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Slightly slower than usual, here’s the NSIDC release for two days ago. In a couple of weeks, they’ll be producing their summary of September, and probably drawing the page to a close for the year not long after that. Before the monthly means are posted, though, these are the numbers we have so far for this year.

At it’s lowest, sea ice extent reached around 4.13 Mkm2, during the week of the 16th September; not especially late (the previous week has been the average over recent years), and earlier than some years. What is unusual about this month is the ‘flat-line’ appearance of the ice extent; normally, the refreeze starts as soon as the thaw has ended, and we get the familiar curved graph of extent; this month, the ice has persistently refused to start increasing in extent, in spite of the steadily decreasing temperatures. As a result, the September monthly mean is likely to come in around 4.2 Mkm2. How does this compare to previous years?

The Long-term mean Summer sea ice extent is 7.7 Mkm2. So, this month will have been around 3.5 Mkm2 lower than that mean; around 45% less. The previous lowest ever was two Septembers ago: 5.32 Mkm2. We’re around 1.1 Mkm2 lower than that; about 21% down.

In the meantime, ice extent in the Antarctic has pushed close to record high anomalies;  more than 1 Mkm2+ at its’ height. I haven’t yet seen any analysis of the data from here, or any novel explanations, but it still doesn’t look like the Antarctic  is  trending positively in a consistent way much beyond it’s natural variability; I’ll look for more on this later.

Ignoring the plight of Polar bears and local inhabitants for the moment, does the change in sea-ice matter? It does seem to be prima facie evidence of the ‘Polar Amplification’ hypothesis – not just this year’s low, but the trend over nearly thirty years, and the apparent (this year and 2005 could still turn out to be exceptional, rather than habitual) acceleration of the rate of decline in the NH.

But this year, at first glance, it at least looks as if the conditions in the Arctic are, somehow, different to previous years, not least because of the loss of a chunk of perennial sea ice in the Central Arctic Ocean, and the exceptionally low quantity of multi-year ice in the ocean as a whole, as well as the apparent inertia in the system this month.

What I am confused about, though, is how the huge amount of heat-loss from the ocean compared to previous years will effect the area next year. One the one hand, we may well see a slow and deficient refreeze throughout the Autumn and Winter, with a very large extent of vulnerable first-year ice. On the other, a vast amount of the heat transported in to Arctic Ocean via the NwAC and the Bering Strait will probably be removed from the climate system into the stratospher over the coming months. This is likely to have an impact on this Winter’s weather in Siberia and Northern Canada/Alaska, and more so in the Chukchi Sea area than anywhere else. There is also the possibility that the internal downwelling and upwelling circulation, as well as the boundary layer heights, will be affected.

It is far too soon to be claiming a systemic change in the Arctic yet, but the next four seasons may be critical in helping us understand what is and isn’t happening, and how the global climate system might respond.

Condoleeza Rice, speaking this evening, as reported by the BBC. Here’s an extract:

US Secretary of State Condoleezza Rice has said climate change is a real problem, and world leaders should forge a new global consensus on tackling it. At a meeting of the top 16 polluting countries, Ms Rice said the US was “a major emitter” and was not “above the international community on the issue”.

She said that the “growing problem” should be resolved under UN auspices.

Critics voiced concern that the US was trying to rally support for voluntary rather than binding emission cuts.

This would dilute attempts to reach a global agreement through the UN, ahead of the expiry of the Kyoto Protocol in 2012.

All nations should tackle climate change in the ways that they deem best

Condoleezza Rice

Motives behind Bush’s summit

US President George W Bush, who rejected the Kyoto Protocol in 2001, has opposed mandatory cuts, calling instead for voluntary approaches – echoed by China and India.

At the talks in Washington, Ms Rice said: “Though united by common goals and collective responsibility, all nations should tackle climate change in the ways they deem best.”

She challenged leaders to reduce their dependence on fossil fuels by moving toward energy sources that would reduce global warming – but without harming their economies.

Well, it could be argued that at least the Bush Government is starting to ‘talk the talk’, but nobody expects anything from his speech tomorrow, other than a call for a voluntary, non-binding, agreement. Wouldn’t it be great if China turned round and said ‘not good enough…’?

One question would be the apparent contradiction for any signatories between operating ‘under UN auspices’ and ‘in the way they deem best’. Does this mean that the UN should be seen as the authority on the matter, or does it mean that no matter what, the US will not be bound by the UN to an agreement? Take a guess.

As yet, there is still no indication that the Bush administration is willing to see beyond the short-term interests of its own people, and to see those interests in primarily economic terms. One question I would ask of Whitehouse watchers, though, is, if Bush’s people felt that the house might push through a bill which proposed real emissions cuts, would they feel compelled to pre-empt it by forcing through a much weaker bill in advance, to force it out into the cold?

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