Few weeks old... http://sj.farmonline.com.au/news/nationalrural/agribusiness-and-general/general/sunspot-drought-to-test-global-warming-theory/1625039.aspx?storypage=0
Sunspot drought to test global warming theory MATT CAWOOD 17/09/2009 1:32:00 PM EARTH is experiencing a sunspot drought which, if it persists, may deliver a make-or-break test of the theory of anthropogenic global warming (AGW). Along with a dearth of sunspots, NASA reports other signs of a current lull in the sun’s activity, including a 50-year low in solar wind pressure and a 12 year low in the sun’s brightness. Some scientists believe that these signs point to more than just a low point in the 11-year solar cycle. The sun may be entering a “deep solar minimum”. Previous solar minimums—the Maunder Minimum of 1645-1715, the Sp orer Minimum of 1460-1550 and the Dalton Minimum of 1790-1830—coincided with periods when Earth’s climate was colder than average. While the link between solar minimums and a dip in global temperature isn’t fully established, some believe that a solar minimum over the next couple of decades may be an acid test of whether greenhouse gas emissions are the primary cause of Earth’s sudden warming. Among them is University of New England researcher Dr Robert Baker, who has for several years been working on a theory that the sun is a key driver of Australian rainfall. The Dalton minimum occurred around the turn of the 18th century, and another minimum was recorded around the turn of the 19th century. If this roughly 100-year pattern repeats, Dr Baker believes we may be in for another multi-decade minimum with correspondingly lower global temperatures. “If we have a solar minimum and global temperatures continue to climb over the next decade, it will have established carbon dioxide as a potent force on the Earth’s climate,” Dr Baker said. “It’s going to be a very good scientific test of carbon’s real effect.” Dr Baker says the sun’s influence on global climate is underestimated. He has for several years been tracking 11-year solar cycles against the Southern Oscillation Index, with remarkable accuracy—until this year, when the relationship suddenly fell apart. Dr Baker believes this may be because the solar minimum has overridden the smaller cycles he’s been tracking. He is now working on a paper outlining a theory that the sun’s cycles influence rain-bearing cloud over the Pacific Ocean. How much cosmic radiation enters the Earth’s atmosphere, and how far it penetrates, in Dr Baker’s view largely depends on the polarity of the sun and Earth’s magnetic fields. His idea is that when the Earth’s magnetic field has been neutralised by negatively-charged particles from the sun, certain forms of cosmic radiation enter the atmosphere and encourage plankton development in the oceans. Plankton give off dimethyl sulphide, which is regarded as a potent agent of cloud nucleation—that is, water molecules cluster around the compound to the point that rain droplets are formed. Other forms of radiation in other cycles kill off plankton, Dr Baker believes, inhibiting cloud formation. Dr Baker says he has found a relationship between these processes and the El Nino-La Nina cycles. In its review of Sun-Earth interactions, the Intergovernmental Panel on Climate Change (IPCC) acknowledged that the sun influences Earth's climate patterns, but determined that human influences are now overriding those from the Sun. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
