It is a warning that, until very recently, governments throughout the world have chosen to ignore. Predictions about melting ice caps sounded like the stuff of science fiction and the consequences – rising sea levels and disastrous disruptions to global weather patterns - were just too fantastic to contemplate. The point Dr Macdonald and his colleagues make is that this highly sensitive region is of absolutely critical importance to the future, not just of Mankind, but of every living creature on Earth. The Arctic is a sentinel for the planet and the unprecedented changes that scientists have been observing there are pointers to what looks like an increasingly bleak future. There has been ice in the Arctic for at least 16 million years, but now average temperatures there are rising twice as fast as they are elsewhere in the world. The result is that Arctic ice is becoming thinner, melting and rupturing. For example, the largest block of ice in the Arctic, the 3,000-year-old Ward Hunt Ice Shelf, started cracking in 2000. Within two years it had split all the way through and is now breaking into pieces. The polar ice cap as a whole is shrinking at a rate of nine per cent each decade. According to data from NASA’s QuickSCAT satellite, between 2004 and 2005 the Arctic lost an unprecedented 14 per cent of its perennial sea ice – some 280,000 square miles (725,000 square kilometres), or an area the size of Texas.

Only a few years ago, climate modellers predicted the Arctic sea ice might disappear by 2100. They subsequently revised that prediction to 2070, then brought it forward again to 2050. Now, some scientists warn it could be as close as 2013. “It’s suddenly gone from being another generation’s problem to happening in my lifetime,” Dr Macdonald said. Over the past 20 years Dr Macdonald has observed a raft of extraordinary changes in the Arctic. “I remember the interior ocean when it was covered with bulk pack ice throughout the year,” he said. “Now we have an ocean that is only seasonally covered with ice. It freezes in winter, but it’s all firstyear ice that melts back out again in summer. We are now heading rapidly toward an Arctic Ocean that may be completely clear of ice in late summer every year. In the distant past the Arctic has seen quite abrupt natural climate change, but what we’re seeing now is quite different. There is exceptionally strong evidence that the critical factor driving these changes is CO2 gas emissions.” Dr Macdonald says the Arctic is warming at twice the average rate of the rest of the planet. The more the reflective surface of the bright white sea ice melts, he said, the more the dark Arctic Ocean absorbs sunlight, in turn melting more sea ice and feeding back into global warming. Rising temperatures are beginning to alter Arctic ecosystems: for example willows are replacing tundra in Alaska and, further south, the mountain pine beetle is devastating the forests of British Columbia.

There, warmer winter temperatures have helped the beetle to thrive: so much so that it is able to sneak in an extra generation each year. The result is that between 1993 and 2003, the beetles destroyed 3.4 million hectares of Alaskan forest alone. The melting of once permanent pack ice is already affecting the Arctic’s native people, the Inuit. When the Ward Hunt Ice Shelf splintered, the rare freshwater lake it enclosed, drained into the ocean. Polar bears, whales, walrus and seals, which have adapted to the long-term balance between first-year landfast ice and multi-year pack ice, have all been obliged to change their feeding and migration patterns, making it harder for the Inuit to hunt for their food. Arctic coastlines exposed to large expanses of open water are now so vulnerable to storms and rising sea levels that entire Inuit villages will have to be uprooted. The Inuit view global warming not only as a threat to their cultural identity, but to their very survival. Dr Macdonald explained the way in which rising temperatures in Arctic waters have the potential to change the survival equation for a vast array of creatures. “Take Arctic cod,” he said. “They have traditionally been widely distributed, keystone species foraged by seals, birds, narwals and belugas. In some places, cod have now been replaced by caplin, a fish species which has a different energy benefit for predators and in particular for marine birds. With changes like these, birds and other animals have had to switch their diets. Some can do it; some can’t do it so well. The point is that if you reduce the energy gain for the amount of foraging, you change the equation of survival. If birds then have to fly too far to get too little energy to feed their chicks, it may turn out in certain cases that those birds will have trouble surviving in their breeding colonies. That’s when we see those populations plummet.” As if that was not bad enough, Dr Macdonald also points out that where animals are nutritionally stressed, they begin to burn their fat reserves, releasing the raft of chemical contaminants like DDT or PCBs dissolved in their fat. Particularly since the 1950s, these contaminants have been entering the Arctic from the industrial and agricultural regions of the northern hemisphere surrounding the Arctic.

Nutritional stress plus contaminant exposure lead to vulnerability to viral attack or reproductive failure. Dr Macdonald cited the iconic Polar Bear as a prime example of an Arctic species that could be driven into extinction within a few decades. “Polar bears are seasonal feeders that depend upon the abundance of spring to fill up their gas tank,” he said. “During a critical two-week period in spring they gorge on the ring seals which pup on the ice and then they live off that fat for much of the year. When you change ice climate you can disconnect that feeding period. Even a subtle change of a few weeks in the presence of landfast ice can make the difference between whether these guys survive or not. They can respond to change by moving to places that are better for them, but of course there are pressures in those places already. “The Polar Bears down in Hudson’s Bay are in real trouble right now. Because it is at the southern margin of the Arctic, Hudson’s Bay is undergoing change sooner than the Arctic in general. Although it does have a complete ice cover in winter, the climate of the Bay has changed so much that the bears are often not getting the food they require. These guys are adapted for hunting on the stable platform of the ice. If you take that away, they don’t have sufficient elasticity in dietary choice to be able to switch to eating something else. If you take out their habitat, melt the permafrost containing their denning areas and take out their food sources then extinction is a definite possibility.” Dr Macdonald says the melting of the Arctic sea ice is also having a disastrous affect on coastal erosion. “In the Canadian Basin,” he said, “the ice retreats over 400 kilometres into the interior ocean so that you’ve now got long fetches of open water exposed to wind waves. Coastlines in that part of Canada are already under retreat because of permafrost melting and rising sea levels, but now when you throw in the fall storm surges and the large waves they can generate, you really accelerate that process. In the western Arctic, the shore-line in the Beaufort Sea is being eroded by 15 to 20 metres in some places, every year.” Dr Macdonald said there is now so much carbon dioxide in the atmosphere that scientists are growing increasingly concerned that the so-called “tipping point” for Greenland (the point at which the large ice cap becomes unstable and melts away) may not be all that far off. “We currently have something like 380 parts per million CO2 in the atmosphere,” he said. “And some models, together with palaeorecords, predict that if we go over something like 440 parts per million CO2 in the atmosphere we will lose the Greenland icecap.

We’re adding something like three parts per million per year, so in 20 or 30 years, if nothing is done, we will reach that tipping point. Melting of this ice, presently stored on land, would result in about six metres of sea-level rise globally. Think about the implications of that for low-lying places like the Netherlands, Bangladesh, the Bohai Peninsula in China, the state of Florida and many of the islands in the Pacific Ocean. These places are going to be in very serious trouble. This is the point that we have to drive home to governments around the world. You know, when shocks like this come upon us, the initial reaction is denial. We deny it’s happening and we deny that we are responsible for it. Eventually when enough people get angry something will be done.…I hope.” Although this rather depressing evidence of the way in which we are fouling our own nest might seem like a recipe for despair, Dr Macdonald says he remains optimistic. “There is a temptation,” he said, “to throw your hands up and say, ‘it’s too late…we can’t do anything about it’, but I think that’s a copout. I don’t think it is too late. This generation needs to start doing things about it: things that may be uncomfortable and may cost us a bit, but frankly any pain we may suffer now will be nothing compared with what we will endure if we do nothing. “We are going to have to do two things here. One is we are going to have to adapt. Like it or not, some of these changes are going to come. We are going to have to do something about conserving fuel and not putting CO2 in the atmosphere. That will help soften our transition into sustainable energy sources.

We simply have to stabilise CO2 levels in the atmosphere. We cannot continue to allow them to go up and up. The second thing is that the developed world, the Western world, is going to have to show some leadership here. We are going to have to do that before we can convince developing countries like India and China that they ought to play their part.” Dr Macdonald points to the enormous significance of the fact that in his own lifetime the Arctic Ocean has gone from being one of the world’s most hostile natural environments to a place which now offers “a viable public transport corridor for two months of the year”. The great Arctic meltdown is now prompting leading Arctic nations like the United States, Canada and Russia to seriously examine new shipping routes – including the fabled North West Passage – and the potential expansion of huge new oil and natural gas fields. “All this talk about opening up the resources of the Arctic misses the point,” Dr Macdonald said. “The Arctic is a sentinel for the rest of the planet. The changes happening up there are changes that will ultimately affect everyone of us.”