On a new weather and climate site, Totally weather and climate, someone wrote the comment below to me:I am watching the rise in the arctic ice very carefully as I think it really does resememble watching the signals from a life support machine. If we see significantly higher ice levels this time next year a lot more people will be asking a lot more questions. Two years in a row and possible will have become probable. It woul dbe interesting to see all of the explanations.I live in hope.
To which I replied:
As a student of Arctic sea ice conditions, I’d advise caution over this approach. The interannual variability is huge and the signal-noise ratio small. There is only so much we can garner from any one or two seasons of watching.
As I said elsewhere, climate change needs thinking of on longer timescales to be meaningful.
Take 2008’s melt season, now apparently over; it was slightly less than record-breaking, but not by much. If there was a surprise in ice conditions this year, it was the rate of recovery over the Winter, followed by the relatively slow start to the melt season, which was probably unexpected.
Are we likely to see significantly higher ice levels (I presume here you mean the Summer minimum) next year? Given the state of the multi-year ice, I’d say no. But I’d also look at the ENSO predictions for the next six-twelve months, and try to factor this in, too. Then I’d want to look at the AO and factors such as the Bering and Fram inflow/outflow numbers, and the coming seasons’ NH snow cover (Albedo!), the general sea circulation, and areas of potential forcing such as the north Pacific, Labrador and the GIS ridge.
Taking these into account, then looking at the long term trend, a conservative estimate would be that 2009’s melt season is likely to be comparable to 2008’s, with a 25% chance of it becoming like 2007’s, or worse (though 07 and 08 were very similar, in the end).
If people see two consecutive years of summer minima close to the long term average, they might be inclined to speculate whether we really understand enough about the Arctic to use it as a benchmark for GW. Technically, they’d be wrong to do so, though it is easy to see why the temptation is there. Realistically, there is no reason, at the moment, to think that next year will be any better than any one of the last ten, ie, well below the long-term average. My predicion is that the minimum will be exceeded in the first Summer season following the next el-nino, if not before.
I’d be interested to know who agrees/disagrees with my ‘predictions’, and why; am I missing something?