One carbon atom and four hydrogen atoms are the only ingredients needed in a recipe for climate change acceleration. Bind them together, and you have methane (CH4), and extra methane in the atmosphere turbocharges global warming. Annual emissions of methane steadily increased between 1985 and 2000 and then leveled off. But seven years later they started rising again and the reasons for this rise are not fully understood, as reported by Jonathan Mingle in his recent Wired article. What is understood is this added methane may power the globe past the 2 degrees Celsius temperature rise targeted in the Paris Agreement.
Methane comes from a variety of natural and human sources, but human activity accounts for 60% of the methane released into the atmosphere each year, with the three largest contributors being fossil fuel production/transmission, agriculture, and waste. The remaining 40% is from natural sources, with the majority coming from the world’s wetlands. But don’t go looking for it, because methane is a colorless, odorless gas in its natural state
The good news is that methane sinks take up about 96 percent of the annual methane. These sinks are primarily chemical reactions in the atmosphere and soil. The bad news is that the remaining methane turbocharges global warming.
Methane a super warmer
Scientists measure the warming potential of various greenhouse gases by comparing them to carbon dioxide (CO2) using a measure called CO2-eq (CO2 equivalent). For example, if actual atmospheric CO2 levels are 410 ppm, but the CO2-eq level is 500 ppm, we then interpret the data to show that the warming potential of all gases other than CO2 is equal to a 90 ppm increase in CO2 levels.
The effect of particular greenhouse gases on global warming is a function of two factors: warming potential and lifetime (time in the atmosphere). Methane’s lifetime is short (~12 years) compared to CO2, which lasts for centuries, but methane’s warming potential is up to 87 times greater than CO2. Over 20 years, a ton of methane has a warming potential of 84-87 tons of CO2. So, a little methane goes a long way.
The mystery of increasing methane
Various studies speculate on potential causes for increased methane emissions. Reports from the NASA Earth Observatory attribute the rise to fossil fuels, agriculture, and wetlands. However, this analysis is unsatisfactory since we already know that these are the three largest sources. More work is needed in tracing these unaccounted-for emissions, but two possibilities seem to be good candidates for sourcing extra methane.
Wetlands stand a good chance of being the culprit. We already know that they are a significant methane contributor, and perhaps warmer global temperatures increase metabolic rates in microbial organisms due to warmer environments. It is also worth considering that temperatures in the far north and Arctic have soared, rising faster than the global average. Permafrost melt and the drying of boreal peatlands expose vast amounts of partially decomposed soils to bacterial consumption, so higher metabolic activity combined with new sources of food and nutrients may be behind the mystery.
A second, reasonable explanation is increasing methane release from the extraction of fossil fuels. A 2020 article in the Carbon Brief (Robert McSweeney) summarizes research indicating we severely underestimate how much methane is attributable to this source.
Methane loss from wells that extract natural gas (CH4) and pipeline losses during
Reporting in 2020 from the New York Times documented significant CH4 leaks at multiple facilities in the Permian Basin, where oil and gas extraction is the primary industry. Also, in 2018, a methane leak from a blowout at an Exxon Mobil drilling site in Ohio was only detected from space. Satellites detected the methane plume on the 13th day of the blowout, and by then, the methane release rate was approximately 120 metric tones per hour. The blowout lasted 20 days in total. This detected rate was nearly double that of the 2015 SoCalGas leak in Aliso Canyon, California. A colorless and odorless gas is hard to detect, what are the chances that leakage from gas wells is higher than estimated.
Regardless of the source, increasing atmospheric methane turbocharges global warming and poses trouble for efforts to mitigate climate change.
More Methane (Source: ArcheanWeb) – https://archeanweb.com/2020/01/22/more-methane/ Also:
Methane Tracker 2020 (Source: IEA) – https://www.iea.org/reports/methane-tracker-2020 Also:
Atmospheric Methane Levels Are Going Up—And No One Knows Why (By Jonathan Mingle; Wired) – https://www.wired.com/story/atmospheric-methane-levels-are-going-up-and-no-one-knows-why/ Also:
Unexpected Surge in Atmospheric Methane (Source: Climate Nexus) – https://climatenexus.org/climate-change-news/methane-surge/ Also:
Methane emissions from burning fossil fuels has been ‘vastly underestimated,’ study says (By Doyle Rice; USA Today) – https://www.usatoday.com/story/news/nation/2020/02/19/burning-fossil-fuels-emits-more-methane-climate-change-study/4798547002/ Also:
Human-caused emissions of methane from the extraction and use of fossil fuels may have been “severely underestimated”, a new study suggests. (By Robert McSweeney, Carbon Brief) – https://www.carbonbrief.org/methane-emissions-from-fossil-fuels-severely-underestimated Also: