Reducing Methane Emissions

It is time that our attention is turned to a more potent greenhouse gas called methane
Reducing Methane Emissions
GK Photo

Climate change poses existential risk for the planet Earth as also huge human health risk in the short run. The World Economic Forum estimates 2,50,000 annual losses of life worldwide from 2030, with intensifying exposure to heat, infectious diseases and malnutrition, climate change causing even crop failures. The number of extremely hot days with temperature breaching 50 degrees Celsius, has doubled since 1980. About ten million lives are annually lost to air pollution caused by combustion of fossil fuels. The sooner the world economies opt for renewal energy, the better for the Earth and us. As an immediate measure, however, we would do well to reduce the heat in the atmosphere.

Gases that trap heat in the atmosphere, commonly called greenhouse gases, are mainly Carbon dioxide, Methane, Nitrous oxide and High Global Warming Potential (HGWP) gases. Carbon dioxide enters the atmosphere through burning of fossil fuels (coal, natural gas, and oil), solid waste, trees and other biological materials, and also as a result of certain chemical reactions like manufacture of cement. Carbon dioxide is removed or sequestered from the atmosphere when it is absorbed by plants as part of the biological carbon cycle. This primary greenhouse gas emitted through human activities, accounted for about 80 percent of all U.S. greenhouse gas emissions in 2019. Human activities are altering the carbon cycle – both by adding more CO2 to the atmosphere, and by influencing the ability of natural sinks, like forests and soils, to remove and store CO2 from the atmosphere. While CO2 emissions come from a variety of natural sources, human-related emissions are responsible for the increase that has occurred in the atmosphere since the industrial revolution that began around 1750. In the United States, since 1990, the management of forests and other land has acted as a net sink of CO2, which means that more CO2 is removed from the atmosphere, and stored in plants and trees, than is emitted. This carbon sink offset was about 12 percent of total emissions in 2019. Carbon dioxide is constantly being exchanged among the atmosphere, ocean, and land surface as it is both produced and absorbed by many microorganisms, plants, and animals. However, emissions and removal of CO2 by these natural processes tend to balance, absent anthropogenic impacts. Until now climate change mitigation efforts focused mainly on carbon dioxide have paid off even as these emissions have tapered off in recent years, mostly due to a switch from coal to natural gas.

It is time that our attention is turned to a more potent greenhouse gas called methane, whose atmospheric levels are growing faster than any time in the past two decades, and it’s most likely coming from food production. Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from livestock and other agricultural practices, land use and by the decay of organic waste in municipal solid waste landfills. Nitrous oxide is emitted during agricultural, land use, industrial activities, combustion of fossil fuels and solid waste, as well as during treatment of waste water. Fluorinated gases comprising Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are synthetic, potent greenhouse gases that are emitted in smaller quantities from a variety of industrial processes and are sometimes used as substitutes for stratospheric ozone-depleting substances.

Methane emissions are a double-edged sword inasmuch as the gas traps 28 times more heat than carbon dioxide, and has a shorter lifetime in the atmosphere, making it harder to control. Methane is used to heat our homes, grow our food, create fertilizers and produce things like hydrogen that we use in clean fuel cells. Methane levels in the atmosphere were fairly stagnant in the early 2000s, increasing at a rate of around 0.5 parts per billion annually, said the researchers in an editorial published in Environmental Research Letters. But since 2007, the levels have increased at more than ten times that rate. And the growth rate jumped over 20 times to reach around 10 parts per billion in 2015 and is on the increase ever since.

In an effort to reduce methane emissions, scientists have been investigating two linked questions. First, what are the major sources of methane? Second, where are the worst offenders? Livestock is the largest source, responsible for 31% of the global total, according to Ilissa Ocko at the non-profit Environmental Defense Fund (EDF) in New York City and her colleagues. Oil and gas operations rank a close second, responsible for the next 26%. Other sources include landfills, coal mines, rice paddies and water-treatment plants.

The effect of each gas on climate change depends mainly on three factors: (i) How much of it is in the atmosphere? (ii) How long do these stay in the atmosphere? and (iii) How strongly do they impact the atmosphere? Concentration, or abundance, is the amount of a particular gas in the air. Larger emissions of greenhouse gases leading to higher concentrations in the atmosphere, are measured in parts per million, parts per billion, and even parts per trillion. One part per million is equivalent to one drop of water diluted into about 13 gallons of liquid (roughly the fuel tank of a compact car). Each of these gases can remain in the atmosphere for different durations of time, ranging from a few years to thousands of years. All of these gases remain in the atmosphere long enough to become well mixed, meaning that the amount that is measured in the atmosphere is roughly the same all over the world, regardless of the source of the emissions. Some gases are more effective than others at making the planet warmer and “thickening the Earth’s blanket.”

The reasons for this spike are unclear, the scientists say. That’s because not enough is understood about the global methane cycle: its sources as well as its sinks. Tracking methane emissions is not easy inasmuch as these can come not only from natural sources such as wetlands and lakes but also from human sources such as dams and oil and gas wells. Recent research indicates that two-thirds of global methane emissions come from human activities and most of those sources are agricultural, such as cattle farming and rice paddies, where microbes produce the gas. There is an urgent need to quantify and reduce methane emissions, the Researchers say. Mitigating methane emissions could slow climate change efficiently in a shorter time. The new report lists some possible routes that include detecting and reducing natural gas leaks; covering landfills; modifying cattle diets; and developing farm bio-digesters. “Keeping global warming below 2°C is already a challenging target,” they say. “Such a target will become increasingly difficult if reductions in methane emissions are not also addressed strongly and rapidly.”

Reducing methane from livestock is particularly challenging because of the food habits developed by the people over the ages. They could perhaps be persuaded to eat less meat, but persuading people to change their diet by giving up on meat eating altogether is a very difficult proposition even as it has now been scientifically established that a plant-based diet reduces chronic disease risks and strengthens ecology. The irony is that consumption of meat is rising in low- and middle-income countries in line with rising incomes. It may be easier to curb emissions from other sectors though. In many cases, doing so wouldn’t cost anything and it could even be profitable.

Bhushan Lal Razdan, formerly of the Indian Revenue Service, retired as Director General of Income Tax (Investigation), Chandigarh

Disclaimer: The views and opinions expressed in this article are the personal opinions of the author. The facts, analysis, assumptions and perspective appearing in the article do not reflect the views of GK

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