During scientific debates, the floe breaks up

By Denis Delbecq • September 5th, 2008 in 14:38 · Category: Actuality

The rise of the oceans is a reality. From there to envisage the largeness of phenomenon, science remains still very imperfect. Until now, the consensus of the scientists made responsible by the UNO for making the state of knowledge on climate, within GIEC (1) was made on a fork from 18 cm to 59 cm of increase before 2100. But recent many studies envisage an increase which could exceed two metres. What would cause the swallowing up of more sprawling lands and multiply the number of displaced persons.

This week, several contradictory signals came to complicate deal a bit. Today, in Science, researchers of the American University of Boulder (Colorado) move forward an including fork enter 0,8m and 2m, thinking that he and very unlikely that the increase in the oceans could be more important. The researchers tried to determine which quantity of water of cast iron of the skull caps of Greenland and of Antarctic would be necessary so that the level of seas goes up of two metres, also by taking into account the increase linked to the increase of the temperature of the water, which causes a widening of the liquid. Then, the American researchers compared this quantity of water to the rhythm of disappearance of these glacial skull caps. They conclude from it that, in current pace, the increase in the level of the oceans should not exceed two metres.

However, the team of Boulder will perhaps have to do again its calculations. Because last Sunday, in Nature Geoscience, another American team, of the University of Wisconsin, showed that the glacial skull caps can melt much more quickly than envisaged. While they consider that the disappearance of a skull cap several kilometres thick becomes on the scale of millenniums, Anders Carlson and his colleagues show that the carrot slaps Laurentides, which covered the most part of North America twenty thousand years ago knew two periods of breaking up of only the five centuries and of the eight centuries, 9000 years and 7600 years ago. The first epoch would have made take up the 1,3-metre oceans by century, and the 0,7-metre second by century Rest to be known now if this type of event perhaps generalised in a region as that of Greenland, from which physiognomy and environment very differ. Carlson thinks that yes, unlike two colleagues who, in a comment published in the same number of Nature Geoscience, remind that Greenland resisted last déglaciation while the skull cap of Laurentides disappeared …

Until debate is settled, the ice of the Arctic continues melting. According to the American Centre of data on the snow and the ice (NSIDC), record breaking up recorded in August continues, and the surface of Arctic floe goes up very close to the record of minimums recorded last year, letting think that he will be able to be before beaten mid-September, when the arrival of the autumn will make re-freeze the ocean. Besides, in August, the floe of Markham, in the Canadian north of the Arctic broke up, liberating a 55-kilometre block square compelled to split and to drop thousands of icebergs compelled to melt. In the region of Serson, it is 120 km2 of the ice that parted from some floe and started the drift. An ice which, since she has floated already, will not draw away a well-blended time of rise of the level of the oceans.

For the Canadian researcher Warwick Vincent, questioned by Reuters on September 3rd, it is a sign of the acceleration of warming in the Arctic. He determined a breaking up ten times as sprawling as what he had prognosticated for this summer. The temperature sometimes attained 19,7 degrees in the region of Markham, against a summer average of 8 degrees …

(1) Intergovernmental group of experts on climate.

• To know more about it, notice the effect of a rise of the oceans on the scale of the planet on our simulator.

• Participate in our grant of forecasts on the minimal surface of floe in the Arctic.

Picture: © Denis Delbecq

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