Monday, February 7, 2011

Max Plank Institute Findings Show “Arctic Tipping Point Improbable”

The drop in Arctic sea ice in the last years caused many to fret over a possible tipping point, after which melting would be unstoppable.  
However, new findings from the Max Planck Institute for Meteorology show this is highly unlikely. What follows is the Press Release in English:
Hope for the Arctic sea ice
Recent finding show that there is no no such a tipping point for the loss of Arctic summer ice. Instead the ice area responds relative to the climatic conditions at hand. The ongoing loss of Arctic sea ice could slow down or even stop when global warming slows down or stops. Steffen Tietsche, lead author in the study published this by Geophysical Research Letters [1], said he was at first quite surprised by the findings:
‘The possible existence of a tipping point first appears to be completely logical: When the ice cover retreats, the sea water absorbs more sunlight and so it warms up even more, and more ice melts. Such a feedback in priciple leads to an amplification of the Arctic sea ice melt and thus make it independent of the prevailing climate conditions.’
The scientists examined the validity of this concept with a climate model. In this model they completely removed the Arctic ice cover at the beginning of summer in order to maximise the absorption of sunlight by the open water.
‘Indeed we expected that the Ocean would remain ice free after the modelled ice melt because the open water takes up more warmth in the summer,’ said Tietsche. But unexpectedly, the ice sheet always recovered in the model simulation within three years so that the conditions that prevailed before the modelled ice melt were again re-established. These results indicate that the condition of the sea ice is closely connected to the prevailing climate conditions, thus making a tipping point improbable.
The scientists discovered the process that allows the recovery of ice: During the winter, the ocean loses most of the heat absorbed during the summer. Becauseof the missing ice that otherwise would serve as an insulator, heat loss becomes very efficient as the open ocean is in direct contact with the cold atmosphere. In addition the very thin ice grows very quickly because it is more poorly insulated than thick ice. The heat that is given from the ocean through the thin ice then leads to a stronger thermal radiation by the atmosphere into space and also to a reduced heat transport from the south into the Arctic.
The combination of these two stabilizing feedbacks is stronger than the destabilizing feedback from the additional absorption of sunlight by exposed water in the summer time. The study by the Max Planck scientists confirms research conducted by US scientists using a much simpler model [2].
This model agreement of two completely different levels of complexity usually means that the results are reliable,’ says Jochem Marotzke, Director at the Max-Planck-Institute and co-author of the new study.
[Now comes the MPI religious confirmation of AGW belief - necessary for further funding]
The scientists emphasize that their findings do not question the dramatic loss of Arctic sea ice because of man-made climate change. ‘If we do not greatly slow down global warming, then the Arctic will be ice-free in the summertime in a few decades,’ says Tietsche. ‘Our research shows that the speed at which the sea ice is retreating is closely related to the rate of global warming. Our work does underscore, however, that we can still slow down and even stop the loss of Arctic sea ice.’ “
Firstly, forget the scary tipping points. The laws of thermodynamics and heat transfer say it isn’t possible. The tipping point was the figment of alarmist scientists’ imaginations gone wild. That we pretty much knew already. Secondly, the temperatures in the Arctic govern the melting and freezing of the ice. If the globe cools naturally, then the ice will recover. And thirdly there’s no new data to show that CO2 is the cause of the recent Arctic melt. Remember, the last 30 years show the opposite in Antarctica.
[1] Tietsche, S., D. Notz, J. H. Jungclaus, and J. Marotzke (2011), Recovery mechanisms of Arctic summer sea ice, Geophys. Res. Lett., 38, L02707, doi:10.1029/2010GL045698.
[2] Eisenman, I., and J. S. Wettlaufer (2009), Nonlinear threshold behavior during the loss of Arctic sea ice, Proc. Nat. Acad. Sci. U. S. A., 106(1), 28–32, doi:10.1073/pnas.0806887106.

No comments:

Post a Comment