Chapter 5: Anthropogenic methane sources, emissions and future projections

This chapter reviews recent global assessments of anthropogenic methane emissions, their expected future development and estimated reduction potentials. Because methane is a gas which mixes rapidly in the global atmosphere, it is of interest to review emissions at the global scale as well as for the area covered by the eight Arctic nations. The following key findings have been identified: • Bottom-up emission inventories agree fairly well in terms of the overall magnitude of global anthropogenic methane emissions in recent years, that is, about 300 Tg CH4 in 2000 and between 320 and 346 Tg CH4 in 2005. However, the relative contributions from the different source sectors differ markedly between inventories, which can be taken as an indication of high uncertainty within existing emission inventories despite the relatively close agreement between them in terms of total emissions. • Without further implementation of control policies addressing methane than currently adopted, global anthropogenic methane emissions are estimated to increase to between 400 and 500 Tg CH4 in 2030 and between 430 and 680 Tg CH4 in 2050. Primary drivers for the expected emission increase are increased coal production in China and extended shale gas extraction in the USA and Canada, activities which are known to release fugitive methane emissions. • With maximum technically feasible implementation of existing control technology, the estimated reduction potential for global anthropogenic methane emissions amounts to about 200 Tg CH4 in 2030, which is almost 50% below baseline emissions. The control technologies assessed to have the greatest reduction potentials are extended recovery of associated gas from oil production, control of fugitive leakages from gas production, transmission and distribution, extended separation, recycling and treatment of biodegradable waste instead of landfill disposal, extended pre-mining degasification of coal mines, and the implementation of ventilation air oxidizers on shafts from underground coal mines. • External factors, in particular the development of the future price of gas, could have significant effects on the future cost of reducing methane emissions and on the need for further policies to stimulate such reductions. The reason is that many measures to reduce methane emissions involve gas recovery or reduced gas leakage, which means potential opportunities to utilize the recovered gas as a source of energy. • With current policies addressing methane emissions, the eight Arctic nations are estimated to contribute about a fifth of global anthropogenic methane emissions. • As a single world region, the eight Arctic nations emit more anthropogenic methane and have a larger technical abatement potential than any other major world region (e.g. Latin America, Middle East, Africa or China). • The maximum technically feasible reduction of anthropogenic methane in Arctic nations in 2030 is estimated at 63% below baseline emissions or about a quarter of the entire global reduction potential. Within this reduction potential, measures related to fugitive methane emissions from shale gas extraction in the USA and Canada, reduced venting of associated gas from oil production in Russia, and reduced leakage from gas pipelines and distribution networks in all three countries, have the greatest potential to contribute to reduced methane emissions in Arctic nations.

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