaving off into the sea off  Greenland's coast went viral. A four-minute excerpt of the largest glacier calving ever filmed has 46 million views on YouTube.

What makes Chasing Ice particularly relevant today is that Balog was initially a climate-change skeptic when, more than 10 years ago now, he took on his first National Geographic assignment in the far north.

©James Balog, National Geographic.

©James Balog, National Geographic.

It wasn’t long, however, before he became convinced of the impact humans are having on the planet. He has been working ever since to get the message out.

This past November, the Arctic was 20 degrees warmer than average, warmer even than the most liberal projections had predicted.

No one can predict with any degree of certainty, of course, what effect melting sea ice will have in the immediate, short-term future, let alone future generations.

One thing is immediately clear, though: The planet is skating on thin ice.