Hi Folks, Regrettably, I can not read the full paper and can only offer up minor comments/questions which might be covered in the full paper. The abstract closes with: *"**Carbon dioxide is involved, but is not determinative, in the evolution of the 100,000-year glacial cycles.". *What is clearly different from our current situation and the past cycles is the rapid amplification of yearly CO2 respiration and CO2 build up. In simple terms, the earth is taking much deeper annual breaths involving volumes of CO2 not seen throughout the studies' time frame.
Here is a paper showing the respiratory increase for just the last 50 yrs.: "*Enhanced Seasonal Exchange of CO2 by Northern Ecosystems Since 1960"*<http://www.sciencemag.org/content/early/2013/08/07/science.1239207.abstract?sid=2301f98c-d1de-4562-86f8-ea1a020b5103> *"Seasonal variations of atmospheric carbon dioxide (CO2) in the Northern Hemisphere have increased since the 1950s, but sparse observations have prevented a clear assessment of the patterns of long-term change and the underlying mechanisms. We compare recent aircraft-based observations of CO2 above the North Pacific and Arctic Oceans to earlier data from 1958 to 1961 and find that the seasonal amplitude at altitudes of 3 to 6 km increased by 50% for 45° to 90°N but by less than 25% for 10° to 45°N. An approximately 50% increase in seasonal exchange of CO2 by northern extratropical land ecosystems, focused on boreal forests, is implicated, substantially more than simulated by current land ecosystem models. The observations appear to signal large ecological changes in northern forests and a major shift in the global carbon cycle."* * * My question is: Can this unprecedented annual fluctuation and volume of CO2 act as a tipping point capable of "trigger(ing) a negative (ice) mass balance" in the Arctic? In simple terms, can the current planetary respiration system 'volume' spike to the extent that a rapid decrease in Arctic ice happens regardless of planetary average temperatures? Or, Abe-Ouchi<http://www.nature.com/nature/journal/v500/n7461/full/nature12374.html?WT.ec_id=NATURE-20130808#auth-1> et al. states: *"**the shape and position of the hysteresis loop playing a key part in determining the periodicities of glacial cycles"*. Can our current CO2 respiration depth change the "shape" of the hysteresis loop? Thanks for yet another interesting puzzle. Best, Michael On Thursday, August 8, 2013 9:11:11 AM UTC-7, Stephen Salter wrote: > > Hi All > > The site > > > http://www.nature.com/nature/journal/v500/n7461/full/nature12374.html?WT.ec_id=NATURE-20130808 > > > has an interesting paper about cycles of ices ages. There are different > equilibrium states. > > Stephen > -- > Emeritus Professor of Engineering Design School of Engineering > University of Edinburgh Mayfield Road Edinburgh EH9 3JL Scotland > s.sa...@ed.ac.uk <javascript:> Tel +44 (0)131 650 5704 Cell 07795 203 195 > WWW.see.ed.ac.uk/~shs > > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/groups/opt_out.
