Copenhagen Takes on Melting Ice

December 7, 2009

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Hello from Santiago, Chile, where the summertime temperature should be close to ninety degrees today; tomorrow it gets colder for me, heading across the Drake Passage in the early evening. As I’ve traveled for the past twenty-four hours of course the climate summit in Copenhagen is all over the news. While I am hardly a ‘climate skeptic’ – I firmly believe that the presence of 6.8 billion people on the planet and the pollutions we generate are adding to warming temperatures around the globe – I am skeptical of representatives of two hundred nations joining together to talk the subject to death having any immediate or even long-term effect. We have to hope, of course, but does anyone remember the modest goals espoused at Kyoto, none of which were ever met? From the start it’s been announced that anything agreed to in Copenhagen is … non-binding … which means what we may expect most from the confab is a lot of hot air.

Melting Arctic Ice

Since I’m heading to the iciest continent, it’s reasonable to start thinking about how Antarctica is changing and how it’s future impacts all of the world, particularly its ocean.

It is clear that the world’s ice is melting. Across the world more than 90 per cent of glaciers are retreating and thinning, mostly at an accelerating rate. (The exceptions are mostly in places where the melting has been compensated by increased snowfall – also a result of warming). In the tropics numerous glaciers have disappeared altogether. Most of the Himalayan glaciers could be gone by 2035, according to the IPCC, which is chaired by an Indian, though the forecast is contested by the Indian government.

The rapid melting is increasing summer river flows – but it raises the prospect that when the glaciers are gone, flows will diminish and depend entirely on the rains.

The same forces are at work on the planet’s giant continental ice sheets on Greenland and Antarctica, which together hold enough ice to raise sea levels by one hundred and eight feet. Greenland is losing around 250 billion tons of ice a year, enough to raise sea levels by three inches a decade. Antarctica is losing nearly as much, mostly from its vulnerable west side, which is perched on top of submerged mountains. Together, these ice sheets are currently responsible for less than half of sea level rise, which is currently at about eight inches a decade. (The rest is due to the expansion of effect of warmer ocean waters.)

Many glaciologists believe that within a few decades, the Greenland ice sheet may reach a point of no return, after which its near-total meltdown becomes inevitable. This is because as the ice sheet melts, its surface will be at ever lower altitudes, where the air will be progressively warmer, even if global warming ceases.

This melting process would take a thousand years or more. But there is growing evidence that things could happen more swiftly. Warming is creating giant waterfalls within the ice and rivers of water between the ice and bedrock beneath. Under this pressure, they say, the ice sheets could break up physically.

The dire predictions remain conjecture, but they explain why a series of studies in the past two years predict sea level rise could exceed a meter in the coming century – up to five times faster than previously estimated. Historical evidence shows that sea levels have risen this fast before – notably during the dying days of the last ice age. However there was a lot more ice around then.

Economists say rising sea levels are likely to be one of the most expensive consequences of global warming, requiring annual expenditure of $10 billion or more on sea defenses. Such estimates form the backdrop to Copenhagen talks on how much rich nations should contribute to help poor countries adapt to a changing climate.