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12 June, 2019 11:14:49 AM
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Fight climate change

Methane is a complicated gas to predict and manage since it is released from multiple sources
Mohammed Abul Kalam, PhD
Fight climate change

The World Environment Day was observed on June 5 in Bangladesh and the rest of the world through various events to reinforce awareness of critical environmental issues. Forty-five, the United Nations’ World Environment Day, was first celebrated. Throughout the world, on June 5, efforts are made at creating greater awareness of environmental issues and finding solutions to the world’s most pressing climate-related problems. Since 1974, the day has increasingly assumed global significance, with country after country realising the import of a joint natural heritage that transcends borders. Glass ceilings have been shattered and information is easily accessible to everyone. The climate change is a reality, and it is a global problem. At the national level, we have several climate change funds to deal with the adverse effects of global warming, including the Bangladesh Climate Change Trust Fund and Bangladesh Climate Resilience Fund (The Independent, Saturday 8 June 2019).

Greenhouse gas emissions have been increasing now for two centuries. Damage to the atmosphere is already profound enough that reducing emissions alone won’t be enough to avoid effects like extreme weather and changing weather patterns. On reducing greenhouse gas emissions, particularly those of carbon dioxide, the major contributor to climate change and long-lived greenhouse gas reducing emissions should remain the paramount climate goal.

The methane menace: After carbon dioxide, methane is the second most important greenhouse gas leading to human-induced climate change. Methane packs a climate punch: it is 84 times more powerful than carbon dioxide in warming the planet over the first 20 years of its molecular life.

Methane is already the second most abundant greenhouse gas that is released from human activities. “Natural gas”, for instance, refers to a mixture dominated by methane. It has become steadily more concentrated in the air since the 18th century, more than doubling from around 750 parts per billion (ppb) to more than 1,850 ppb today. Like carbon dioxide, methane absorbs infrared radiation and warms the atmosphere. Although there is much less methane in the air than CO₂, the strength of that absorption is such that per molecule it is around 25-30 times more potent as a greenhouse gas.

It is a complicated gas to predict and manage since it is released from multiple sources. Some are natural processes, such as emissions from wetlands and bogs, methane that bubbles up through the ocean, or even through termite farts. But many different human activities also result in methane being released. Flooded rice paddies produce lots of methane, as do cow and sheep stomachs, while the gas is also released from waste buried in landfills.

Oil and gas producers and distributors make estimates of their emissions based on complex calculations that account for amounts lost during activities such as drilling, venting and flaring, plus any gas that seeps out from the millions of joints, pipes, and connectors that make up the natural gas network. These estimates are then supplemented by in-field tests, spot-checking and monitoring for emissions near the source.

Scientists have also measured plumes of natural gas as they waft away from oil and gas installations using aircraft, and have detected methane over large areas from satellites. In general, these sorts of research methods have shown more methane is being emitted than industry-reported figures.

Natural gas is not pure methane – it also contains small amounts of other hydrocarbons, such as ethane or propane. However, unlike methane, these gases have relatively few other anthropogenic sources, so act as excellent tracers of methane from the fossil fuel industry.

Methane and the other hydrocarbons in natural gas, like ethane and propane, also create ozone pollution in the lower atmosphere when mixed with nitrogen oxides from combustion. Ozone harms people by causing the muscles in the airways to constrict, aggravating lung diseases such as asthma, emphysema and chronic bronchitis. It also limits plant growth and reduces crop yields.

Methane emissions from human activities are now larger than all natural sources combined. Agriculture and energy production generate most of them, including emissions from cattle, rice paddies and oil, and gas wells.

The result is methane concentrations in the atmosphere have increased by 150% from pre-industrial times, and continue to grow. Finding ways to reduce or remove methane will, therefore, have an outsize and fast-acting effect in the fight against climate change.

Pre-industrial baseline: The Industrial Revolution began in the late 1700s in Britain and spread around the world. But this only marked the beginning of a gradual rise in our greenhouse gas emissions. Various studies have found climate change signals appearing on a global scale as early as the 1830s, or as recently as the 1930s.  Besides the evolving and increasing human influence on the climate, we also know that plenty of other natural factors can affect earth’s temperature. This natural variability in the climate makes it harder to determine a single precise pre-industrial baseline. Scientists separate these natural influences on the climate into two groups: Internal and external forcing. Internal forcing transfers heat between different parts of earth’s climate system. The El Nino-Southern Oscillation, for example, moves heat between the atmosphere and the ocean, causing year-to-year variations in global average surface temperatures of about 0.2℃. Similar variations also happen on decadal timescales, which are associated with slower energy transfers and longer variations in earth’s temperature. External forcing comes from outside earth’s climate system to influence global temperature. One example of an external forcing is volcanic eruptions, which send particles into the upper atmosphere. This prevents energy from the sun reaching earth’s surface and leads to a temporary cooling.

Another external influence on earth’s climate is the variability in the amount of energy the sun emits. The sun’s total energy output varies on multiple cycles and is related to the number of sunspots, with slightly higher temperatures when there are more sunspots, and vice versa.

Earth has experienced extended periods of cooling due to more frequent explosive volcanic eruptions and periods of few sunspots – such as during the “Little Ice Age” which lasted roughly from 1300 to the 1800s. All of these factors mean that earth’s climate can vary quite substantially even without human interference. It also means that if we choose a pre-industrial baseline when there was low solar activity, like the late 1600s, or in a period of high volcanic activity, like the 1810s or the 1880s, then we would have a lower reference point and we would pass through 1.5℃ or 2℃ sooner.

Cost of pollution: The difference between stock and flow pollutants is shown in the figure below. Flow pollutant emissions, for example of methane, do not persist. Emissions in period one and the same emissions in period two lead to a constant (or roughly constant) amount of the pollutant in the atmosphere (or river, lake, or sea).

With stock pollutants, such as carbon dioxide, concentrations of the pollutant accumulate as emissions continue. The flow and stock pollutants are over time. In the first period, one unit of each pollutant is emitted, leading to one unit of concentration. After each period, the flow pollutant decays, while the stock pollutant remains in the environment.  The economic theory of pollution suggests different approaches to greenhouse gases with long or short lifetimes in the atmosphere. The social cost (the cost society ought to pay) of flow pollution is constant over time because the next unit of pollution is just replacing the last, recently decayed unit.

This justifies a constant price on flow pollutants. In the case of stock pollutants, the social cost increases with constant emissions as concentrations of the pollutant rise, and as damages rise, too.  Improving the environmental integrity of climate policy: This could take several forms. For some countries, it may be that the new approach provides a better way of comparing different gases within a single-basket approach to greenhouse gases, as in an emissions trading scheme or taxation system. For others, it could be used to set separate but coherent emissions targets for long- and short-lived gases within a two-basket approach to climate policy. Either way, the new approach means countries can signal the centrality of carbon dioxide reductions in their policy mix while limiting the warming effect of shorter-lived gases.

The new way of using global warming potentials demonstrably outperforms the traditional method in a range of emission scenarios, providing a much more accurate indication of how stock and flow pollutants affect global temperatures. This is especially so under climate mitigation scenarios.

Well-designed policies would assist sectoral fairness within countries, too. Policies that reflect the different roles of stock and flow pollutants would give farmers and rice growers a more reasonable way to control their emissions and reduce their impact on the environment, while still acknowledging the primacy of carbon dioxide emissions in the climate change problem.

An ideal approach would be a policy that aimed for zero emissions of stock pollutants such as carbon dioxide and low but stable (or gently declining) emissions of flow pollutants such as methane. Achieving both goals would mean that a farm, or potentially a country, can do a better, clearer job of stopping its contribution to warming.

Future research and development will determine the technical and economic feasibility of methane removal. Even if successful, methane- and other carbon-removal technologies are no substitute for strong and rapid emissions reductions if we are to avoid the worst impacts of global warming.

The writer is former Head, Department of Medical Sociology,

Institute of Epidemiology, Disease Control & Research (IEDCR)

Dhaka, Bangladesh

E-mail: med_sociology_iedcr@yahoo.com

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Published by the Editor on behalf of Independent Publications Limited at Media Printers, 446/H, Tejgaon I/A, Dhaka-1215.
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Editor : M. Shamsur Rahman
Published by the Editor on behalf of Independent Publications Limited at Media Printers, 446/H, Tejgaon I/A, Dhaka-1215.
Editorial, News & Commercial Offices : Beximco Media Complex, 149-150 Tejgaon I/A, Dhaka-1208, Bangladesh. GPO Box No. 934, Dhaka-1000.

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