How many kinds of greenhouse gases are there? In the midst of the global crisis, the global warming, we are always aware of greenhouse gases. Perhaps, the most familiar greenhouse gas is the carbon dioxide. We are informed about the impact of carbon dioxide through various mass media, such as carbon footprint, carbon neutrality, and carbon credit. This is because carbon dioxide is the highest contributor to global warming. However, another gas that has a great impact as much as carbon dioxide is methane. This article talks about methane.
Methane (CH4) is defined by the Kyoto Protocol in 1997 as one of the six main greenhouse gases that causes global warming along with carbon dioxide (CO2), nitrous oxide (NO2), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).
Methane is a molecule composed of one carbon atom linked to four hydrogen atoms; when heated and combined with oxygen, it produces carbon dioxide and water vapor. Although the concentration of methane in Earth’s atmosphere is small (0.0001% of Earth’s atmosphere), which is only 5% of the total greenhouse gases—less than that of carbon dioxide which accounts for 80%—in terms of greenhouse effects, such as ambient heat propagation, it is considered one of the main causes that accelerate global warming, having a warming impact 84 times that of CO2. According to IPCC’s report on climate change released in August 2021, methane causes global warming by 30% and increases 0.5˚C of the global temperature.
Global Warming Potential [GWP] is a measure of how much each greenhouse gas contributes to the global warming for one hundred years, relative to the emissions of 1 ton of carbon dioxide. Methane is estimated to have a GWP of 28–36, which is 28–36 times greater than that of carbon dioxide.
Source of Methane
Major natural sources of methane include emissions from wetlands and oceans, and from the natural factors resulting from decomposition of organic matter, such as digestive processes of termites. Sources related to human activities include farming, raising cattle, landfills, and burning fossil fuels.
The concentration of methane in the atmosphere has increased about 150% since 1745. Methane is major natural gas mainly used for heating and cooking at home. As it was used to replace coal or petroleum, its atmospheric concentration increased rapidly. Moreover, an unprecedented increase of meat consumption is also contributing significantly. When permafrost begins to melt due to global warming, methane hydrate which is solid methane trapped in it is vaporized, emitting massive amount of methane gas into the atmosphere. This has been happening in Siberia. In 2019, scientists discovered sea boiling due to the emission of methane hydrate in Siberia. Some insist that more than 50% of organic carbon is stored as hydrates in permafrost and on the seabed, and if we fail to stop these emissions, Earth’s environment will be irreversible.
Global Methane Pledge
The Global Methane Pledge is an initiative of the global society to reduce global methane emissions, which is one of the six main greenhouses defined by Kyoto Protocol (Carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride). This is for the global society to search for cooperation plans to reduce global methane emissions at least 30% from 2020 levels by 2030; its target is methane, not comprehensive greenhouse gases. If the goal is achieved, it can reduce warming by at least 0.2˚C by 2050.
Methane stays in the atmosphere for about a decade and breaks down much more quickly than CO2 which can last up to 200 years. That is why it was concluded that reducing massive amount of methane emissions will easily achieve the Paris Agreement’ goal 2015: Holding the increase in the global average temperature rise to well below 2˚C above pre-industrial levels, and pursuing efforts to limit warming to 1.5˚C.
For this, the international society paid attention to the importance of reducing methane emissions in combating global warming, and searched for cooperation plans. The U.S. and EU launched the plan for achieving the Global Methane Pledge in September 2021, and asked key stake-holders to support the pledge. The Global Methane Pledge was launched at COP26 on November 2, 2021. The Republic of Korea too announced to join the pledge and to actively participate in reducing methane emissions; but the world’s top three emitters of methane—China, Russia, and India—did not participate in the pledge.
How to Reduce Methane Emissions
A global methane assessment released in May 2021 by the Climate and Clean Air Coalition [CCAC] and the United Nations Environment Programme [UNEP] showed that human-caused methane emissions can be reduced by up to 45% this decade. Such reductions would avoid nearly 0.3°C of global warming.
The assessment, for the first time, integrates the climate and air pollution costs and benefits from methane mitigation. Because methane is a key ingredient in the formation of ground-level ozone (smog), a powerful climate forcer and dangerous air pollutant, a 45% reduction would prevent 260, 000 premature deaths, 775, 000 asthma-related hospital visits, 73 billion hours of lost labor from extreme heat, and 25 million tonnes of crop losses annually.
We must take immediate action to reduce methane emissions. Human-caused methane emissions are increasing faster than ever since 1980s when the measurement began. Due to the pandemic, the emission of carbon dioxide was reduced rapidly in 2020, but atmospheric methane levels surged by a record-breaking amount.
Agriculture accounts for an estimated 40% of human-caused methane emissions. Cattle and other ruminants’ emissions, via intestinal fermentation, account for roughly 32%. 60 kilograms of greenhouse gas emission is generated to produce one kilogram of beef. Population growth, economic development, and urban migration have stimulated unprecedented demand for animal protein, and the worldwide meat production has quadrupled since 1961. Paddy rice cultivation—in which flooded fields prevent oxygen from penetrating the soil, creating ideal conditions for methane-emitting bacteria—accounts for another 8% of human-linked emissions. Reduction strategies include preventing the burning of fields after harvests, adjusting feed for livestock, regularly draining rice paddies, avoiding meat consumption and having plant-based diet.
Fossil fuels make up about 35% of emissions and have the most potential for reductions. Almost all measures could be implemented at low costs. These include improving the repair of methane leaks at oil and gas facilities and reclaiming abandoned coal mines that leak the gas.
Waste accounts for 20% of methane emissions. When organic material in landfills and in wastewater decomposes, it releases methane. Mitigation strategies include reducing waste that ends up in landfills by recycling and composting. Capturing landfill methane gas and using it as fuel can also lead to economic profit.
Global Effort to Reduce Methane Emissions
Most countries have not included methane mitigation in their pledges under the Paris accord. As awareness of the issue grows, more restrictions on methane are being put in place.
Countries around the world have implemented a variety of policies to reduce methane emissions such as setting industry-specific standards, requiring companies to report their emissions, and taxing emissions. In its most recent five-year plan, China—the world’s top methane emitter—mentioned cutting methane emissions for the first time. In September 2020, the European Commission adopted a methane strategy, signaling potential for new emission policies across the European Union.
Meanwhile, the United States has shown a renewed interest in this issue. President Donald Trump’s administration rolled back landmark regulations imposed under President Barack Obama, but some in Congress are working to restore them. Joe Biden administration has said it would work to “reduce non-CO2 greenhouse gases, including methane.” Still, Korea who aims to halve total emissions by 2030, did not specifically name methane emissions.
The United States called for reductions in methane by holding Leaders Summit on Climate on April 22, 2021.
President of Russia Vladimir Putin called for global action on methane, saying, “We must take into account absolutely every cause of global warming.” And he added, “It would be extremely important to develop broad and effective international cooperation in the calculation and monitoring of all polluting emissions into the atmosphere.” President of France Emmanuel Macron said, “It is important for all of us to start the fight to reduce methane emissions.” President of Argentina Alberto Fernández too stressed a plan to reduce methane emissions. President of Vietnam Nguyen Xuan Phuc said that Vietnam plans to reduce methane emissions from agriculture by 10% by 2030.
Energy ministries from the U.S., Canada, Norway, Qatar, and Saudi Arabia—which represent 40% of global oil and gas production—formed the Net Zero Producers Forum, a cooperative forum that would develop pragmatic net-zero emission strategies, including methane abatement.
Companies, including many oil and gas giants, have also made pledges regarding methane, although some analysts are skeptical they will follow through. “We have to make sure it actually happens,” says Steven Hamburg, chief scientist at Environmental Defense Fund.
