Leading article: Protect the polar bear, save the planet

The polar bear is under threat. In recent months the photogenic creature has become a symbol of the dangers posed by global warming. As Geoffrey Lean, our award-winning environment editor, reports from Greenland today, that threat is more urgent than hitherto feared. One fact alone from his report on page 6 should make us aware that the pointer on the global dial is entering the red zone. The Sermeq Kujalleq glacier is melting at a rate of 35 cubic kilometres a year.

We suspect that most of our readers, however, will not have been aware that polar bears are also shot by American trophy-hunters. The results of the investigation that we publish today reveal for the first time the extent of this distasteful leisure pursuit. It should come as no surprise that The Independent on Sunday believes that hunting polar bears for sport is wrong. People will not sit up and exclaim: "Look at this, dear, the Sindie is supporting John Kerry's bill." Indeed, Senator Kerry's attempt to ban the import of polar bear carcasses into the US from Canada is so readily endorsed by all right-thinking people that it has not been reported in the UK until today.

Human activity threatens the extinction of species at three levels. The first, and most direct, is hunting. Then there is direct habitat destruction by farming or construction. And finally there is the indirect threat from habitat loss caused by climate change, which in turn is mostly caused by humans. Of these, it is the last that is easily the most important. Polar bears have been hunted since the arrival of hunter-gatherer Homo sapiens; they have been part of the Inuit economy for as long as that society existed – admittedly a small part and mostly without high-powered rifles.

Western urban dislike of hunting should not distract us from the big issue – but it can be mobilised to guide people to it. Earlier this year, we reported that Zac Goldsmith, David Cameron's environment adviser, complained that it was easy to raise money to "save" particular animals – whales, pandas and now polar bears – but difficult to raise money to "campaign for increasing the fuel efficiency of cars to combat global warming... even though polar bears will not survive climate change".

That is plainly true, but he was wrong to imply that the "soft, feel-good things" somehow got in the way of the "grittier stuff". If people care about the fate of polar bears then it is not difficult to persuade them that the real threat to their survival does not come from hunters but from global warming gases produced by humanity's energy-hungry prosperity.

Nor is it hard to convert anger at the bloodlust of power-sled tourists into a more reasoned critique of the irresponsibility of shooting animals as their habitat melts beneath them.

Indeed, the ratchet effect of emotive symbolism is already working. Polar bears are likely to be listed in January as a "threatened" species under the US Endangered Species Act, based on a scientific assessment of the impact of global warming. This is one of many levers acting on the Bush administration's previous record of climate-change denial.

Unfortunately, this ratchet effect is working too slowly. Yesterday, for example, the US and Australia – both countries previously in the front ranks of climate-change scepticism – signed a declaration by the Asia-Pacific Economic Co-operation forum. "The world needs to slow, stop and then reverse the growth of global greenhouse gas emissions," it said. But the statement – like that issued by the G8 in June – did not commit to binding targets. It did not even promise to "consider", as the G8 richest nations did, the target of halving global emissions by 2050.

Geoffrey Lean's report brings home the inadequacy of even that target. Last week saw the peak week for ice melt in the Arctic – from now until next spring, the ice sheet will advance, before retreating again next year. But this year the ice has already retreated as far as the Intergovernmental Panel on Climate Change predicted it would retreat in 2050. The IPCC is no bunch of alarmist eco-warriors but a cautious committee of respected scientists operating by consensus and thus consistently erring on the side of playing down the danger.

In our "Planet in Peril" special edition last November, we featured a hypothetical news report, datelined 2030, of the death of the last polar bear in the wild. This campaigning journalism was criticised in some quarters as speculative, misleading or scaremongering. We disagree.

This newspaper is passionately committed to using any devices, however emotive and provided that forecasts are soundly based in science, that help to dramatise a long-term and somewhat intangible threat not just to polar bears but to much of life on the planet, including us. If it takes the sentimental tug of white fluffy animals, or our awe at the majesty of the world's largest land carnivore, to help jolt global opinion, so be it.