Rapid action to abate methane needed

Rapid reductions in emissions of methane and other short-lived greenhouse gases are needed to slow down global warming, especially in the Arctic region.

Methane emissions are the second largest cause of global warming, after carbon dioxide (CO2). Like CO2, methane emissions anywhere create warming everywhere.

While less abundant in the atmosphere than CO2, ton-for-ton, methane traps 25 times more heat than CO2 over a 100-year period. Measured over 20 years, methane’s warming impact is 72 times greater than an equivalent weight of CO2. Because methane survives in the atmosphere for only 8–12 years (compared to more than a century for CO2), substantial emission cuts today will diminish concentration levels within one to two decades – an important time frame for slowing warming in regions that may reach critical thresholds or “tipping points” that affect the global climate system or large human populations, such as those in the Arctic and the Himalayan region.

Over the past 100 years, the Arctic has warmed at over twice the rate of the rest of the globe, and rapid loss of Arctic sea ice has already occurred. Seabed and permafrost release of methane and CO2 from such ice and tundra melting could further accelerate warming of the entire globe. Sea level rise from increased melting of the Greenland ice sheet and Arctic glaciers, even of only a few decimetres, would endanger millions throughout the world with additional flooding.

So the rapid warming of these sensitive regions will have global effects, making the long-term battle against global warming that much harder.

Reductions in CO2 and other long-lived gases clearly must serve as the backbone of any meaningful effort to reduce global climate change. More than anything else, global warming drives Arctic warming. But preservation of the Arctic and land glaciers will in addition require means that act more rapidly.

Shorter-lived climate pollutants may provide one such means. Some research indicates that three short-lived pollutants – black carbon, ozone, and methane – have had nearly the same temperature impact on the Arctic as CO2 over the past century. Since they have such short lifetimes – from a few days for black carbon, to a decade for methane – reductions in these pollutants would show a more rapid Arctic climate response than could occur from CO2 reductions alone.

Methane abatement is readily available. As a well-mixed greenhouse gas, methane reductions anywhere will slow Arctic warming, and relatively quickly.

Also of great importance, not least to developing countries, is the fact that methane reductions significantly reduce air pollution and smog by reducing ground-level (tropospheric) ozone. Such ozone-related smog already causes tens of thousands of deaths annually, and millions of respiratory disease symptoms, as well as significant crop damage that decreases food production. These figures are forecast to grow exponentially as countries industrialize.

Measures that address methane also make good sense from a development perspective. Landfills and wastewater treatment plants set up to capture methane from the beginning result in significant health, energy and economic co-benefits. Even small-scale methane projects, such as those that capture methane for biogas from just a few livestock, can bring significant development benefits to rural areas.

Methane reductions provide additional climate benefits in the Arctic by also reducing ozone there, which otherwise blankets the Arctic with smog in the springtime, hastening Arctic spring ice melt.

In addition, many measures that reduce methane also reduce other climate forcers, not only long-lived gases such as CO2 but short-lived forcers not covered by any current climate agreements, such as ozone and black carbon. For example, a methane project that produces biogas locally for cooking, heating or transport would also reduce CO2 and black carbon emissions that would otherwise result from the burning of wood, dung or coal for these purposes.

More than half of the earth’s methane output comes from human-related sources – primarily in the areas of agriculture (livestock and rice cultivation), waste management (landfills, sewage treatment, and manure), and energy (coal and oil/gas production).

According to the US Environmental Protection Agency (EPA), global methane emissions from human-related sources could rise 23 per cent from 2005 to 2020 – totalling 7.9 billion tons of CO2-equivalents.

Studies by the International Institute for Applied Systems Analysis (IIASA) and the US EPA have shown that global methane reductions of up to 40 per cent, or 2.7 billion tons CO2-equivalents, of the projected global emissions in 2020 are available at costs of under 40 euros/ton, with up to 15 per cent at negative cost (i.e. self-paying). The low-cost abatement options include measures at sources such as coal mines, oil and gas pipelines, landfills, wastewater facilities, and animal waste.

Regulation eventually may serve as the main path for future methane abatement, particularly as regards common public sector sources of methane such as landfills and wastewater treatment facilities. Today however, few non-OECD countries – and not even all OECD members – ban the venting of methane.

In the absence of regulation, the Clean Development Mechanism (CDM) has so far been the primary market-based incentive to capture and utilize methane. Methane abatement represents around 15 per cent of all CDM projects under development, or 600 projects globally, which together could reduce up to 100 million tonnes of CO2-equivalents per annum, or about four per cent of the reduction potential identified by IIASA.

The creation of a stand-alone global methane fund dedicated to moving forward global methane projects as rapidly as possible is being proposed. It is foreseen that such a fund would work in concert with the CDM, the US EPA’s Methane to Markets programme, and multilateral institutions.

Sources: A fast-action plan for methane abatement (December 2009). Published by the Clean Air Task Force, Climate Policy Center-Europe and Clean Air-Cool Planet.
Methane: Tapping the untapped potential (December 2009). By A. Pettus. Published by the Clean Air Task Force. Available at: www.globamethanefund.org or www.catf.us

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