Methane emissions. A gas 30 times warmer than CO2, have been greatly underestimated.
Methane is a powerful greenhouse gas. Knowing where emissions are coming from and what are their origins could help effectively limit global warming. It is less publicized than CO2. However, methane (CH4) is a particularly powerful greenhouse gas. According to the latest report from the Intergovernmental Panel on Climate Change, its global warming power at 100 years is around 30 times that of CO2. Since 1750, the amount of methane present in our atmosphere has increased by about 150%. And in total, methane is considered to be responsible for about a third of the current greenhouse effect. Scientists know that part of this methane is of natural origin. The other comes from human activities. However, it is not so simple to distinguish them. And today, researchers at the University of Rochester (United States) say that their predecessors have largely underestimated the amount of methane released to the atmosphere due to the use of fossil fuels. You should know that methane can be divided into two categories. The so-called fossil methane has been sequestered for millions of years in hydrocarbon deposits. It can ooze naturally or be emitted by the extraction and use of fossil fuels. You should know that methane can be divided into two categories. The so-called fossil methane has been sequestered for millions of years in hydrocarbon deposits. It can naturally ooze or be emitted by the extraction and use of fossil fuels, gas, petroleum or coal. The so-called biological methane can be released naturally from sources such as wetlands or via anthropogenic sources such as landfills, rice fields or livestock. These two main types of methane can be distinguished by their isotopic signature. The former no longer contains carbon-14 while the latter still contains carbon-14.
In the atmosphere, more anthropogenic methane than expected
Researchers at the University of Rochester have focused on the issue of fossil methane. To distinguish methane of natural origin from that of anthropogenic origin, they studied air bubbles contained in ice cores extracted from Greenland. Objective: to establish the composition of this air, from the beginning of the XVII century, that is to say before the start of the industrial revolution, to the present day. As humans only started to consume massive amounts of fossil fuels from the middle of the 19th century, the methane present before, in the samples, corresponds to natural emissions. Carbon 14 measurements show that this methane is, until 1870, almost entirely, of biological origin and not fossil. Enough to conclude that the levels of naturally released fossil methane are about ten times lower than previous work had imagined. This would ultimately bring the anthropogenic fossil component from 25 to 40% more than what the experts thought. A result that researchers want to take on the bright side. "If a larger share of methane in our atmosphere comes from human activities, this means that a reduction in emissions can have a real impact in limiting global warming", explains Bejamin Hmiel, the main author of the study and researcher at the University of Rochester.
Millions of hot spots in the Arctic
At the same time, researchers from NASA (United States) were interested in CH4 emissions from the Arctic side. Because in this region, which is warming faster than the rest of the planet, permafrost, this layer of soil, in principle perpetually frozen, has started to thaw. And to release methane, as well as other greenhouse gases, resulting from the putrefaction of organic matter formerly trapped in ice. To understand to what extent this methane could influence global warming, researchers have equipped planes with advanced infrared technology called Airborne Visible Infrared Imaging Spectrometer, Next Generation (Aviris-NG). Then, they flew over 30,000 km2 of the Arctic region. result: they identified two million of what they call hotspots. That is to say, zones with a CH4 excess of 3000 parts per million between their onboard sensor and the ground. The researchers also note that most of these hotspots are concentrated in areas spanning approximately 40 meters around water sources. At more than 300 meters, there are almost no more. Researchers are not explaining this pattern yet. But identifying the factors that lead to it should help clarify the methane emission models in the Arctic and the region's impact on future global warming. And vice versa.
Regards
Totally agree with you than methane emissions have been underestimated.
Hydraulic fracturing releases large amounts of methane (not only accidental leaks ). At all steps of operations (drilling, venting, flaring, production and even after abandoning the well) there are methane emissions.
After stabilizing around in the year 2000s, it started to increase again due to the rapid expansion of hydraulic fracturing, and likely to melting of permafrost and other reasons that you explained. No doubt that watching methane emissions is a must and it is likely that concentrations will rise even faster in the next decades.
Dear Alain,
Thank you very much for your contribution to the discussion. The document is also interesting. The group of researchers who published a study in the journal nature says that we must review upwards the emissions of the human share in the global emissions of methane. The concentration of methane in the atmosphere rose from 722 ppb (parts per billion), during the industrial period, to 1,866 ppb in 2019. This is the highest value in 800,000 years. Methane has long been problematic for scientists because it is difficult to calculate the anthropogenic proportion since there are many natural sources.
Regards
Хотя метан и является более мощным парниковым газом, чем СО2, последнего в атмосфере в двести раз больше. А именно, уровень СО2 составляет 380 ppm (частей на миллион), а метана 1,75 ppm. Поэтому вклад метана в потепление составляет 28% от вклада СО2. Ниже представлен график различных воздействий, влияющих на климат (метан это CH4, непосредственно над CO2).
Это не значит, что можно игнорировать метан – добиваться снижение уровня метана действительно необходимо. Хорошей новостью является тот факт, что с начала 1990-х скорость роста уровня метана замедлилась, а в последние несколько лет рост даже сошел на нет.