So ok, in the middle of one of the better tornados: weather or climate change? scrums Eli threw a curveball to John N-G, innocently asking
FWIW do the floods in Australia have anything to do with what people are doing to the atmosphere?and got back a disputation
Now, if Eli has taught the bunnies anything, it is to look at awkwardly put questions with a jaundiced eye. The sort of thing that Damon Runyon put best in a father's advice to a son going out into the world
[Eli- The contemporaneous Reuters story http://www.reuters.com/article/2011/01/12/climate-australia-floods-idUSL3E7CC0KG20110112 does a decent job of summarizing the situation. (I say "decent" because I agree with it.) La Nina set up the weather pattern (there's no clear relationship between La Ninas and AGW), but the exceptionally warm oceanic temperatures in the area provided an extra dose of water vapor to the atmosphere, providing an add-on of 5%-7% to the flood-causing rainfall.
In a month or so I'll be in Melbourne attending an international earth science conference and I'll be keeping an eye (or ear) out for indigenous presentations on this topic.
We'll have an official answer in a year or so whether land use and urban planning contributed to the flood's impact to a significant extent. http://www.urbanalyst.com/in-the-news/401/401.html - John N-G]
Son, my father told me, there will come a time when you are out in the world and you will meet a man who says he can make a jack of hearts spit cider into your ear. Son, even if this man has a brand-new deck of cards wrapped in cellophane, do not bet that man, because if you do, you will have a mighty wet ear.Observant bunnies note the use of the words "what people are doing to the atmosphere" and the answer (coming up) is a nice example for the next time Watts and Co. have a fit about using the term climate change instead of global warming, for indeed, we are doing more than simply taking a blow torch to the atmosphere, and, in broad outline, what we are doing can be understood in simple ways, although complex models provide needed detail.
Goes like this, springtime ozone depletion over Antarctica blows a hole in the belly of the ozone column. That means that there is a lot less ozone over the pole in the stratosphere. Eli has been at this game long enough to have heard every possible joke about sunburned penguins and more serious thoughts about this not doing good things for the phytoplankton upon which much of the oceans food chains depend, but it does something else that is obvious, it causes a strong, local (over the pole) cooling of the stratosphere, because the ozone is not there to absorb the sunlight which is flooding in as the sun rises in the spring. Such a cooling moves the tropopause upwards. Let us stress that this is both a local effect and and a short term one until the ozone hole heals in the late spring/summer.
Lagomorphs, and even pica everywhere ask, what does this have to do with weather (yes, yes, Eli knows) it rains in Brisbane, let alone Spain. To answer this question come Kang, Polvani, Fyfe and Sigmond in Science 332 (2011) 951 and to be honest a bunch of other people before them referenced in the "Impact of Polar Ozone Depletion on Subtropical Precipitation. They point out that there has been a strong movement of the Southern Hemisphere westerly jet towards the pole driven by the lifting of the tropopause associated with the Antarctic ozone depletion.
Kang and friends argue, supported by modeling that this effect is seen even as far as the tropics as the Hadley cells shift poleward, an observed trend.
Observations, cooling of the stratosphere due to the formation of the ozone hole, increased precipitation between 20 and 40 S latitude, shifting of the Southern Hemisphere westerly jet and the Hadley cell, poleward, and, oh yes, flooding in Australia can all be drawn together qualitatively as shown in the picture to the left taken from Feldstein's appreciation in the same volume of Science, and quantitatively with GCMs.