Int. J. Environ. Res. Public Health 2011, 8 995 therefore these IPCC assumptions are not scientifically valid assuming that Segalstad‘s data and analyses of them are correct. 13C/12C isotope ratios are usually expressed as 13C values, defined as the standard-normalized difference from the Pee Dee Belemnite (PDB) standard and calculated as follows [13]: 13C /12Csample 1)  1000  13CSample = ( 13C /12CPDB This value is expressed in parts per thousand or per mil (―0/00‖). Using an isotopic mass balance analysis, Segalstad [8,10] finds that CO2 from burning fossil fuel constitutes only at most 4 percent of atmospheric CO2 and that the RT for CO2 in the atmosphere is only a little over 5 years. Essenhigh‘s research [14] supports some of these findings according to Segalstad [12], who describes his methodology as follows [15]: ―The December 1988 atmospheric CO2 composition was computed for its 748 GT C 15 (GT = 10 g) total mass and 13C = –7.807 for 3 components: (1) natural fraction remaining from the pre-industrial atmosphere; (2) cumulative fraction remaining from all annual fossil-fuel CO2 emissions; (3) carbon isotope mass-balanced natural fraction. The masses of component (1) and (2) were computed for different atmospheric lifetimes of CO2.‖ A more recent reference is [16]. Slide 19 of [8], which Segalstad entitles ―Proof from Isotopic Mass Balance,‖ summarizes his results. His slide relates atmospheric CO2 lifetime to atmospheric CO2 mass in the atmosphere by the three components listed above by him. In his Slide 18 Segalstad [8] presents data showing that the expected 13C value, if 21 percent of atmospheric CO2 comes from burning fossil fuels and CO2 has a long lifetime in the atmosphere, would be −11, which he points out is inconsistent with the real world measurements shown in his Slide 19 [8] of −7.807 in December, 1988 as well as in [17]. This is an example of a prediction based on IPCC findings/assumptions that does not correspond to a real world observation, assuming that Segalstad‘s data and analysis are correct. Finally, Segalstad‘s Slide 20 in [8] shows that the CO2 from fossil fuel sources constitutes less than 4 percent of total atmospheric CO2, rather than the 21 percent used by the IPCC [8]. Segalstad‘s findings are bolstered by several other real world observations. One is that climate researchers have long been mystified by the fact that the Mauna Loa CO2 measurements can only account for about half of the anthropogenic emissions (as shown in Figure 1), so they have long sought a ―missing sink‖ for CO2. Interestingly enough, Segalstad‘s analysis shows why this may have occurred, as shown in his slide 21 of [8], where RTs in the range of 50 to 200 years would result in about half the mass of CO2 in the atmosphere, as shown by the red circle in his Slide 21, which is remarkably consistent with the ―missing sink‖ that many researchers have looked for in vain. The existence of this problem is another failed prediction of the IPCC hypotheses. The other finding is that dozens of researchers using a variety of techniques have found RTs that are roughly consistent with the 5–6 year time frame, as shown in Figure 2.