Important legal notice
   
Contact   |   Search   
RTD info logoMagazine on European Research Special issue - May 2005   
Top
 HOME
 TABLE OF CONTENTS
 EDITORIAL

Download pdf de en fr


Title  The polar regions: sentinels of major climate change 

The polar regions are not only the 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…

Elephant Foot Glacier, at around 81° N along the east coast of Greenland. The grey zone at low elevation is the ablation zone incised by meltwater channels, clearly separated from the white surface accumulation zone higher up.
Elephant Foot Glacier, at around 81° N along the east coast of Greenland. The grey zone at low elevation is the ablation zone incised by meltwater channels, clearly separated from the white surface accumulation zone higher up.
© P. Huybrechts/VUB
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 testify to the rapid thaw of the ice cap that covers this vast landmass between the Atlantic and Arctic Oceans.

"The 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 been widely 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 3 millimetres. If the phenomenon continues, i.e. if the 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!

Satellite images, available since 1979, have shown an increasing trend in seasonal surface melt extension of the Greenland Ice Sheet at the height of summer.
Satellite images, available since 1979, have shown an increasing trend in seasonal surface melt extension of the Greenland Ice Sheet at the height of summer.
© Clifford Grabhorn, 2004, ACIA/Map

Printable version

Features 1 2 3 4 5 6 7
  The polar regions: sentinels of major climate change 
  Polar flora and fauna facing up to major climate warming
  The peoples of the Arctic, the first victims of global warming
  And what would happen if the Gulf Stream stopped?
  Ozone story
  Satellites at the service of polar research
  Permanent monitoring of the atmosphere from the Svalbard


  TO FIND OUT MORE  
 
  • Geophysical Research Letters, vol. 31, L24402; Greenland Ice sheet: increased coastal thinning.
  • Nature, vol. 428, p. 616.
  •  


       
      Top
    Features 1 2 3 4 5 6 7

    TO FIND OUT MORE

    • Geophysical Research Letters, vol. 31, L24402; Greenland Ice sheet: increased coastal thinning.
    • Nature, vol. 428, p. 616.

    CONTACTS