Great summary again, Neven! By the way, we have a new reference to cite for the AMSR2 sea ice concentration data: Beitsch, A.; Kaleschke, L.; Kern, S. Investigating High-Resolution AMSR2 Sea Ice Concentrations during the February 2013 Fracture Event in the Beaufort Sea. Remote Sens. 2014, 6, 3841-3856. Available for free at http://www.mdpi.com/2072-4292/6/5/3841

"Millikan measured the charge on an electron by an experiment with falling oil drops, and got an answer which we now know not to be quite right. It's a little bit off because he had the incorrect value for the viscosity of air. It's interesting to look at the history of measurements of the charge of an electron, after Millikan. If you plot them as a function of time, you find that one is a little bit bigger than Millikan's, and the next one's a little bit bigger than that, and the next one's a little bit bigger than that, until finally they settle down to a number which is higher. Why didn't they discover the new number was higher right away? It's a thing that scientists are ashamed of - this history - because it's apparent that people did things like this: When they got a number that was too high above Millikan's, they thought something must be wrong - and they would look for and find a reason why something might be wrong. When they got a number close to Millikan's value they didn't look so hard." (Feynman, 1997) from http://www.columbia.edu/~jeh1/mailings/2012/20121226_GreenlandIceSheetUpdate.pdf Seems to be a related phenomenon

NeilT, those images are located north of Svalbard. I thought you meant the Canadian Archipelago. On your MODIS selection you can clearly see a divergent ice cover, single ice floes and open water, and probably not many melt ponds.

Uni Bremen AMSR2 is showing significant open water in the CAB. I wonder if this really is or if it is only melt ponds. From the blueish colors in the MODIS arctic mosaic you can infer that this is the effect of meltponds. http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r04c01.2013162.terra See also http://www.seaice.de/Roesel_IEEE_2012.pdf

Here you find some good information about the enhanced weathering method. Although it might sound good at a first glance, reducing the ocean acidification and removing CO2 from the atmosphere at the same time, it seems not to be a suitable treatment. http://www.awi.de/en/news/press_releases/detail/item/how_much_carbon_dioxide_can_be_removed_from_the_atmosphere_if_the_mineral_olivine_is_increasingly_de/?cHash=1c8ec116a73b9819ace4ed1873bfd19b

Chris, you are absolutely right! Don't take the SMOS ice thickness as absolute value. There are large uncertainties and the thickness has always a low bias if there is thick ice (>0.5m) in the field of view. By the way, you point to the 2012 GRL paper, not to 2010. This can be found here: http://www.the-cryosphere.net/4/583/2010/tc-4-583-2010.pdf In this paper you find in the conclusions: "We suggest that the retrieval should be interpreted as a lower boundary of the thermodynamic (i.e., modal or level) ice thickness." With SMOS you can not distinguish if the ice is 60 centimeter or 6 meter thick because of the saturation of the emissivity (see Fig 1). As an example, have a look at http://www.arcus.org/files/search/sea-ice-outlook/2011/07/images/pan-arctic/image009.png There you see the so called "modal thickness" is about 3 meter but the average thickness is larger because of the shape of the distribution. Unfortunately, the press release has not stressed the uncertainties. Here is some text which became not part of the press release: "It has been shown that the measured L-band brightness temperature can be clearly related to the sea ice thickness for ice not thicker than half a meter. However, since it is not a direct measurement of thickness and the algorithm includes several assumptions, there are potential uncertainties. At first, the retrieval is influenced by open water and leads within ice cover. Because we assume a 100% closed ice cover, the ice appears to be thinner if open water is present. Secondly, the brightness temperature is influenced by changes of the ice temperature and bulk salinity. Thirdly, the brightness temperature is influenced by a snow layer on the sea ice. Despite the remaining uncertainties with respect to the absolute SMOS thickness, we can state that Arctic sea ice became significantly weaker between the years 2011 and 2012." So, please be careful with the interpretation and comparisons to other data. Sea ice thickness is not always the same sea ice thickness. There are many thicknesses: mean thickness, modal thickness, effective thickness, and now we also have the "SMOS thickness". You have to take it qualitatively until we have more validation data which are very sparse. Lars

Here is another video on ice thickness. Watch out for the upcoming ESA webstory: http://www.klimacampus.de/fileadmin/user_upload/klimacampus/6_Visualisierung/Ice_Thickness_KlimaCampus__Uni_Hamburg__ESA__Planetary_Visions.mov

Have you seen the little "polynya" that emerges at about the same position as last summer? Interesting times for sea ice research... http://www.klimacampus.de/631+M57991a9bc34.html?&L=1