Volume 7, Number 11: 17 March 2004
In our Editorial of 10 March 2004, we analyzed the "songs" of several canaries in the coal mines of high northern and southern latitudes, finding they provided not the slightest hint of CO2-induced warming in the regions of the world where the outlandish increase in temperature predicted by state-of-the-art climate models is supposed to be most strongly expressed and, therefore, most readily detected. Failing in our first attempt to find any signs of the elusive phenomenon, we here continue our search for it, analyzing another set of Arctic temperature data.
In this week's endeavor, we concentrate wholly on directly-measured temperatures, as opposed to the reconstructed temperatures derived by the proxy approach of Overpeck et al. (1997). The song sheet from which we read the intricacies of the climatic opera is provided of Polyakov et al. (2003), who derived a surface air temperature history that stretches from 1875 to 2000 based on measurements carried out at 75 land stations and a number of drifting buoys located poleward of 62°N latitude. Here's what the team of eight U.S. and Russian scientists found.
From 1875 to about 1917, the surface air temperature of the huge northern region rose hardly at all; but then it took off like a rocket, climbing 1.7°C in just 20 years to reach a peak in 1937 that has yet to be eclipsed. During this 20-year period of rapidly rising air temperature, the atmosphere's CO2 concentration rose by a mere 8 ppm. But then, over the next six decades, when the air's CO2 concentration rose by approximately 55 ppm, or nearly seven times more than it did throughout the 20-year period of dramatic warming that preceded it, the surface air temperature of the region poleward of 62°N experienced no net warming and, in fact, may have actually cooled a bit.
In light of these results, it is difficult to claim much about the strength of the warming power of the approximate 75-ppm increase in the atmosphere's CO2 concentration that occurred from 1875 to 2000, other than to say it was miniscule compared to whatever other forcing factor, or combination of forcing factors, was concurrently having its untrammeled way with the climate of the Arctic.
One cannot, for example, claim that any of the 1917 to 1937 warming was due to the 8-ppm increase in CO2 that accompanied it, even if augmented by the 12-ppm increase that occurred between 1875 and 1917; for the subsequent and much larger 55-ppm increase in CO2 led to no net warming over the remainder of the record, which suggests that just a partial relaxation of the forces that totally overwhelmed the warming influence of the CO2 increase experienced between 1937 and 2000 would have been sufficient to account for the temperature increase that occurred between 1917 and 1937. Understood in this light, CO2 does not even enter the picture.
Since this point is so important, we will state it a second way. The fact that there was no net warming between 1937 and 2000 implies that changes in some other factor or group of factors completely overpowered whatever warming effect might have been produced by the CO2 increase experienced over this period and, possibly, some of the period preceding it. Hence, to account for the increase in temperature that occurred between 1917 and 1937, which was accompanied and preceded by a much smaller increase in CO2, one need only envision an even smaller, but oppositely directed, change in the other factor or group of factors that thwarted the realization of the impetus for CO2-induced warming that may have developed between 1937 and 2000. And, in fact, we truly know that such must have occurred, for there is absolutely no way that a mere 8- or 20-ppm increase in the air's CO2 concentration could ever produce a 1.7°C spike in surface air temperature.
In conclusion, and remembering that the Arctic is the region of the world where the warming effect of the rising atmospheric CO2 concentration is supposed to be most dramatic and, hence, most readily detected, we can honestly say that the historical enhancement of the CO2 greenhouse effect, or whatever is left of it after various negative feedbacks have come into play, must be of such small magnitude as to be of essentially no significance.
And so we repeat the refrain of our prior week's Editorial: Thank goodness for canaries!
Will you sing along with us?
| Sherwood, Keith and Craig Idso |
References
Overpeck, J., Hughen, K., Hardy, D., Bradley, R., Case, R., Douglas, M., Finney, B., Gajewski, K., Jacoby, G., Jennings, A., Lamoureux, S., Lasca, A., MacDonald, G., Moore, J., Retelle, M., Smith, S., Wolfe, A. and Zielinski, G. 1997. Arctic environmental change of the last four centuries. Science 278: 1251-1256.
Polyakov, I.V., Bekryaev, R.V., Alekseev, G.V., Bhatt, U.S., Colony, R.L., Johnson, M.A., Maskshtas, A.P. and Walsh, D. 2003. Variability and trends of air temperature and pressure in the maritime Arctic, 1875-2000. Journal of Climate 16: 2067-2077.