Weekly Current Affairs: April week- 3 - Atmospheric methane concentration at record levels’

Global atmospheric concentration of methane 2019 levels are the highest since record-keeping began in 1983, according to a new preliminary estimate released by the United States National Oceanographic and Atmospheric Administration (NOAA).

Global atmospheric concentration of methane 2019 levels are the highest since record-keeping began in 1983, according to a new preliminary estimate released by the United States National Oceanographic and Atmospheric Administration (NOAA).

About:

• Methane (CH4) is a colorless, odorless, and highly flammable gas composed of one carbon atom and four hydrogen atoms.
• It can be produced naturally and synthetically, and when burned in the presence of oxygen, it produces carbon dioxide and water vapor.
• Methane is the primary component of natural gas and is used to produce heat and electricity around the world.
• Methane is also used in chemical reactions to produce other important gases like hydrogen and carbon monoxide and carbon black, a chemical compound that's found in some types of rubber used in car tires.

Key-highlights:

• Global atmospheric concentration of methane has hit an all-time high — to 1,875 parts per billion (ppb) in 2019 from 1,866 ppb in 2018.
• Not only is the 2019 figure the highest since record-keeping began in 1983, the increase during the year was the second-largest single-year leap in over two decades.
• In a paperpublished in 2019, NOAA scientists found that the increase in methane emissions between 2013 and 2018 was 50 per cent higher than in the previous five-year period. 

Sources of methane:

• There are both natural and human sources of methane emissions.
  • The main natural sources include wetlands, termites and the oceans. Natural sources create 36% of methane emissions.
  • Human sources include landfills and livestock farming
• Cows and other grazing animals host microbes in their stomachs, gut-filling hitchhikers that help them break down and absorb the nutrients from tough grasses. Those microbes produce methane as their waste.
• The manure that cattle and other grazers produce is also a site for microbes to do their business, producing even more methane. 
• Rice paddies are a lot like wetlands: When they’re flooded, they’re filled with calm waters low in oxygen, which are a natural home for methane-producing bacteria.

Why methane is a concern?

• Most potent GHG: Of all the greenhouse gases, methane is one of the most potent because of its ability to efficiently absorb heat in Earth’s atmosphere.
• Long-lasting: Methane lasts for maybe a decade in Earth's atmosphere before it begins to react with a free radical called hydroxyl and turns into carbon dioxide, where it can stay there for centuries.
• Sea level rise: Greenhouse gases like methane heat up the atmosphere, and as much as 90 percent of that excess heatis absorbed by the oceans. This heat causes seawater to expand in volume. This effect, along with glacial melting, causes sea levels to rise.
• Thermal expansion: Scientists have known for a long time that carbon dioxide heats Earth’s atmosphere and oceans, causing them to expand, but they only recently discovered that short-lived greenhouse gases like methane and CFCs (gases that contain chlorine or fluorine) also spur thermal expansion.

Conclusion:

While these preliminary numbers will be subject to further analysis before final estimates are released in November, the sheer magnitude of the increase, as well as the fact that the new data merely highlighted existing trends, is a cause of concern. Such climate ‘feedbacks’ are largely beyond human control and are expected to intensify with increasing temperatures.