The aim of trying to model climate by running simulations squillions of times when we know the system is crazily complex does seem absurd, and indeed liable to produce every possible kind of climate unless carefully tended by high priests who know what to look for to provide illustrations of the man-made CO2-driven climate crisis conjecture.
But we have other angles on the system which might provide more reliable guides as to our impact on it. One of these is the study of the cycles of atmospheric constituents as they move in and out of the airborne phase. These have been done for many elements and compounds, and typically they show high levels of uncertainty about the size and behaviour of sources and sinks. This is true for CO2 as well as the rest. But whereas the simulation models of linked differential equations for the whole climate seemed intrinsically doomed to farce and failure, the lifecycle studies of compounds such as CO2 are surely susceptible to ongoing improvement through increased quality and quantity of observations.
A recent paper by Hermann Harde of the Helmut-Schmidt University in Hamburg has rekindled my interest in this area. The title of his paper is ‘What Humans Contribute to Atmospheric CO2: Comparison of Carbon Cycle Models with Observations’ , and it can be downloaded free of charge from the link.
In a nutshell, he insists that human produced CO2, whether from land-use changes or fossil-fuel consumption, has to be treated alongside ‘natural’ CO2 since mother nature will treat a given molecule type the same, regardless of its origin. This is in contrast to the IPCC which has claimed that human-produced CO2 is accumulating in the atmosphere, and that almost all the increase in recent decades is due to us: ‘With a very high confidence, the increase in CO2 emissions from fossil fuel burning and those arising from land use change are the dominant cause of the observed increase in atmospheric CO2 concentrations.’ (AR5, 220.127.116.11).
Harde’s analysis leads him to conclude that CO2 residence times are the order of a few years, and that these times apply to CO2 from any source. His flow model is basically the swimming-pool one as used by Salby, in which the rate of change of the amount of airborne CO2 is given by the difference between the flux into the air, and the flux out. He develops that further, and makes frequent comparisons with observations. He also examines, item by item, several assertions made in IPCC reports in this area and finds them wanting. For example the above quote from AR5 is said in that report to be supported by 5 arguments. Harde examines each and finds them inadequate as supports.
His conclusions from his own modelling are quite dramatic:
1. the recent increases in CO2 can be explained by a single balance equation, and is the only method yet which does so ‘in complete conformity with all observations and natural causalities’;
2. the human contribution to the recent increases is relatively small, e.g. ‘as an average over the period 2007-2016, the anthropogenic emissions … donated not more than 4.3% to the total concentration of 393 ppm, and their fraction to the atmospheric increase since 1750 of 113ppm is not more than 17ppm, or 15%.’
Is this not an area deserving of more research? But how will it be funded given that the direction of it seems so unfavourable to ‘the cause’? And will the bells announcing a climate emergency of a different kind be ringing soon on board the Climate Consensus?