The Polar Regions: Sentinels of Major Climate Change

24 May 2005 - Articles, Logistics, Ice & Snow

Polar regions are not only keepers of the Earth's climate archives, They also act as sentinels. A kind of early warning system of what can be expected by the planet as a whole ...

Philippe Huybrechts is a glaciologist at VUB, the Free University of Brussels in Belgium. In two of his recent articles (published in the journals Nature and Geophysical Research Letters), he clearly demonstrated the current impact of global warming on Greenland. These two studies testifiy to the rapid thaw of the ice cap that covers this vast landmass between the Atlantic and Arctic Oceans.

"Polar regions are the first to suffer from global warming. But they also suffer more acutely than other parts of the world, both in terms of rapidity and intensity", he explains. "It is a question of albedo and temperature. In summer, when the Arctic sea ice melts, the surface of the water is darker and accumulates more solar radiation, thus accelerating the warming phenomenon. The same applies to emerged landmasses such as Greenland, northern Canada and southern Siberia, which have suddenly seen their snow cover disappear. On average, climate warming in these regions is two or three times more marked than elsewhere on the planet", explains the scientist. "The Antarctic, with the exception of its peninsula, currently appears to be protected from this kind of rapid disturbance, thanks to its better thermal "insulation", provided by the Antarctic Ocean".

Greenland is melting

The "disaster" scenario in the Arctic is no longer science fiction. What was initially only a question of modelling has since widely been confirmed by field observations, one example being changes to the Greenland ice sheet.

"Between 1950 and 1990, we saw a drop in Greenland's temperature of about 1.5°C", explains Philippe Huybrechts. "But since 1990, the temperature has been rising, and this has been exacerbated by a negative balance between precipitations in the region and melting of its ice sheet."

The result is that in a little more than ten years, the ice sheet has shrunk. Indeed, this phenomenon has amplified even further in the past five years. Huybrechts thinks that the situation is nearing a critical point.

"Each year, Greenland is losing about 80 cubic kilometres of ice (total ice sheet volume estimated at three million cubic kilometres). If the ice sheet loses 20% of its volume, the process will become irreversible", he suggests.

Sea levels are rising

The impact of this meltdown on the planet as a whole has resulted in rising sea levels. Each year, shrinkage of the Greenland ice mass causes a global rise of 0.2 millimetres. Over the past fifteen years, the rise has thus totalled 1.5 millimetres. If the phenomenon continues, i.e. if the global temperature of the planet goes on rising, the entire Greenland ice sheet will melt. Huybrechts reckons that the point of no return will be reached when the Earth's temperature has risen by 3 degrees. And if this rise reaches 10 degrees, Greenland will truly merit its name in a thousand years' time - a phenomenon which will also bring about a 7.5 metre rise in the level of the oceans!