Hot from the press: The latest prediction frm NOAA. http://onlinelibrary.wiley.com/doi/10.1002/grl.50316/abstract

I am a scientist and I am very familiar with the political process. Your are perfectly right about the way risk should be managed. Very basic classical risk management technique would have tells you 20 years ago to take action to reduce greenhouse gases. Also, the same basic management tools would have tell you that that the best strategy would be to plan something closer to the worst case than the middle case. However, apart of been risk adverse humans have very much trouble to NOT discount the future. Many people dot care what will happen in a 20 years time frame, even less in an 100 years one. And many more, are wondering how they will close to month. We are just psychologically blind to that type of risks. Politics only reflect that. The secret hope of many people like me who work in energy is that we will exhaust the fossils fuel before it is too late. Otherwise, I don't we could manage this issue.

Well, as a scientist, you don't want to overestimate. If you overestimate,the accusation of exaggerating will follow immediately and your message will be lost. From a political point of view, conservatism is the safest path.

Crandles, a spagetti plot made from this year trajectory combined with all the previous decay trajectory would be visulay interesting.

James, this is scary. In the arctic, deep water is warmer than surface one. If it manage to go past the grounding line, we may see the whole glacier retreats at flank speed.

Steve, your point about albedo is a common assumption but it is wrong unless you deal with a greybody. If you a difference between spectral bands the result will different. I can tells you the story of a company that was selling very good blackbody in thermal IR, but nobody wanted to buy them because they were green at visible wavelength. If I remember correctly, snow is pitch black from NIR to end of the spectrum due to the strong absorption band of the water and texture of the snow that behaves like a photon trap. On the positive point. If enough dirt accumulate over snow the whole process will slow down as the dirt will act as an insulation layer, lime we see in spring on highways sides in Canada.

A complement of information hot from the press: http://www.sciencedaily.com/releases/2012/06/120626065007.htm

@Jon Torrance Their method is effectively very unstable now. If you check their graph, the slope is dominated by one data point: 2007. From what I have seen, this mostly the case all the time. Anyway, from their own data their predictor is essentially worthless before June. ftp://ftp-projects.zmaw.de/seaice/prediction/2012/prediction_timeseries.png

Naive is not the right adjective. Least square fitting are the most effective way to extract information from data (assuming a Gaussian distribution). Hence, your model is very sound. In theory, you could push thing further by examining the relationship between residual observed in September and residual observed sooner in the year. I think that at least one group is using a similar technique (Bremen?)

Karl, CO2 is a greenhouse gas and is bound to increase temperature. This not a theory, not a paradigm, this is a fact. Anybody who have seen a IR spectra of the atmosphere known it first hand. Only the magnitude of the effect can be argued. And, yes the Sun effect has been checked. Indeed, it has been examined for 200 years. Climate science is born form this study. And, yes, the effect exist but it is small.

Speaking of arctic ice. Tamino has just done a new blog post: http://tamino.wordpress.com/2012/04/27/lets-do-the-math/ There is plot of the annual cycle amplitude, that just explode after 2005. Clearly arctic ice has change of dynamical regime. IMHO it would be wise to trough away any data before 2006.

Actually, the real value of Cryosat-2 will comes from the added data in the assimilation model like PIOMAS. PIOMAS does not have much measurement to constrain its physical model. Cryosat-2 will improve this aspect very much.

@Rob Dekker Your analysis is wrong. You can measure distance with a precision higher than the wavelength with enough SNR. Jason altimeter only work at 5.3 and 13.6 GHz but still manage to get mm precision. In addition, GPS transmit at 1.023 MHz, 1227.60 MHz and 1575.42 MHz but can still manage mm precision with enough integration.

Speeking of PIOMAS, there is this nice post about it on Realclimate: http://www.realclimate.org/index.php/archives/2012/04/arctic-sea-ice-volume-piomas-prediction-and-the-perils-of-extrapolation/#more-11432

A whole week of temperature above 0C is expected in Quebec. Normally, snow cover should not survived this week.

I not sure this post has been send last time. Ice is dispersing on Great Lakes too. http://earthsky.org/earth/north-americas-great-lakes-are-losing-ice

Even is limiter at 0.5 m, this is still a good step. More means better constrains on model, which will improve thickness estimation elsewhere in the pack.

Hot from the press: Arctic warming, increasing snow cover and widespread boreal winter cooling http://iopscience.iop.org/1748-9326/7/1/014007

I checked the data from Barrow. Many indicator are anomalous: CH4, CO2, H2, isotopic ratio. This looks suspicious for me. By the way, you need to check the last to year otherwise the anomalous data point get hidden behind the NOAA logo :)

The scariest story I have read recently: http://www.independent.co.uk/environment/climate-change/shock-as-retreat-of-arctic-sea-ice-releases-deadly-greenhouse-gas-6276134.html

Ozone is destroyed by chemical reaction ongoing on polar stratospheric cloud. They only form at very low temperature. When troposphere heats due to a reduction of the atmospheric transmittance (Say more CO2 and H2O) there is less heat going higher in the atmosphere. Off course, you can write your own radiation transfer code to be sure ;)

Paul, there is an easy way to check this out. All we have to do is calculate the cross-correlation between each data set. Time lag could be easily determined. My general impression, is that over a year,number will average out and the residual lag will be very small. If someone can point me to the right data source, I could do the analysis very rapidly.

Speaking of icebergs. There is this nice iceberg tracking website. http://www.icebergfinder.com/iceberg-map.aspx

While we watch the Arctic melting, Antarctic refuses to freeze: http://www.iup.uni-bremen.de:8084/amsr/ice_ext_s.png

@Bfraser I am amazed how poor is the understanding of the science from those guys. The beginning of the paper looked good then intellectual bias exploded in my face.