A new paper was published in Nature on 13th September, with Jan Veizer as a co-author, entitled ‘Coupling of surface temperatures and atmospheric CO2 concentrations during the Palaeozoic era.’
The abstract says:
Atmospheric carbon dioxide concentrations seem to have been several times modern levels during much of the Palaeozoic era (543–248 million years ago), but decreased during the Carboniferous period to concentrations similar to that of today. Given that carbon dioxide is a greenhouse gas, it has been proposed that surface temperatures were significantly higher during the earlier portions of the Palaeozoic era. A reconstruction of tropical sea surface temperatures based on the 18O of carbonate fossils indicates, however, that the magnitude of temperature variability throughout this period was small4, suggesting that global climate may be independent of variations in atmospheric carbon dioxide concentration. Here we present estimates of sea surface temperatures that were obtained from fossil brachiopod and mollusc shells using the ‘carbonate clumped isotope’ method—an approach that, unlike the 18O method, does not require independent estimates of the isotopic composition of the Palaeozoic ocean. Our results indicate that tropical sea surface temperatures were significantly higher than today during the Early Silurian period (443–423 Myr ago), when carbon dioxide concentrations are thought to have been relatively high, and were broadly similar to today during the Late Carboniferous period (314–300 Myr ago), when carbon dioxide concentrations are thought to have been similar to the present-day value. Our results are consistent with the proposal that increased atmospheric carbon dioxide concentrations drive or amplify increased global temperatures.
Steve Milloy of junkscience.com has spoken to Veizer:
A new study published in the journal Nature (Sep. 13) crafted to support the notion that increases in atmospheric carbon dioxide drive increases in global temperature actually, if read carefully, casts further doubt on that idea.
The story begins in 2000 when the University of Ottawa’s Jan Veizer and others published a study in Nature reporting that their reconstruction (via fossil shells) of tropical sea surface temperatures for that last 550 million years only made sense if carbon dioxide were not the principle driver of climate variability on a geological timescale.
Veizer, along with Nir Shaviv of the Hebrew University of Jerusalem, followed up the 2000 paper with a July 2003 study in GSA Today (a journal published by the Geological Society of America). That report said at least 66 percent and perhaps as much as 75 percent of the variance in the Earth’s temperature over the past 500 million years may be due to cosmic ray flux.
Obviously, none of this was good for ever-fragile climate hysteria and the alarmists struck back with the new Nature study, which, surprisingly, includes Veizer as a co-author.
The new study that uses a different method to reconstruct sea surface temperatures from fossil shells claims to report results that “are consistent with the proposal that increased atmospheric carbon dioxide concentrations drive or amplify increased global temperatures.”
So has Veizer participated in the debunking of his own work as the new study seems to imply? Hardly.
First, Veizer reluctantly told me the “text” of the Nature study, that is, the above-quoted conclusion, represented a “compromise” between the study’s disagreeing authors where Veizer’s side apparently did all the compromising for reasons that had little to do with the science.
While Veizer didn’t want to elaborate on the politics of the Nature study, he told me “not to take the tone of the paper as the definitive last word.”
Veizer went on to say that the new Nature study has not refuted his original study. The new study, in fact, appears to have confirmed the original study with respect to its most important point that the historical sea surface temperature data indicate atmospheric carbon dioxide does not drive global temperature.
Even if the new study proves to be valid, Veizer says, at most it reduces the statistical variation in sea surface temperature estimated by the original study. This correction, however, has little bearing on the nature of the carbon dioxide-temperature relationship.
Veizer says the basic pattern of reconstructed sea surface temperatures in both his original study and the new study remain inconsistent with notion that atmospheric carbon dioxide drives global temperatures.
If it turns out that the new study reconstructs historical sea surface temperatures more accurately than his original study, Veizer added, it would only represent an increase in the impact of cosmic rays on the climate that was reported in the 2003 GSA Today paper.
There’s another point worth spotlighting in all this. It seems that the politics of global warming including the multibillion-dollar-funding of global warming research resulted in the publication in a prestigious science journal of a “compromise” conclusion that is not supported by the study’s own data.