Alternative assessment of methane’s contribution to the greenhouse effect

Abstract

Methane is one of the greenhouse gases (GHG), the increase in the concentration of which in the atmosphere is of particular concern to environmentalists and climatologists. The main sources of CH4 emissions are the extraction and processing of hydrocarbon raw materials, cattle and sheep breeding, and rice cultivation. To reduce CH 4 emissions, various countries are making commitments aimed at reducing production volumes in their respective sectors of the economy. However, our estimates show that the contribution of methane to global warming accepted by the IPCC is greatly exaggerated. The simplest model of the greenhouse effect, presented in the works of S.M. Semenov, was used as the main tool for theoretical analysis. The values of the GHG absorption spectra are taken from the HITRAN database. The results obtained showed that the greenhouse effect and the formation of the average global temperature of the Earth’s surface are caused almost exclusively by two substances – water and carbon dioxide, while the total contribution of CH 4 and N2O does not exceed 1.4%. The results of the calculations provide grounds for a critical assessment of the widespread opinion about the high risk of current CH4 emissions from the point of view of global warming and the observed climate changes. Anthropogenic emissions of CH4 are estimated to be 9390 million tons per year in CO2 equivalent, or, taking into account the global warming potential of CH4 accepted by IPCC – 375.6 million tons per year. Of these, 30% (112.7 million tons) fall on the cattle breeding. With the complete cessation of milk and beef production, the decrease in the average global temperature due to the reduction of CH4 emissions will be less than 0.04 оC, which does not exceed 2.5% of the target limiting the growth of global warming at a level of no more than 1.5 оC.