Saturday, September 15, 2007

Arctic Ice Melting faster than Global Warming Models Predict.

During this summer of torrential rain in the UK, the Arctic ice has melted at a rate hitherto unknown, and the amounts of sea-ice in the Arctic ocean are at a record low, at least for the duration of accurate measurements of it, which began about 30 years ago. To lend a sense of scale to the process, it is reported that an area "almost twice as big as the UK" was lost in the past week alone.

Many lost their lives trying to navigate the putative course of the Northwest passage across the top of Canada, including the two-ship ("The Terror" and "The Erebus") expedition of Sir John Franklin in 1845. Traces of the expedition have been found, including notes that indicate that the ships became ice-locked in 1846 near King William island, about half way through the passage, and were unable to extricate themselves, with the loss of 129 lives. Franklin himself died in 1847 and the last of the party died in 1848. However, so much ice has been lost during this summer the passage is presently fully navigable, and observers believe that the Northeast passage along the Arctic coast of Russia could become so later this month.

The importance of the Northwest passage was to provide a sailing link between Europe and Asia, avoiding the necessity to sail around the horn of Africa. I muse slightly, that in an era of higher global temperatures but restricted fuel supplies, such a trade-route could come into its own to ferry manufactured goods from the Far East to Europe, and even to North America, if it becomes more efficient to bring cargo to the west coast via the passage rather to to the East coast across the Pacific Ocean, and then to transport goods across the continent. Perhaps both routes will be used, depending on the closeness to the coast of their final inland destination?

Will we use sailing ships once more too, depending on the power of the wind rather than fossil fuels, although the volume of cargo that could be so borne would be implicitly reduced, and to essentials only. It may be that inland transportation will become a greater problem than oceanic travel, in the absence of liquid fuels, meaning that the coastal regions will flourish, along the lines of the original port-cities like London and Liverpool, existing almost separate from an agrarian hinterland. But those "cities" will still need to be fed, and possibly beyond the capacity of local farms, perhaps imposing a restriction on their actual level of growth.

These thoughts aside, why is the Arctic ice retreating to fast? The Arctic has lost around one third of the ice it had when detailed satellite measurements began thirty years ago, and the rate of its depletion has accelerated abruptly since 2002. Dr Mark Serreze, at Colorado University (where the US National Snow and Ice Data Center is), said: "If you asked me a couple of years ago when the Arctic could lose all of its ice then I would have said 2100, or 2070 maybe. But now I think that 2030 is a reasonable estimate. It seems the Arctic is going to be a very different place within our lifetimes, and certainly within our children's lifetimes." It appears therefore, that climate models are not able to account for the phenomenon, and perhaps there is another factor involved which is not encoded into the various algorithms, whatever that might be.

The latest measurements show that the area of remaining sea-ice is 4.4 million square kilometres. The previous record low was 5.3 million km^2 in September 2005, as compared with an average of 7.7 million km^2 between 1979 and 2000. The sea-ice usually melts in the Arctic summer and freezes once more during the winter; however Dr Serreze thinks this year that will be difficult, noting that: "This summer we've got all this open water and added heat going into the ocean. That is going to make it much harder for the ice to grow back.

Changes in wind and ocean circulation patterns can help reduce the amount of sea-ice but Dr Serreze said the main culprit is man-made global warming, commenting: "The rules are starting to change and what's changing the rules is the input of greenhouse gases." So why don't the models predict what is happening, and might there not be an additional forcing factor, perhaps a flow of warmer water from somewhere, as might explain the unexpectedly rapid melting of the Larsen-B Shelf in Antarctica?

I leave these matters to the experts and their calculations, but await their results in a combination of concern and interest.

Related Reading.
(1) "Loss of Arctic ice leaves experts stunned," By David Adam, Guardian Unlimited:

No comments: