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NASA Finding throws light on Rising Global Methane Emissions

Global methane emissions have been markedly increasing in recent years, with a large contributor being emissions from the global oil and gas industry. It is estimated that methane emissions globally have been increasing by a massive 25 teragrams per year since 2007. However, a problem was posed in breaking down this number between emissions from the oil and gas industry and other sources such as that released by microbes. This led to much uncertainty in the scientific community over the reasons for this surge in methane emissions.

Rising Methane Emissions & NASA’s Finding

Adding the increasing amounts of methane emissions from the oil and gas industry to that from other sources, it was reported that the total came to be higher than the total levels actually measured in Earth’s atmosphere. National Aeronautics and Space Administration (NASA) however, in a paper published in Nature Communications points out that a third factor is involved after analysis of satellite data, chemical analyses and measurements at the ground level from various sources. The factor, NASA concludes, is that between 2007 and 2014, there was a decrease in total global area burnt due to fires due to which there was a decrease in methane emitted due to releases from burning (Worden et al., 2017).

Between the early 2000s and the 2007-2014 period, satellite observations point towards the fact that there has been a 12 per cent decrease in the area burned globally. In the final analysis Dr Worden and his team estimate that 17 teragrams of the increase in methane is contributed by fossil fuels, 12 teragrams from other sources like from rice farming or wetlands, while decreasing incidences of fires are decreasing the amount of methane added by about 4 teragrams per year. Placing the three statistics together, the amounts emitted combine to match the observed increase in methane emissions of 25 teragrams per year (BBC, 2018). This nevertheless is a massive amount of methane emitted and lead many to ponder over its important implications for control and mitigation of methane emissions and the possible impacts on global warming.

Rising Atmospheric Methane Levels and Mitigation of Anthropogenic Methane Emissions

Methane is the most common greenhouse gas emitted on the Earth after carbon dioxide and accounts for about 14 per cent of global greenhouse gas emissions. Although the quantities of methane emitted in to the atmosphere is fairly less than that of carbon dioxide, its ability to trap heat in the atmosphere is 25 times greater than that of carbon dioxide (Global Methane Initiative, undated). Methane thus is a very potent greenhouse gas and the massively increasing levels of methane in the Earth’s atmosphere should be a cause of major concern for climate watchers.

Le Fevre (2017) lists three principal types of methane emissions: (1) biogenic (2) thermogenic and (3) pyrogenic. Biogenic methane emissions can consist of emissions from landfills, cows, rice paddies and wetlands for example. Thermogenic emissions can consist of natural seeps such as from oceans, or from exploration and production activities and from fossil fuels along with human activities related to these. Pyrogenic emissions result out of incomplete combustion of biomass such as in forest fires for example, or that of fossil fuels or biofuels for instance. Among these a distinction can be made between natural and anthropogenic emissions. About 50 per cent of global anthropogenic methane emissions in 2010 came from 5 sources – oil and natural gas systems, coal mines, agriculture, landfills and wastewater (Global Methane Initiative, undated). Mitigation of anthropogenic emissions of methane is more feasible than natural emissions and requires a source-specific approach depending upon the nature of methane emissions.

In the oil and gas systems mitigation efforts for methane emissions could include equipment or technological upgrades along with efficient practices for emissions management that can make use of emissions reduction technologies. Methane emissions from coal mines can make use of degasification wherein holes are drilled to capture methane instead of venting within mining operations or utilize ventilation air methane (VAM) abatement that involves oxidization of low concentrations of methane for generating heat or electricity. Methane emissions from landfills can be regulated by using wells and a vacuum system that directs the collected gas to a point where it can be extracted for beneficial uses. Wastewater methane emissions can utilize biogas capture systems, anaerobic sludge digestion, centralized aerobic treatment facilities, or gas capture and combustion systems. Methane emissions in agriculture can similarly utilize anaerobic lagoons that can be used to transmit methane to a dedicated point for beneficial uses or otherwise use digesters for compaction or digestion of organic waste thus utilizing methane emissions in a beneficial manner (Global Methane Initiative, undated). As such the nature of methane emissions in a source-specific approach can produce different methods of mitigation.

In many instances methane can also be emitted from industrial processes not as a concentrated stream but through leaks, ruptures, vents, dispersion and accidents. Controlling methane emissions wholesomely therefore poses a difficult prospect. Much of the difficulty in controlling methane emissions and in utilizing methane emissions for beneficial uses lies in the fact that capturing these emissions can be more costly and demand greater technological investments than for some other pollutants. The profitability of the captured methane for producers might also be dependent on a variety of factors including sunk costs to be incurred on capital investments, market prices, availability of technologies, the nature of the releases themselves and so on (Lattanzio et al., 2016). Mitigating methane as a potent greenhouse gas becomes even more important when we consider that herein, a cost-benefit analysis is involved that requires significant capital investment from producers. An ‘infrastructural setup’ is required at various locations that can act to mitigate the problems of cost or technology that can arise in the mitigation of methane emissions. Such an exercise itself requires as a first step fixing a budget for mitigating methane emissions.

Global Methane Emissions

Fig: The Global Methane Budget (2003-2012)
Source: The Global Carbon Project

Fortunately, a step towards an answer is provided by scientific observations in fixing what is called the global methane budget. In fixing the differential increase or decrease in atmospheric methane due to the difference between total emissions as against the total sinks for methane, the global methane budget provides a tool with which estimates can be made on the scale and nature of efforts required in mitigation of methane emissions. In a study by Saunois et al. (2016) over measuring the global methane budget for the period between 2003 and 2012, global methane emissions were estimated at 558 teragrams per year, with a range of 540-568 teragrams. Out of this about 60 per cent of global emissions were anthropogenic. Total sinks for the period between 2003 and 2012 accounted for 548 teragrams with a range of 529-555 teragrams of methane. Thus in measurements for the global methane budget for the period between 2003 and 2012 (taking into account the difference between total emissions and total sinks), methane emissions were increasing at 10 teragrams per year.

The dataset used by NASA for an increase in methane emissions since 2007 by 25 teragrams per year is a marked increase in methane emissions since those found in measurements between 2003 and 2012. Concentrations of methane emissions in the atmosphere are growing at a faster rate in the contemporary decade than in previous decades. A team of international scientists has reported in the journal Environmental Research Letters in 2016 that atmospheric methane concentrations began to show a marked increase at around 2007 and showed precipitous growth in 2014 and 2015, with atmospheric concentrations going up by more than 10 parts per billion annually in these two years (Phys.org, 2016). Since then the scientific community had been looking for answers for emission sources for the methane surge, which NASA’s findings concluded recently.

In this many worry over the effects that these rising amounts of methane emissions might have on global warming as part of a movement towards focusing attention globally on rising methane levels. The rising levels of methane emissions globally occur along with a flattening out of carbon dioxide emissions in recent years. Many hope that mitigation of methane emissions can occur along side mitigation efforts towards carbon dioxide. The bulk of methane emissions (60 per cent) come from anthropogenic sources, and given that methane emissions from all sources are difficult to track, attention can be paid to mitigating anthropogenic sources of methane emissions. The difficulties faced by the scientific community in ascertaining sources of methane emissions only point towards this fact.

Endnote

NASA’s recent finding tracking sources of atmospheric methane emissions points towards the difficulties posed by the prospect of tracking sources of methane emissions. Mitigating anthropogenic sources is a feasible option, yet there are difficulties even in this aspect. Many issues can arise over costs and technological investments in controlling methane emissions at their sources or in putting them to beneficial uses. In this an ‘infrastructural setup’ is required at various locations as a policy measure that can act to mitigate the problems that can arise in the large scale mitigation of methane emissions. The global methane budget along with more accurate and fine tuned findings, therefore, can act as a guide to directing policy in controlling methane emissions.

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