As one of the “stomata” people and author of the cited Tellus paper, I want to draw attention to one of the most interesting outcomes of our research. That is that for the past thousand years the stomata records seem to match with respect to timing to two Antarctic ice core records which are not often cited…. Matching variabilities between ice cores of such resolution has not been achieved yet… well, ice core people claim that they reproduce their flat liners, but if you zoom into detail the small fluxes never match with respect to timing… The lone fact that stomata data of the USA and Europe have the same timing of a CO2 wiggle which has also been recorded (but with a much lower amplitude) in two Antarctic ice cores is evidence enough that Co2 variability has been larger in the past millennium then assumed. If the variability would have been as small as the ice cores tell us, plants would never ever have picked up this signal on two different continents on another hemisphere…
[F]or the somewhat older stomata data ( I focussed on the past 1000 yrs but my colleages on the whole Holocene) there are Greenland iced-core records which match pretty well… However, we can’t use them for publictions as the ice community officially redrew them as soon as the Antarctic records became available.. they claimed the records are contaminated by too much dust in the ice….
Furthermore I want to mention that we fully understand there are uncertainties with the stomata data. what bothers me is that for our records the scientific community focusses on these uncertainties in exact prediction while all the flaws and errors in ice data are ignored… furthermore it is quite amusing for me as a biologist to read the papers where physicists try to attack the proxies by playing plant physiologist…. I am very surprised the scientific community does not have a very warm welcome for new innovative techniques when those techniques put question marks at established ideas.., I always learned that these discussions are the fundamental backbone for science… therefore my hope that climate science will ever become a fullgrown scientific discipline is lost as long as politics (read funding) keeps intermingling..
Dr van Hoof is referring to Dave Middleton’s analysis here:
The “cited Tellus paper” is:
Van Hoof et al., 2005. Atmospheric CO2 during the 13th century AD: reconciliation of data from ice core measurements and stomatal frequency analysis. Tellus (2005), 57B, 351–355.