Global Temperature Charts Suggest Implausibility of UN CO2 HypothesisAlan Carlin | July 25, 2009
On June 30 I appeared on the Glenn Beck show, where I showed two charts from my Comments on the proposed EPA endangerment finding report. Although these two graphs do not prove or disprove the existence of significant global warming as a result of increasing levels of carbon dioxide in the atmosphere (the principal UN hypothesis), they are readily understandable and suggest that substantial such warming from this cause is implausible.
UN Temperature Projections Compared with Measured Global Temperatures
The first graph compares some of the United Nations IPCC model projections (in red, orange, and brown) and actual global temperature surface (green) and satellite (blue) measurements. There is also a yellow line representing the UN’s projection of future temperatures if there were no further human caused carbon dioxide (CO2) emissions. The vertical scale shows temperatures and the horizontal scale calendar years.
It is quite evident that there appears to be an increasing divergence between the UN projections and the global temperature measurements. The obvious question is how this could be if the UN projections are correct. We cannot rule out a brief divergence between projections and temperatures, of course, based on other random and unexplained factors.
But the other seemingly more likely possibility is that the UN projections are substantially inaccurate and exaggerate the projected temperature increase on the high side. Subsequent temperature measurements (not shown here) do not resolve this discrepancy. If the projections are substantially too high, perhaps they do not deserve to be taken as seriously as many people now do.
Decreasing Measured Temperatures and Increasing CO2 Levels
The second graph also shows global temperatures by calendar year for the period 2002 until mid-2008, but superimposes on this chart yearly atmospheric CO2 levels (shown in green) by year. Since there are two principal sources of global temperature data, surface (shown in black) and satellite (shown in red) measurements, both are shown along with trend lines for each. Inspection of the data shows that while temperature data were trending down over this period, CO2 levels were steadily increasing.
This again suggests that either there was a brief, random, divergence from what would be expected if the UN hypothesis concerning the effects of increasing CO2 levels on temperatures are correct, or that the UN models and hypothesis are simply incorrect. The brief divergence possibility appears implausible because very similar divergences have appeared previously during the periods 1880 to 1910 and 1940 to the mid-1970s. In fact, the changes in global temperatures appear to be cyclical and to be very similar to the pattern of the Pacific Decadal Oscillation (PDO) which has roughly a 60 year cycle (with 30 up years followed by 30 down years). This leaves the other possibility–that something may be wrong with the UN’s basic hypothesis that CO2 levels are the major determinant of global temperatures since the UN models do not show any such cycles and do not explain the down years from 1940 to the mid-1970s or since 1998.
And if their hypothesis is incorrect, their proposed solution, decreasing CO2 emissions into the atmosphere, would not be effective in preventing increases in global temperatures. At the very least there would appear to be other important factors influencing global temperatures besides CO2 levels that the UN has not considered. It is important that we understand what these other factors might be before committing ourselves to trying to reduce CO2 emissions at the cost of many trillions of dollars. To proceed now with reducing CO2 emissions would not only be very expensive but possibly largely futile as well.