In 1845, an expedition charged with finding the fabled Northwest Passage between the Atlantic and Pacific oceans came to grief. The fate of Sir John Franklin and his men may become clearer as the old Arctic ice subsides … but at what cost? Jonathan Gornall reports
If only Sir John Franklin could have waited another 160 years or so.
In 1845, the ageing English explorer led a royal navy expedition charged with charting the last reaches of Canada's Arctic north and navigating a route through the fabled Northwest Passage - the elusive shortcut from the Atlantic to the Pacific Ocean, sought by European rulers and traders since the 15th century.
It didn't go well. Franklin, all of his men and both of his ships, HMS Terror and Erebus, disappeared.
Over the next two decades, dozens of expeditions were sent from England to try to discover what had become of them.
They found only scattered artefacts, three graves containing the gruesomely preserved bodies of sailors claimed by disease early in the expedition, and a trail of ship's boats and human remains that hinted at cannibalism and a desperate, doomed overland trek southward to safety.
What they didn't find were the two ships.
According to a message discovered by one expedition under a cairn on King William Island, in what is now Canada's far northern Nunavut territory, the presciently named Terror and Erebus - in Greek mythology, the latter was the region of the underworld through which all the dead must pass - became irretrievably trapped in the winter sea ice.
Last week, Parks Canada, assisted by the Canadian coastguard icebreaker Sir Wilfrid Laurier, began to wind up the latest of what has become a traditional annual summer search for the remains of the ships.
This year, there was no joy - but at the rate the Arctic sea ice is disappearing, the chances of finding them soon are better than ever.
As sonar was scouring the seabed off King William Island in vain for signs of the wrecks of Terror and Erebus, so last week came the news from the US National Snow and Ice Data Centre (NSIDC) that the coverage of sea ice during the Arctic summer had shrunk to its lowest level since accurate measurement became possible.
In 1979, at the start of the satellite era, the ice covered close to 14 million square kilometres. On August 26, according to the NSIDC, it was a mere 4.1 million sq km.
To put that in context, Canada, the world's second-largest country after Russia, occupies almost 10 million sq km. The area of Arctic sea ice remaining is now closer to the size of India's 3.1 million sq km.
The previous low, says the NSIDC, was in 2007. Since then, the Arctic has lost another 70,000 sq km - a chunk almost the size of Turkey - in just five years.
This, says Prof Julian Dowdeswell, the director of the Scott Polar Research Institute in Cambridge, England, is not about rising sea levels. There are, he says two basic kinds of ice in the Arctic and the Antarctic regions.
"One is the large glaciers and ice caps, which cover most of the land and can be kilometres in thickness, and are formed from the precipitation and build-up of snow over long periods," says Prof Dowdeswell.
"The second is the thin, frozen sea surface, which is known as sea ice. Because the sea ice is floating on the surface, whether it's melting or present as frozen water, it has no effect on sea level."
Nothing to worry about then? Not quite.
There are, he says, potential positives: "It means that the Arctic Ocean is more accessible, for navigation, exploration and, in the end, possible exploitation."
Whether that's good or bad depends on your world view. "Some hold the view that the polar regions should be the preserve of untrammeled habitats. Others regard the resources there as potentially useful for humankind," says Prof Dowdeswell. "I'm a scientist. My job, as I see it, is presenting the observations concerning change and it's up to others to decide what they are going to do with that."
What Canada and the other countries whose back yards look out over the Arctic - Denmark, Norway, Russia and the US - are doing is scrabbling to lodge territorial claims, chiefly, but not always, under the auspices of the United Nations Convention on the Law of the Sea - a convention that America, for one, has conspicuously failed to ratify.
For its part, Canada would like everyone to ask its permission before navigating through its northern archipelago, which it regards as part of its internal waterways, but which the world regards as international waters.
It was less than amused in 2007 when the Russians sent an expedition into those waters, dropping a flag on the seabed in the process.
"They're fooling themselves if they think dropping a flag on the ocean floor is going to change anything," said Peter MacKay, who was Canada's foreign affairs minister at the time and now holds his nation's defence portfolio.
"There is no question over Canadian sovereignty in the Arctic."
But there is extreme interest from all parties, not so much in a final opening of a commercially viable Northwest Passage - as convenient as that would be for shipping - as in the untold fossil fuel riches in the region becoming increasingly more accessible thanks to the melting sea ice.
Scientists such as Prof Dowdeswell, however, are not concerned about which countries are poised to become frighteningly oil or gas-rich.
While the disappearing sea ice will not raise sea levels, "It will have effects on biodiversity," he says. "Clearly, there are certain iconic animals that rely on sea ice to a greater or lesser extent" - cue photographs of polar bears and seals apparently stranded on minute ice floes - "so they will have progressively more difficulty in finding the habitat to suit them."
Of wider concern, perhaps, "if less sea ice is being produced," he says, "then that has implications for the formation of dense water and the circulation of the North Atlantic".
When ice forms in the polar seas, not all of the salt in the seawater makes it into the ice. Immediately under forming sea ice is a layer of dense, highly saline water that sinks to the sea floor.
There, it flows south, and "in part the Gulf Stream which warms western Europe is the return flow, in the upper 800 to 1,000 metres in the water column, of that dense southward water flow".
So if you have a lot less sea ice forming, "you also affect the vigour of the North Atlantic circulation system" - and that, in turn, could have all kinds of consequences for world weather patterns.
At the current rate of loss, says Prof Dowdeswell, we are likely to see "almost ice-free conditions in the Arctic, every summer, some time in the next few decades - and whether it's 20 years or 50, I wouldn't like to say".
The question that no one can really answer, he says, "is how much is this a product of natural cycles in the Earth's system, and how much is the change a product of human-induced greenhouse gases and so on?"
It is, Prof Dowdeswell says, "very difficult to put a percentage on that but my answer initially would be neither is it entirely natural nor is it likely to be entirely human- induced. Just where you put it on the scale between the two, I don't think anybody has the answer to."
The problem is that there is insufficient data to grasp the bigger, longer-term picture - 1979 and the start of the satellite era was a split second ago, in global eco-cycle terms.
"The interior of the Arctic basin wasn't really observed at all before the era of satellites, or only very, very rarely," says the professor.
The odd submarine pushed its nose up through the ice from the '60s onwards, but before that the only data was that collected by the likes of Franklin.
Of course, his last expedition produced nothing for the record. He'd been north before, leading a land expedition into the Arctic in 1819, although just how successful that attempt was can probably be gauged by the nickname he earned upon his eventual return to civilisation in 1823 when, in deference to his extraordinary tale of suffering and survival, the newspapers dubbed him The Man who Ate his Boots.
Nevertheless, the British navy nibbled away at the Canadian Arctic, from east and west, from the early 19th century until the 1880s, and Cambridge's Scott Polar Research Institute holds and has analysed many of the ships' logs from that period.
What they tell us, says Prof Dowdeswell, is that "the temperatures were about a degree or a degree and a half colder in the Canadian Arctic during those decades than they are today … that would fit with the view that the Arctic and other parts of the polar world suffered a little ice age for a few hundred years, to about the end of the 19th century".
Franklin, in other words, picked a bad century in which to tackle the frozen north.
"Not here," begins the verse written for his monument in London's Westminster Abbey by the Victorian poet Lord Tennyson, a relative of Franklin's by marriage. "The white north has thy bones."
Not for much longer, perhaps.