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- Jun 9, 2011
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- Hillbilly Hollywood, Tenn
Just putting this up as a bookmark.. New study identifying correlation of solar activity with the glacial (ice age) oscillations.. More sturdy than the bad match to Milankovitch cycles to explain how the Earth went thru MULTIPLE Ice Ages --- one right after another for nearly a million years...
THE HOCKEY SCHTICK: Paper finds solar activity explains climate change over past 200,000 years
Paper finds solar activity explains climate change over past 200,000 years
A paper published in Earth and Planetary Science Letters finds solar activity was strongly correlated to climate change over the past 200,000 years. The paper reconstructs solar geomagnetic field strength using the 10Be isotope proxy of cosmic rays, which is inversely related to solar activity. The reconstruction in Figure 2 shows solar activity at the end of the record ["near present day"] was at some of the highest levels of the past 200,000 years, and solar geomagnetic field intensity approximately 3 times higher than during the ice age ~180,000 years ago.
Figure 4 below shows the strong correlation between solar activity [grey and black] and the climate change proxy [d18O in red] over the past 200,000 years. According to the author, "The marine δ18O [temperature proxy] record and solar modulation are strongly correlated at the 100,000 year timescale. It is proposed that variations in solar activity control the 100,000 year glacialinterglacial cycles."
Thus, the paper appears to solve the mystery of what causes ice ages and glacial-interglacial cycles, which has remained unsolved due to the so-called 100,000 year problem of using Milankovitch Cycles to explain ice ages. That is, ice ages and glacial-interglacial cycles are primarily caused by changes in solar activity rather than solar insolation changes on the Northern and Southern Hemispheres as described by Milankovitch Cycles.
According to the author,
"the geomagnetic field intensity appears to have varied by a factor of three over the last 200,000 years, with three excursions when the intensity became less than half the present value."
"there are strong correlations between solar surface magnetic activity and climate at different timescales, which range from days through centuries. Whereas these observations have pointed to a causal relationship between solar activity and climate change, the details of of physical mechanism(s) still need to be worked out. It has been generally believed that the variations in solar magnetic activity lead to changes in total or ultraviolet irradiance of the Sun through the disc passage and evolution of sunspots and faculae, which, in turn, affects climate. Another posited mechanism through which solar activity could directly affect climate is via modulation of GCRs [Galactic Cosmic Rays], which induces cloud formation by inducing changes in the tropospheric ion production [Svensmark's theory]. If the changes in cosmic ray flux cause cloud cover variations, one would expect an inverse relationship between solar modulation and surface temperature, assuming that the proportion of low and high clouds remains constant. This is consistent with the observations in Figure 4 [below], although variations in irradiance could also affect climate by e.g. affecting ozone cover."
"In summary, it is evident that while there are strong correlations between solar activity and climate at different timescales, more work is needed towards finding mechanisms that change solar activity in the first place, and that explain the physical link between solar magnetism and climate." "The long term solar activity and the Earth's surface temperature appear to be directly related. The variations in solar activity may control the 100,000 year glacial-interglacial cycles providing a more tangible astronomical forcing than the estimated changes in solar insolation [Milankovitch Cycles] or cosmic dust accretion rates."