The Old Man was looking at recent conditions to try for a prediction of next year’s sea ice minimum. More on this shortly; during the research, what came up was the ENSO. It’s neutral at the moment, predicted to be for the next six months. But an eyeball of the Pacific SSTAs raised a question about the direction and strength of the ocean currents, and the direction and strength of SSTAs.
I don’t know if these two are directly linked, but I imagine they are. If this is correct, then it seems reasonable to predict, this far out, that we could be in for a very strong El Nino, starting late in 2009 and continuing for at least two years.
This is mainly based on an interpretation of the 2008 Sea surface temperature anomaly pattern in the Pacific and its relation to ocean current direction and the ENSO area. There is a moderately strong positive anomaly in the Southern part of the West Pacific, stretching along the line of the current in that part of the Ocean, and apparently heading towards South America. There is a huge positive anomaly in the North Western sector, which should be associated with the North Pacific current, which heads towards the US west coast.
On an eyeball analysis, the pattern of Pacific SSTA is a broad clockwise motion in the Nothern hemisphere, and a broad counter-clockwise motion in the Souther Hemisphere. Thus, currents move across the equatorial region from the Americas to Japan (yes, there’s also an equatorial counter-current), go round in a big loop to North and South, and come round the American coasts and back towards the Equatorial region, where ENSO is formed.
There’s vertical mixing to take into account, as well as the flow between the Atlantic and Pacific, but this latter I suspect is a longer-term relationship (which would still, nonetheless, likely exhibit a positive anomaly). There’s a very good chance that a half-competent oceanographer will be able to explain what I’ve overlooked, and that this projection/prediction is nonsense.
Given the trend in global surface temperatures, the current state of NH snow and ice cover, recent ENSO trends and the generally warm oceans, and since my reputation or career is not on the line, I am now going to say that we are probably heading for a monstrous El Nino, starting either late 2009 or early 2010. Why does this matter?
Back to the sea ice. The Old Man’s mind isn’t entirely made up about the forthcoming melt season, though early indicators are that this Winter will be mild in the NH and snow cover (hence albedo) will continue to be well below average. At the moment, the feeling is that there is a chance that 2009’s summer melt will exceed the record set in 2007, but the analysis is ongoing. In the longer term, though, if (big, big if) we get an El Nino in ’09, then 2010 will almost certainly beat 2007. If we have a strong continuing El Nino through 2009 and 2010, then there is a chance that the Arctic Ocean will be effectively ice free (except along the North Greenland coast) in the Summer of 2011.
Definitely want feedback from scientists on this one…
Edit: There’s a technical description of the recent trends in sea ice loss here: no mention of the El Nino, but the Search/ARCUS summary of 2008 suggests that the current condition will continue until a new warm season triggers another stage of decline.