Greetings from the flood zone. I am fine - thank you - but traumatised by the deaths and angered and saddened by idiots who seek to make a political point out of tragedy. Both sides of this argument are full of shit - intellectual featherweights who are instant internet experts on everything and are utterly convinced of their own logical infallibility. Both sides angling to blame the deaths and destruction on the other. I wish they would pull their f....... heads in.
Rant over - I thought I would see if I could put a ruler under 20 years of work. Neither the floods or the current La Nina are notably unusual over the longer term - it is part of a Pacific decadal pattern that is likely to lead to decades more intense and frequent La Nina. see - http://www.earthandocean.robertellison.com.au/index.html As an Australian hydrologist, I was introduced to the concept of drought dominated and flood dominated regimes (DDR and FDR) in the late 1980’s. These are 20 to 40 year periods dominated by droughts followed by a 20 to 40 year period dominated by floods. The original result was replicated dozens of times across Australia in the following decade. In 1997 the Pacific Decadal Oscillation was described defining a link between sea surface temperatures and fisheries biology. The periods of the PDO modes were exactly the same as the periods of DDR and FDR. An apparent but astonishingly odd link between North American fisheries and Australian rainfall. Over the following decade it emerged that the PDO is part of a pattern of decadal and longer changes in sea surface temperature in the Pacific Basin with teleconnections to Asian, Australian, African and American rainfall - and seemingly to the formation of cyclones in the Atlantic. In 2003 I made the mistake of looking closely at the Climatic Research Unit surface temperature record - and saw that the inflection points are at exactly the same periods as the transitions between DDR and FDR and between PDO modes. Still looking for the causes of DDR and FDR I read nearly everything that emerged on the PDO and the El Niño Southern Oscillation (ENSO). However, without much of an idea anywhere of causative mechanisms, there was not much more than an intriguing similarity in the timing of changes. More recent work has identified the Pacific Ocean climate system as chaotic. As I eventually realised, chaos is not just a word but a property of complex and dynamic systems in chaos theory. It explains abruptness in the changes observed in ocean states and therefore in global temperature and in the transitions of Australian rainfall regimes. It changes the way in which climate risk is viewed. Where before, climate evolved slowly with cycles of minor warming and cooling in a system that is far from driven solely by greenhouse gas forcing. After chaos theory, climate change is abrupt and predictable only as a probability density function. There is objectively a small risk of catastrophic climate change (warming or cooling) that could happen within months as a result of anthropogenic greenhouse gas emissions. Currently, revisions to existing satellite records, new data sources for radiative flux and ocean heat content, new theoretical work and computer modeling and new compilations of surface cloud observations are providing new ways of confirming a Pacific Ocean influence on global climate. The picture that emerges is of the Pacific Ocean as far and away the major driver of global climate. It does this primarily by changing cloud formation dynamics. More cloud forms above cold water - and the biggest change to sea surface temperature on interannual, decadal and millennial scales occurs as a result of upwelling of cold and nutrient rich (and also acidic) sub-surface water in the eastern Pacific. These changes in cloud cover are seen in surface observations of cloud over the Pacific, in satellite measurements of reflected shortwave and outgoing long wave radiation and in modeling studies. Most recent climate change has been as a result of changing cloud cover. And the cause of these changes? A small change in the initial conditions of a complex and dynamic system that most probably involves top down forcing by solar UV heating of ozone in the upper atmosphere. As Judith Lean says - ‘ongoing studies are beginning to decipher the empirical Sun-climate connections as a combination of responses to direct solar heating of the surface and lower atmosphere, and indirect heating via solar UV irradiance impacts on the ozone layer and middle atmospheric, with subsequent communication to the surface and climate. The associated physical pathways appear to involve the modulation of existing dynamical and circulation atmosphere-ocean couplings, including the ENSO and the Quasi-Biennial Oscillation.' Cheers Robert -- You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/globalchange
