The Case for Contraction and Convergence
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of the oceans. Consequently the airborne fraction of emissions is increasing too. In the analogy, the tap is opening wider, the pressure behind it is increasing, the plughole is blocking up, the rate at which the bath is filling is accelerating and there are more and more people in the bath wanting to fill it. The likelihood of the bath overflowing is itself rapidly growing. PRESENT CO2 ‘PATH INTEGRALS’ – EVIDENCE OF ‘AGGRAVATED RATES OF ACCUMULATION’ OF ATMOSPHERIC CO2 Covering the last two hundred years, good data exist for both CO2 emissions from burning fossil fuel and atmospheric CO2 accumulation, or concentrations in parts per million by volume (ppmv) and weight in gigatonnes (GTC). One part per million by volume of CO2 in the global atmosphere equates to a weight in carbon of 2.13 billion tonnes (gigatonnes). Observed data from the Mauna Loa Observatory (MLO) of the US Government7 shows that the ‘Constant Airborne Fraction’ (CAF) of emissions now appears to be changing. On average the fraction of emissions from fossil fuel burning being retained in the atmosphere is growing, as is shown in Figure 4. The more recent trend in the raw data are shown in the two panels of Figure 5. These data make it possible to determine the effect of having the higher – or ‘aggravated’ – rates of atmospheric CO2 retention persist into the future. These are shown in the projections from the C&C model in the charts C1 (convergence by 2020), C2 (convergence by 2040) and C3 (convergence by 2040) that are in Figure 9. The rate of increase in atmospheric CO2 until recently has been 1.5 ppmv per annum: the carbon weight of this annual increase is therefore approximately 3.3 GTC. This is around half the weight of annual emissions which is currently about 6.5 GTC. The point of great concern here is that over the period 2003–5, the rate of atmospheric increase has jumped to nearer 3 ppmv per annum. This gives a loading of the atmosphere by weight that is roughly equal to, not half, but all the emissions from fossil fuel burning. This suggests that roughly the equivalent of 100 per cent of emissions were retained in the atmosphere in these years. This is ‘aggravated accumulation’.
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