15 júla 2008

GW Science: Úbytok ľadu v Grónsku nerastie

Pre aktivistov globálneho otepľovania je ľad v Grónsku významným argumentačným arzenálom pre potvrdenie tézy, že s klímou Zeme sa "niečo deje" (a to "niečo" musí byť zákonite spôsobené človekom). Podľa štúdie autorov pod vedením Roderika S.W. van de Wala z Institute for Marine and Atmospheric Research of the University of Utrecht, ktorá bola publikovaná v ostatnom vydaní prestížneho Science, rýchlosť ropenia ľadu v Grónsku prestala akcelerovať a reálne môže začať v dlhodobom meradle klesať.

Článok v Science (link)
R. S. W. van de Wal,* W. Boot, M. R. van den Broeke, C. J. P. P. Smeets, C. H. Reijmer, J. J. A. Donker, J. Oerlemans: Large and Rapid Melt-Induced Velocity Changes in the Ablation Zone of the Greenland Ice Sheet
Continuous Global Positioning System observations reveal rapid and large ice velocity fluctuations in the western ablation zone of the Greenland Ice Sheet. Within days, ice velocity reacts to increased meltwater production and increases by a factor of 4. Such a response is much stronger and much faster than previously reported. Over a longer period of 17 years, annual ice velocities have decreased slightly, which suggests that the englacial hydraulic system adjusts constantly to the variable meltwater input, which results in a more or less constant ice flux over the years. The positive-feedback mechanism between melt rate and ice velocity appears to be a seasonal process that may have only a limited effect on the response of the ice sheet to climate warming over the next decades.
Michael Asher na DailyTech.com (link)
However, a new study has concluded that Greenland's rate of melting is not accelerating, and in fact may actually be decreasing when viewed over a longer timescale. The study, which used 17 years of satellite measurements to reach its conclusions, determined the overall yearly movement of ice to the sea is not increasing, and is actually decreasing in some places.

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