Edgar, What mechanism do they propose for such an abrupt transition from extreme warming to cooling?
I would suggest a stoppage of the Gulf stream as a possibility based on plate movement. But I favor the change in albedo due to an unstable jet stream known to result from arctic warming. Richard On Sat, Mar 22, 2014 at 8:03 AM, Edgar L. Owen <[email protected]> wrote: > Richard, > > Yes, I noted that in the article. Another explanation I've read for the > current (geologically during the past million or so years) fairly regular > cycle of ice ages is that it is due to the current distribution of > continents, in particular the closing of the Isthmus of Panama which cut > off the Pacific Atlantic ocean interchange, and the isolation of Antarctica > at the S. pole which allows a free circulation of cold water around it > there. Apparently some climate scientistic think these two coincidences of > plate tectonics have allowed the current ice age cycles to develop due to > their fairly obvious control of global oceanic currents. > > Edgar > > > On Saturday, March 22, 2014 7:56:18 AM UTC-4, yanniru wrote: >> >> Edgar, >> The problem with the airborne iron explanation is that the decrease in >> atm CO2 must precede or be at least concurrent with the drop in global >> temp. The data indicates that CO2 follows temp but with a lag of 1000 years >> more or less. Besides all that, the iron explanation could not explain such >> abrupt transitions from extreme global warming to global cooling. It seems >> that the climatologists may recognize that the Milankovitch cycles are not >> a good explanation after all. >> Richard >> >> >> On Sat, Mar 22, 2014 at 7:40 AM, Edgar L. Owen <[email protected]> wrote: >> >> Richard, >> >> Here's is new research into one possible contributor to ice ages. Edgar >> >> Airborne Iron May Have Helped Cause Past Ice Ages >> 20 March 2014 2:00 pm >> [image: Life from dust. Iron-rich dust streaming from Patagonian deserts >> (red plume at left side of image) fertilizes nutrient-poor southern oceans, >> thereby pulling planet-warming carbon dioxide from the >> atmosphere.]*NASA/Goddard >> Space Flight Center, William M. Putman and Arlindo M. da Silva* >> >> *Life from dust.* Iron-rich dust streaming from Patagonian deserts (red >> plume at left side of image) fertilizes nutrient-poor southern oceans, >> thereby pulling planet-warming carbon dioxide from the atmosphere. >> >> It seems straightforward: Iron-rich dust floating on the wind falls into >> the sea, where it nourishes organisms that suck carbon dioxide from the >> air. Over time, so much of this greenhouse gas disappears from the >> atmosphere that the planet begins to cool. Scientists have proposed that >> such a process contributed to past ice ages, but they haven't had strong >> evidence--until now. >> >> "This is a really good paper, a big step forward in the field," says >> Edward Boyle, a marine geochemist at the Massachusetts Institute of >> Technology in Cambridge. The research doesn't directly measure the amount >> of dissolved iron in the waters due to dust in previous eras, Boyle says, >> but "they provide a much better case for what [nitrogen levels] have done >> in the past"--information that can reveal the ebb and flow of ancient life. >> >> The notion that iron-rich dust could boost the growth of microorganisms >> that pull carbon dioxide from the air took hold in the late 1980s. During >> ice ages, when sea levels are low and broad areas of now-submerged coastal >> shallows are exposed, sediments rich in iron and other nutrients would dry >> out, the thinking went. Then, strong winds would loft that fine-grained, >> dehydrated dust and carry it far offshore, where it would nourish carbon >> dioxide-sucking phytoplankton at the base of the ocean's food chain. >> Previous analyses of sediments that accumulated on sea floors during past >> millennia suggest that increases in iron-rich dust falling into surface >> waters boost biological productivity there, but those studies provide only >> a correlation in timing, says Alfredo Martínez-García, a paleoclimatologist >> at ETH Zurich in Switzerland. >> >> Now, Martínez-García and his colleagues have developed a new way >> >> ... > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
