The potential contribution of methane emission reductions

Current climate policies underestimate the potential contribution of methane emission reductions

The current rules of accounting (commitments, flex mex) induce a systematic under estimation of CH4 potentials in mitigating climate change:
The current equivalent between CO2 and CH4 (21) integrates the radiative forcing efficiency and the lifetime of both gazes for a period of 100 years. Taking into account the last IPCC conclusions on climate sensitivity, and the short and medium term trends leading to a probable overshoot over the coming two decades, it is worth considering that the GWP of methane becomes 72 for a period of 20 years, 42 for 50 years.
Scientists obviously know this, but have considered until now that long term GWP equivalent is of safer use, taking into account the cumulative, long term nature of climate change: a short term, higher equivalent may lead to prioritizing action on CH4 instead of CO2, with negative long term consequences. Based on this long term GWP, policy was supposed to be driven by a cost efficient approach of mitigation costs, expressed per avoided ton of CO2 equivalent.
But the political economy of both the international negotiation and domestic policy developments provide new evidence that force us to reconsider this position.

The nature of mitigation actions reinforces the long term significance of methane:
Short and mid term mitigation potentials include CH4 leakage reduction in the energy sector, and the improvement of water and solid waste management. Both are investment decisions, leading to permanent (at least long term) emission reductions. If we compare two investment programs leading to long lasting CH4 and CO2 (say, a CCS coal plant) emission reductions respectively, the tons reduced in the CH4 program are worth 81 tons of CO2 after 20 years, 57 tons of CO2 after 50 years, and 39 tons of CO2 after a hundred years.

The issue today is not just about optimizing between CH4 and CO2 action under economic constraint, but about maximizing domestic climate program impacts under a set of economic, political and technical constraints:
Typically CO2 mitigation programs find a limit in the current stage of technologies and the inertia of infrastructure reorganization (or, conversely, the political acceptance of programs that would impose a drastic restriction on the use of energy services in the absence of low carbon technology and infrastructure). US or EU government are certainly committed now to implementing ambitious action, but the effective outcomes in terms of CO2 emissions will partially be delayed. CH4 mitigation action addresses different economic sectors, mobilizes different technologies and opens a window for new political opportunities.

The Annex B debate on comparability cannot be solved unless new flexibilities are considered:
A first, promising approach is to release the short term constraint by negotiating already two commitment periods (2013-2020 and 2021-2028), a time horizon comparable to the KP when adopted (1997-2012). But the logical, complementary option is to take stock of the unavoidable overshoot that will result from the current level of pledges for 2020 targets and to envisage a set of more ambitious, complementary actions on methane emissions.

TO FIND OUT MORE

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"Reducing Methane Emissions, the other climate change challenge" by B. Dessus and B. Laponche (AFD working paper n°68), present the scientific rationale that justify a new approach to methane emissions, and offers a first evaluation of the possible consequences in terms of policy development in both industrialized and developing countries. >> Read the working paper