Greenland ice sheet may melt completely with 1.6 degrees global warming

In 2,000 years.

The media release is below.


Contact: Mareike Schodder
Potsdam Institute for Climate Impact Research (PIK)

Greenland ice sheet may melt completely with 1.6 degrees global warming

The Greenland ice sheet is likely to be more vulnerable to global warming than previously thought. The temperature threshold for melting the ice sheet completely is in the range of 0.8 to 3.2 degrees Celsius global warming, with a best estimate of 1.6 degrees above pre-industrial levels, shows a new study by scientists from the Potsdam Institute for Climate Impact Research (PIK) and the Universidad Complutense de Madrid. Today, already 0.8 degrees global warming has been observed. Substantial melting of land ice could contribute to long-term sea-level rise of several meters and therefore it potentially affects the lives of many millions of people.

The time it takes before most of the ice in Greenland is lost strongly depends on the level of warming. “The more we exceed the threshold, the faster it melts,” says Alexander Robinson, lead-author of the study now published in Nature Climate Change. In a business-as-usual scenario of greenhouse-gas emissions, in the long run humanity might be aiming at 8 degrees Celsius of global warming. This would result in one fifth of the ice sheet melting within 500 years and a complete loss in 2000 years, according to the study. “This is not what one would call a rapid collapse,” says Robinson. “However, compared to what has happened in our planet’s history, it is fast. And we might already be approaching the critical threshold.”

In contrast, if global warming would be limited to 2 degrees Celsius, complete melting would happen on a timescale of 50.000 years. Still, even within this temperature range often considered a global guardrail, the Greenland ice sheet is not secure. Previous research suggested a threshold in global temperature increase for melting the Greenland ice sheet of a best estimate of 3.1 degrees, with a range of 1.9 to 5.1 degrees. The new study’s best estimate indicates about half as much.

“Our study shows that under certain conditions the melting of the Greenland ice sheet becomes irreversible. This supports the notion that the ice sheet is a tipping element in the Earth system,” says team-leader Andrey Ganopolski of PIK. “If the global temperature significantly overshoots the threshold for a long time, the ice will continue melting and not regrow – even if the climate would, after many thousand years, return to its preindustrial state.” This is related to feedbacks between the climate and the ice sheet: The ice sheet is over 3000 meters thick and thus elevated into cooler altitudes. When it melts its surface comes down to lower altitudes with higher temperatures, which accelerates the melting. Also, the ice reflects a large part of solar radiation back into space. When the area covered by ice decreases, more radiation is absorbed and this adds to regional warming.

The scientists achieved their insights by using a novel computer simulation of the Greenland ice sheet and the regional climate. This model performs calculations of these physical systems including the most important processes, for instance climate feedbacks associated with changes in snowfall and melt under global warming. The simulation proved able to correctly calculate both the observed ice-sheet of today and its evolution over previous glacial cycles, thus increasing the confidence that it can properly assess the future. All this makes the new estimate of Greenland temperature threshold more reliable than previous ones.

Article: Robinson, A., Calov, R., Ganopolski, A. (2012): Multistability and critical thresholds of the Greenland ice sheet. Nature Climate Change [doi:10.1038/NCLIMATE1449]

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9 thoughts on “Greenland ice sheet may melt completely with 1.6 degrees global warming”

  1. The next glacial – not according to the alarmists who claim there are already enough GHGs “up there” to stave off the next glaciation – boy I hope they’re right – I don’t want all you northerners migrating to sub-tropical Australia to escape the advancing glaciers – oh wait, they don’t actually advance very quickly do they ?

    I cannot believe these people have the true situation completely backwards.

    Our atmosphere acts to reduce the solar heating of the surface – it does not add heat.

    If we didn’t have an atmosphere the Earth’s surface would actually be much hotter than currently – what proof is there for this outlandish statement ??

    Well, the same solar radiation heats the Moon from misus ~200 degrees C to over ~120 degrees c. True, the lunar day is some 29 Earth days BUT this does not mean the high temperature is because of this – rather it proves the long night is why the Moon’s surface cools so much.

    If the Earth had no atmosphere the surface would not cool as much – by a long way – over 12 hours and next day the Earth would be subject to the solar radiation and would quickly heat up to much more than the minus temperatures on the Moon and quite rapidly approach the temperature associated with the solar radiation NOT as a maximum but as an average.

    Any idiot can see the atmosphere actively reduces the heating effect of the solar radiation if they think about – water enhances the cooling effect by evaporation.

    Radiation is not the dominant method of energy transfer in an atmosphere – it simply provides the final escape to space !

    What prrof is there radiation is NOT a dominant form of energy transfer in an atmosphere ??

    Vacuum flasks !

    Even though the exterior of these devices is metal they slow energy loss by many orders of magnitude by simply inhibiting direct conductive heat loss.

    If there were a “greenhouse effect” as these fools postulate then CO2 flasks would be the flask of choice, vehicle radiators would actually cool by radiation instead of convective cooling, ovens would NOT benefit from “fan forcing” etc etc etc.

  2. Melting the Greenland icecap would take longer than Homo Sapiens has been Homo Sapiens. That puts the concern in perspective, as merely the caterwauling of Chicken Littles.

    Long before in a few thousand years, we will enter the next glacial period and depart the brief Holocene interglacial period.

  3. We used to say: ” Lord save us from the inquisition.” Now it’s “Lord save us from the climatites.”

  4. There’s something wrong with more arable land?

    Oh, noes, we might be able to farm Greenland !!!

  5. And when the ice melts, the archaeologist’s will go bonkers digging in the ancient viking ruins.

  6. May. May not. May grow if increased snow and ice is caused by open Arctic waters. Whatever. Here’s to Greenland developing Greenland if they can get to Greenland under all that ice. Venice subsides anyway.

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