Even though increased burning of fossil fuels puts more carbon dioxide into the atmosphere, new research from Australia suggests that natural temperature variation is principally responsible for the rise in atmospheric carbon dioxide concentration. This research is reported on in a long blog from JoNova, an Australian science writer. “The climate models assume that most of the rise in CO2, from 280 ppmv in1780 to 392 ppmv today, was due to industrialization and fossil fuel use. But the globe has been warming during that period (in fact since the depths of the Little Ice Age around 1680), so warmer conditions could be the reason that CO2 has been rising.”
The research is based upon the ratio of two isotopes of carbon, the very abundant C12 and the rare C13. Satellite measurements of ambient atmospheric carbon dioxide find concentrations, not in the industrialized northern hemisphere where we would expect it to be high, but rather in places like the Amazon Basin, southeast Asia, and tropical Africa.
The question arises of how fast emissions from the industrialized north mix in the global atmosphere. “A tracer for CO2 transport from the Northern Hemisphere to the Southern Hemisphere was provided by 14C created by nuclear weapons testing in the 1950’s and 1960’s. The analysis of 14C in atmospheric CO2 showed that it took some years for exchanges of CO2 between the hemispheres before the 14C was uniformly distributed.”
However, there appears to be no significant time lag in correlation of temperature variations with carbon dioxide concentration.
The first graph below, from the JoNova blog, shows human carbon dioxide emissions (top line) versus measured carbon dioxide concentration changes in the atmosphere. Below that I include the satellite temperature record from the University of Alabama, Huntsville. Notice that the variations in atmospheric carbon dioxide concentrations correlate well with temperature, but do not correlate with human emissions.
Conclusion from the research:
“…man-made emissions have only a small effect on global CO2 levels.”
The research will shortly be published in a peer-reviewed journal. For a more detailed explanation of the research go to the JoNova blog here.