Ice Loss from Greenland Spreading to Northwest Coast

As a local anecdote, Our ice roads have shut down 6 weeks early, and if the weather doesn't cool in the next week or two, we will be on track for not only the earliest ice out in history, but by a month!

We are already off the ice except in the very early morning, and then only very carefully. Record low lake levels, no snow to add run off, and very dry bush conditions,,,. I would call this weather,, except that in two of the last ten years we have had two of the earliest ice out dates ever. Our normal ice out is May 10th. The earliest ever is April 19th,, 2005,,2006. The latest ever was May 19th, 1969. I am predicting to be ice free by April 1.

 

Richard, this is a new paper in Geophysical Research Letters. It is the hardest journal to deal with (their server is often overwhelmed) but I can snag a copy if you need it.

Icarus, (you're not quite in Canada but) various news media have reported that Environment Canada says that the 09/10 Canadian winter was unusually warm in general. However I found no official statement to that effect at

Environment Canada - Media

 

Actually, we are in Canada, in far NW Ontario, half way between Lake Superior and Hudson's bay. While we are not that far north by geography, we are in a Sub Arctic climate zone. (Last night was -22) but it is supposed to be +10 by mid week) (-7f- 50f)

So, we see first hand the effect of warmer winters in a big way. The ice roads all over the north have been shut down over a month early this year, causing considerable hardship to some northern communities.

 

The IPCC's sea level projections always have this caveat: " ... excluding future rapid dynamical changes in ice flow." Nobody can model what will happen if the ice sheets start to flow rapidly. For that matter, I don't think anyone has any historical data (from the era of modern instrumentation) even to base a guess on. It's uncharted territory. So the IPCC has never included that in their projections. In effect, they assume the ice will more-or-less stay in place and melt.

But as I read this and similar stories, these "dynamic thinning" processes are at the point where they now account for the majority of ice loss.

This is something that James Hansen has stressed. Here's the argument.

If you look at the paleo data, the conclusion is that sooner or later, some generation is going to be faced with rapid sea level rise. The paleo data show pretty clear eras of rapid ice sheet collapse/sea level rise. They were rare eras, but they occurred. It happened before, its likely to happen again.

So it's not a question of whether this will occur, it's more a question of when. All you can do is hope it's far in the future. Hansen argues that the rapidity of the current warming, relative to historical rates of change, means we're more likely to see that sooner rather than later in this period of warming. Or, at least, that we should not ignore the possibility.

The IPCC-type projections of average sea level rise on the order of a foot or two in a century slur over the small probability that, sometime in the future, some generation will face eras when it rises ten times that fast. The dislocations and losses from very rapid rise will be much higher than from slow steady rise.

Therefore, projections of the cost of dealing with sea level rise are understated. They are based on IPCC-style median+/-uncertainty, depicting a slow steady rise. They ignore the (near) certainty that the slow, steady rise will be punctuated with periods of very rapid rise -- but we don't know when.

Hansen's point is that rapid rise will occur. You can only ignore it by assuming it'll occur in the far future. And that assumption may not be valid.