Heck, I believe CO2 is a greenhouse gas and as such it warms the atmosphere. A little bit. I don't believe there are massive positive feedbacks that magnify CO2s direct greenhouse effect by 3 or 4 times like alarmists do. This is an assumption that underlies all the catastrophe promoting GCM's.
What we see from glacial evidence is that atmospheric CO2 rises FOLLOWING warming periods. Furthermore I know CO2 is a trace gas measured in parts per million (currently about 400 ppm). AND it's vital for life on earth.
I also know that trees from the last period of glacial advance preserved at the La Brea tar pits showed signs of CARBON STARVATION. IOW the atmospheric CO2 level then was so low that tree growth was stunted. If the geological processes that've been taking carbon out of the atmosphere and burying it underground as fossil fuels continued long enough, life on earth would end. Thank God the fossil fuel industries have put off that day and gotten CO2 back up to a healthy plant growth promoting level (about twice the starvation level of the last glacial period). Hopefully this process will continue for a long time. We need healthy plant life.
Title: Carbon starvation in glacial trees recovered from the La Brea tar pits, southern California
Author: Ward, Joy K.; Harris, John M.; Cerling, Thure E.; Wiedenhoeft, Alex; Lott, Michael J.; Dearing, Maria-Denise; Coltrain, Joan B.; Ehleringer, James R.
Or: http://www.fpl.fs.fed.us/documnts/pdf2005/fpl_2005_ward001.pdf
Date: 2005
Source: Proceedings of the National Academy of Sciences of the United States of America. Vol. 102, no. 3 (Jan. 18, 2005): p. 690-694.
Publication Series: Miscellaneous Publication
Description: The Rancho La Brea tar pit fossil collection includes Juniperus (C3) wood specimens that 14C date between 7.7 and 55 thousand years (kyr) B.P., providing a constrained record of plant response for southern California during the last glacial period. Atmospheric CO2 concentration ([CO2]) ranged between 180 and 220 ppm during glacial periods, rose to 280 ppm before the industrial period, and is currently approaching 380 ppm in the modern atmosphere. Here we report on [delta]13C of Juniperus wood cellulose, and show that glacial and modern trees were operating at similar leaf- intercellular [CO2](ci)/atmospheric [CO2](ca) values. As a result, glacial trees were operating at ci values much closer to the CO2-compensation point for C3 photosynthesis than modern trees, indicating that glacial trees were undergoing carbon starvation. In addition, we modeled relative humidity by using [delta]18O of cellulose from the same Juniperus specimens and found that glacial humidity was 10% higher than that in modern times, indicating that differences in vapor-pressure deficits did not impose additional constrictions on ci/ca in the past. By scaling ancient ci values to plant growth by using modern relationships, we found evidence that C3 primary productivity was greatly diminished in southern California during the last glacial period.
Keywords: Low CO2, paleoclimate, Juniperus, ci/ca, ancient wood, ancient NPP, radiocarbon dating, carbon isotopes, humidity, climatic changes, fossil trees, juniper, paleobotany, vapor pressure, carbon dioxide, tar pits, La Brea Pits (Calif.)
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Citation:
Ward, Joy K.; Harris, John M.; Cerling, Thure E.; Wiedenhoeft, Alex; Lott, Michael J.; Dearing, Maria-Denise; Coltrain, Joan B.; Ehleringer, James R. 2005. Carbon starvation in glacial trees recovered from the La Brea tar pits, southern California. Proceedings of the National Academy of Sciences of the United States of America. Vol. 102, no. 3 (Jan. 18, 2005): p. 690-694.
http://www.treesearch.fs.fed.us/pubs/22081 |
