I’m really quite surprised to find this paper in Nature, especially when it makes claims so counter to the consensus that model projections are essentially a map of the future climate.
The Hockey Shtick writes: Settled Science: New paper ‘challenges consensus about what regulates atmospheric CO2 from year to year’.
A new paper published in Nature “challenges the current consensus about what regulates atmospheric CO2 from year to year” and finds “semi-arid ecosystems in the Southern Hemisphere may be largely responsible for changes in global concentrations of atmospheric CO2.”
The authors find links between the land CO2 sink in these semi-arid ecosystems “are currently missing from many major climate models.” In addition, they find that land sinks for CO2 are keeping up with the increase in CO2 emissions, thus modeled projections of exponential increases of CO2 in the future are likely exaggerated.
The paper joins many other papers published over the past 2 years overturning the “settled science” of the global carbon cycle.
Climate science: A sink down under
- Nature (2014) doi:10.1038/nature13341
- Published online21 May 2014
The finding that semi-arid ecosystems in the Southern Hemisphere may be largely responsible for changes in global concentrations of atmospheric carbon dioxide has repercussions for future levels of this greenhouse gas.
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature13341.html
more here: http://hockeyschtick.blogspot.com/
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richardscourtney says:
May 28, 2014 at 6:51 am
Richard, the reliability of ice core CO2 data was investigated already in 1996 by Etheridge e.a. on three Law Dome ice cores. Drilled by different techniques, CO2 sampled top down in firn and ice from the surface to rock bottom. That confirmed the “firn densification model” which calculates the composition of the air in the firn and ice for age distribution.
Thus while not samples of one year, they are averaged samples of 10-600 years of ancient air, still the same since the bubbles were closed, except for some theoretical migration in “warm” ice cores. As far as there is any CO2 migration in the ice, that only broadens the resolution, but doesn’t change the average over the resolution period.
Stomata data have a much better resolution but are proxies, based on the change in average CO2 levels at the location of growth in the previous growing season and some other factors. If there is a discrepancy between the averages of ice cores and stomata data, then it are the stomata data which local positive bias did change over the centuries, not the ice cores that are too low.
Thus while stomata show more variability and a better resolution, one should take the absolute values (and the amplitude of the variability) with a grain of salt.
About the cause of the recent increase: At least one can use the “human hypothesis” as a working hypothesis. As long as there is no contradiction with any of the observations, the hypothesis is valid. If there is a better hypothesis that still fits all observations, then the first can be abandoned…