Saturday 24 October 2015

The Winds of Change

Just four weeks ago, I went all Armageddon on you by flagging a temperature anomaly in the North Atlantic.  The naive physics of it is that a or ml of water weighs, by definition, 1g; whereas a of air weighs 1.2mg.  Water has about 800x the mass per equivalent volume. Increasing the temperature of 1 lt of water by 1oC will bring up the temperature of 800 lt of air as things equilibrate.  That's what causes the winds: as this warmed air surges upwards and is replaced by cooler air from the surface surroundings.  Not quite a Dresden fire-storm but the principle is the same. I suggested that the pool of cold water in the Atlantic may shift the Gulf Stream further South and make for a cold dry winter here in Ireland. On the other side of the World, The Blob has been warming the air above and shifting the weather in quite unpredictable ways.

Nearer the tropics in the Pacific, El Niño is shaping up to be the second most massive example of this cyclical weather pattern since records began.  Previous biggies have been 1982-83 and 1997-98 and last night the meteorologists were telling us that El Niño had spawned the heftiest wet wind-storm ever recorded with sustained winds over 320 km/h and gusting even rougher. This would make it a category 7 hurricane if the scale didn't stop at category 5 = anything above 250km/h. To put that into parochial perspective, the Darwinday Storm of February 2014, had highest recorded winds of about 160km/h and that's the gusts not the sustained blowing. We're still clearing up the consequences. Hurricane Patricia, as they have called this monster is going to make landfall against the West Coast of Mexico this weekend with unbelievable storm-surges to flush everything that falls out to sea. 250km/h will take your car over a roadside hedge.  It is certainly comparable to Typhoon Haiyan that ripped through the Phillipines in 2013: Tacloban experienced 5m high storm surges at that time, which looked frighteningly like a tsunami. The best guess is that the force of Patricia will be broken by the mountains of the Sierra Madre Occidental but carry on into Texas where it will deliver up to 200mm of rain - 2 months supply - in a few hours. Sometime later it will be hosing down over our friends in New England and the Canadian Maritimes. STOP PRESS: the force of the storm is dissipating rapidly as it hits the coast between Puerta Vallarta and Manzanillo.  The people who abandonned their vacations at P.V. may have over-reacted.

In the medium term, they are also predicting a wet winter in California, which might sound like a good thing after a four year sustained drought has withered the fruit on the orchard trees. Nobody wants the rain all at once, though!  Furthermore, there is historical precedent for mega El Niños to swap out for a compensatory La Niña - the drying antidote to to the excesses of El Niño. There is a cunning plan afoot to re-introduce beavers Castor canadensis to the wilder upland parts of California to slow down the travel of water and retain it in slower, ponded rivers and streams. The clean fresh water of rain is getting to be an ever more precious commodity.  We don't have a great record for conserving it and trickling it out; beavers couldn't do a worse job!

What it looks like to Millennial Me is not so much that we have global warming but that we are due for much greater extremes of weather as the homeostasis of the last several thousand years breaks apart. I'm telling you this now, friends, so you can get to the shops before your neighbors. First World list including Spam, pepper-shaker and non-dairy creamer.  Costco's $800 Armageddon Food Package is more about shelf-life: "Freeze-dried foods have a shelf life of up to 25 years.  And the list of essential hardware is long.

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