This is a memorable and important book about a magnificent animal that now seems doomed to die before our very eyes, while we who are responsible for its passing stand by in melancholy amazement, almost mute.
However, all is not quite lost. Even at this late stage, there is a slender chance that regulations could still be enacted that would help stay the bears' demise - perhaps even prevent it. Currently, those in Barack Obama's White House and other corridors of northern power seem hesitant to do so.
Richard Ellis, reigning poet laureate of the marine world, appears on the strength of this impeccably argued and fact-filled treatise on the history and present standing of Ursus maritimus to be the perfect candidate to help persuade them to do the right thing.
I have had three memorable encounters with polar bears, each in its own way emblematic both of their regard and of their fate, which are so painstakingly outlined in On Thin Ice. The first was when I was small, and my mother took me to the London Zoo to join the endless lines of schoolchildren taken to see a newborn cub named Brumas.
In the drab and battered impoverishment of postwar London, so adorably comforting a creature cheered us all up mightily. Yet Brumas was to be the unknowing precursor of a vast industry that would soon be constructed around the immediately recognizable cuteness of small white bears, and which would be exploited by legions of toy makers, by the Coca-Cola Corporation, by Hollywood and by countless other zoos - most notably in recent years, Denver, with Klondike and Snow, and then, more recently, by Berlin, with an exceptionally handsome male cub born in 2006, and named Knut.
Knut proved to be both the apotheosis and nemesis of cute, providing in his swift rise and fall his own set of highly contemporary emblems of ursine tragedy. He was visited by millions, in person or on Facebook. He appeared on postage stamps and an entire world of magazine covers, culminating in his being photographed by Annie Leibovitz, and photo-shopped with Leonardo DiCaprio onto the cover of Vanity Fair.
But then he grew up and angered people by growing ragged and turning a dirty yellow colour, then going horribly mad and a little savage - at which point lawyers were unleashed to try claw away much of the money he had made back in the days when he was cute. The case continues, while Knut remains alone and unvisited, looking as bitter as only an unkempt and jaundiced bear can.
My second encounter was in 1965, when I shot a polar bear and ate it. It was in East Greenland, I was on an expedition that was trapped and had run out of food; we had radioed permission from Inuit hunters in a settlement nearby. It was an elderly bear, and its muscles turned out to be infested with enormous flatworms, rendering it not especially good to eat. I have never shot an animal since. But some Inuit still do: To a hungry family in the Arctic North, the idea of prettiness runs a distant second to poundage. The public attitude to the 22,000 polar bears that Richard Ellis estimates remain depends very much on where and how that public lives.
And the third encounter came 10 years ago, in the far north of Ellesmere Island. I was then on another expedition, a pair of us trekking from Cape Sabine to Lake Hazen, fretting over the Parks Canada rule forbidding the carrying of rifles. What if we came across a bear? I wondered. Well, we did - and they proved the gentlest and most polite of animals, keeping solemnly aware of us at all times, circling, sniffing the air, watching us day after day as we trekked on - but never once making any kind of threatening move.
Which is something that Richard Ellis is at pains to remind us: that polar bears are seldom aggressive in the wild, and the popular image of their ferocity has been contrived largely to justify either their hunting - for the 20th-century rich, with their helicopters and Nitro Expresses, the animal was very much the Great White Hunted - or their enslavement in circuses and entrapment in zoos. In captivity - but only in captivity - they do frequently turn nasty: Bears in New York have killed at least twice, and one in Central Park bit off the finger of a youngster who was trying to feed it a peanut.
But now they are the threatened ones. The warming of the world is steadily reducing to slivers the territory that these highly evolved creatures have been designed to occupy. There is no possibility they can now backtrack, that they can turn brown and become once again the grizzly bears from which they are descended: Biological law determines they will never be able to adapt to feeding on the salmon and berries that are now invading their shrinking world of floes and seals. Grizzlies may well come to the live in the balmier climes of the High Arctic; but if the High Arctic warms up, then polar bears will simply vanish. It is as devastating and stark as that.
The only chance for the bears - or our only chance, for it is not entirely cynical to remember that the preservation of the world's animals and environment is largely designed for the benefit and pleasure of humankind - is if global warming is reversed, and quickly. Cutting back human reliance on carbon-emitting fossil fuels is one all-but-proven way to do this - which is why the current furious debate on drilling for oil on the Arctic continental shelf has both practical and a symbolic implications - for polar bears in particular, and the world as a whole.
All are currently waiting for Washington to make up its mind on this single, but highly symbolic issue. Will the officials there act to take a serious step to ending humankind's century-long dependence on oil by banning the drilling - and help reduce the perils to polar bears at the same time? Or will President Obama's appointees bow to the greater gods of Shell and Exxon, take the altogether easier step in the other direction, and allow the rigs and the pipelines to invade?
It is but a faint hope that all the makers of policy in the U.S. Department of the Interior, the body designated to make this fateful choice, might be given copies of this splendid book for Christmas. It should help make up their minds, once and for all.
Simon Winchester's Atlantic: A Biography of the Ocean will be published next fall..