§ Mr. VazTo ask the Secretary of State for the Environment how much carbon dioxide is in the atmosphere now; at what rate carbon dioxide becomes absorbed by plants and plankton; at what rate carbon dioxide is being discharged into the atmosphere; what is his estimate of the amount of carbon dioxide permitted in the atmosphere before an increase in global temperature occurs; when the atmosphere will be saturated by carbon dioxide; and what will be the overall effect.
§ Mr. TrippierThe concentration of carbon dioxide in the atmosphere is currently about 350 parts per million by volume. Land and ocean-based plants are estimated to absorb some 800,000 million tonnes of carbon dioxide annually, which is approximately balanced by the natural annual discharges. Man-made emissions to atmosphere are estimated to be between 18,000 and 25,000 million tonnes of carbon dioxide annually. Any increase in atmospheric concentration of carbon dioxide would be expected to lead to some global warming. The scale of the effect is currently under review by the UNEP/WMO intergovernmental panel on climate change. The measured rise of about 0.5 deg. C in average global temperature in the past 130 years is consistent with model predictions of the increase to be expected as concentrations of carbon dioxide and other greenhouse gases have risen from pre-industrial values. No projections of future man-made emissions lead to saturation of the atmosphere by carbon dioxide.