Uncertainties associated with global effects of atmospheric CO2

Although the evidence is quite clear that the increase in atmospheric CO₂ is at least to a large degree a result of fossil fuel burning, and it is equally clear that this increase will result in some change in the global climate, there are quantitative uncertainties that require additional understanding before full assessments can be made. There are quantitative uncertainties in the natural carbon cycle as well as uncertainties in the behaviour of the various reservoirs when perturbed by man. There are questions about the terrestrial biosphere and about the rate at which the oceans can assimilate and store carbon.There are uncertainties in regard to the climate change that can result from increased atmospheric CO₂. Progress in modelling the atmosphere must continue to narrow these uncertainties before the impacts of climate change on man can be adequately determined.The future demands for fossil fuels are uncertain. The growth of the developing world will be closely linked to fossil energy for the next five to eight decades, and rates of growth in these world segments are dependent on many ill-defined quantities.Only the observed increase in the atmospheric concentration and the present (and recent past) rate of production of CO₂ from fossil fuels provide data without uncertainties.