Technical potentials and costs for reducing global anthropogenic methane emissions in the 2050 timeframe –results from the GAINS model

Abstract

Methane is the second most important greenhouse gas after carbon dioxide contributing to humanmade global warming. Keeping to the Paris Agreement of staying well below two degrees warming will require a concerted effort to curb methane emissions in addition to necessary decarbonization of the energy systems. The fastest way to achieve emission reductions in the 2050 timeframe is likely through implementation of various technical options. The focus of this study is to explore the technical abatement and cost pathways for reducing global methane emissions, breaking reductions down to regional and sector levels using the most recent version of IIASA's Greenhouse gas and Air pollution Interactions and Synergies (GAINS) model. The diverse human activities that contribute to methane emissions make detailed information on potential global impacts of actions at the regional and sectoral levels particularly valuable for policy-makers. With a global annual inventory for 1990-2015 as starting point for projections, we produce a baseline emission scenario to 2050 against which future technical abatement potentials and costs are assessed at a country and sector/technology level. We find it technically feasible in year 2050 to remove 54 percent of global methane emissions below baseline, however, due to locked in capital in the short run, the cumulative removal potential over the period 2020-2050 is estimated at 38 percent below baseline. This leaves 7.7 Pg methane released globally between today and 2050 that will likely be difficult to remove through technical solutions. There are extensive technical opportunities at low costs to control emissions from waste and wastewater handling and from fossil fuel production and use. A considerably more limited technical abatement potential is found for agricultural emissions, in particular from extensive livestock rearing in developing countries. This calls for widespread implementation in the 2050 timeframe of institutional and behavioural options in addition to technical solutions.

Reducing global air pollution: the scope for further policy interventions

“…A comprehensive clean air policy that would also aim at ground-level ozone would need to include CH 4 and CO mitigation in its portfolio, especially in view of the past increases in hemispheric ozone levels that have been attributed to growing CH 4 emissions [71]. From such a perspective, measures that reduce only CH 4 but would not affect PM precursor emissions could cut global CH 4 by more than half in 2040 [72].…”

Electricity savings and greenhouse gas emission reductions from global phase-down of hydrofluorocarbons

“…Hence, the mitigation scenarios developed here assume the same demand for cooling services as in the respective baselines but with the consumption of high-GWP HFCs replaced by alternative low-GWP technologies. The choice and order of adoption of technologies in a given sector are determined by marginal abatement cost curves estimated on the basis of baseline HFC consumption (Höglund-Isaksson et al, 2017). For descriptions of key drivers at the sectoral level, source-specific emission factors and implemented control policies, see the supplementary material of Purohit and Höglund-Isaksson (2017).…”

“…The baseline scenarios improve upon those presented in Purohit and Höglund-Isaksson (2017) and Höglund-Isaksson et al (2017) not only by extending the scenarios to 2100, but also by making use of the information on historical HFC consumption by sector and HFC species that has recently become available at increasingly greater detail from the national reporting to the UNFCCC. The principal information sources used to estimate historical HFC consumption and emissions are as follows: (1) robust historical HFC consumption data by sector (2005, 2010, and 2015) for developed countries derived from their UNFCCC National Inventory Submissions (UNFCCC, 2017); (2) historical HFC consumption data for China and India and with some additional information for other developing countries from various national and international sources 3 ; (3) data on historical HCFC consumption from UNEP (2017a), part of which has been replaced by HFCs; and (4) assumed effective control of HFC-23 (CHF3) emissions from the manufacture of HCFC-22 (CHClF2) in China (Simmonds et al, 2017; and India (GoI, 2016;Say et al, 2019).…”

“…The key contribution of this task is not to determine the reduction levels in HFC consumption (as these are already predetermined by the regional targets of the KA and by the almost complete reductions possible under the maximum technically feasible reduction -MTFR) but rather to investigate the content of the HFC phase-down in terms of the order and extent to which various alternative technologies are picked up in the different sectors and regions. This is important as it is only by understanding the content of the low-GWP technology uptake that we can get an idea of the expected degree of employment of different technologies and their respective contributions to electricity savings and reductions in GHGs and air pollution, which tend to differ by region, sector, and technology (Höglund-Isaksson et al, 2017).…”

“…The Greenhouse gas-Air pollution Interactions and Synergies (GAINS) model developed by the International Institute for Applied Systems Analysis (IIASA) has previously been used to produce detailed future scenarios for HFC emissions extending to 2050 (Höglund-Isaksson et al, 2017;Purohit and Höglund-Isaksson, 2017), which have fed into cli-1 Ninety-five signatories have ratified the Kigali Amendment to the Montreal Protocol on phasing down HFCs worldwide, as of 12 June 2020 (UN, 2020).…”