DThe ice is three kilometers thick at the highest points, and a tenth of the entire freshwater supply on earth is stored here, close to the North Pole, in a frozen state. And yet this mighty white shell seems as fragile to its visitors as soft ice cream in the blazing sun. The ice is melting faster and faster, everywhere. Until the end of the 1990s, no clear warming trend could be seen on the highest points in the central highlands of the world’s largest island, but it is now clear that climate change has already pushed the temperature up to alarming levels on the ice peaks. Already in the decade between 2001 and 2011, the temperature anomaly up there was 1.5 degrees above twentieth-century levels – above average on a global scale.
“Global warming is reaching the middle of Greenland”, was the headline a few weeks ago of a team of glacier researchers from the Alfred Wegener Institute (AWI) in Bremerhaven, which published the latest findings from ice core analyzes in the journal “Nature”. The warming at the beginning of the millennium clearly differs from the natural fluctuations of the last thousand years. “We feared that in view of global warming, but the clarity and conciseness is unexpected,” said AWI glaciologist Maria Hörhold, commenting on the evaluation of the drill cores, which were backed up with satellite data and findings from climate models.
What was already apparent back then has now become established: Greenland reacts extremely sensitively to global warming. Also different from the surrounding regions in the Arctic, which is due to the influence of the high-altitude ice fields on the atmospheric circulation. “Our reconstruction shows its own dynamics,” says Thomas Laepple, climate researcher at the AWI. In addition to the melting and climate data from the ice archives, the calculations of other climate researchers also give an idea of how special the development in Greenland is and could become.
255 billion tons of meltwater annually
Dennis Höning from the Potsdam Institute for Climate Impact Research has just presented a new simulation of Greenland’s development in the journal “Geophysical Research Letters”, the complexity of which goes far beyond the previous models. Both the climate and ocean dynamics of the entire earth and important processes such as those under the Greenland ice were physically described in comparatively high resolution. The result amazed the research group. With its exorbitant rate of ice melt, Greenland is obviously not heading for one, but for at least two crucial tipping points.
The geophysical tipping elements are elements in the earth system which, once certain values have been exceeded, no longer gradually continue to change – melt here – but abruptly and accelerated and then, above all, irreversibly head towards a new equilibrium value.