From the Max Planck Institute for Meteorology: Climate changes faster in the Arctic than anywhere else on Earth, a phenomenon that is often explained by retreating snow and ice leading to more solar surface warming (positive ice-albedo-effect).
In a new study in Nature Geoscience the scientists Felix Pithan and Dr. Thorsten Mauritsen from the department “The Atmosphere in the Earth System” at the Max Planck Institute for Meteorology show that this effect is only secondary. Instead, the main cause of the high Arctic climate sensitivity is a weaker temperature feedback, due to 1) the low temperatures that prevail and 2) the increasing temperatures with height trapping warming to remain near the surface. For these reasons, the Arctic warms more in a global warming due to a forcing from e.g. CO2 than other regions.
Some commentary sheds further light on this.
NoTricksZone points out that the German Newspaper, Spiegel, writes:
To balance out the radiation budget at an ambient temperature of 30°C, an increase of 0.16° is enough. However at minus 30°C, an increase of 0.31 °C would be needed, i.e. almost double, which gives Pithan und Mauritsen cause for thought. According to their calculations the lower start temperature in the Arctic is an important reason for the more rapid temperature increase in the Arctic compared to the tropics.”
They found that the surface albedo feedback is only the second main contributor to Arctic amplification, and that other contributions are substantially smaller or even oppose Arctic amplification.
This casts many of the assumptions made in earlier climate models deep into doubt. It’s back to the drawing board (again) for the modelers.
- See more at: http://notrickszone.com/#sthash.K8HUQkuu.dpuf
Arctic amplification dominated by temperature feedbacks in contemporary climate models
Felix Pithan & Thorsten Mauritsen
Nature Geoscience (2014) doi:10.1038/ngeo2071 Received 25 November 2013 Accepted19 December 2013Published online 02 February 2014
Climate change is amplified in the Arctic region. Arctic amplification has been found in past warm1 and glacial2 periods, as well as in historical observations3, 4 and climate model experiments5, 6. Feedback effects associated with temperature, water vapour and clouds have been suggested to contribute to amplified warming in the Arctic, but the surface albedo feedback—the increase in surface absorption of solar radiation when snow and ice retreat—is often cited as the main contributor7, 8, 9, 10. However, Arctic amplification is also found in models without changes in snow and ice cover11, 12. Here we analyse climate model simulations from the Coupled Model Intercomparison Project Phase 5 archive to quantify the contributions of the various feedbacks. We find that in the simulations, the largest contribution to Arctic amplification comes from a temperature feedbacks: as the surface warms, more energy is radiated back to space in low latitudes, compared with the Arctic. This effect can be attributed to both the different vertical structure of the warming in high and low latitudes, and a smaller increase in emitted blackbody radiation per unit warming at colder temperatures. We find that the surface albedo feedback is the second main contributor to Arctic amplification and that other contributions are substantially smaller or even oppose Arctic amplification.