Methane, it is now well known, is a potent greenhouse gas. However, as for CO2The amount of this gas has increased since 2006.AtmosphereAtmosphere worldly. But when CO originated2 is primarily human and is related to combustioncombustion of fossil fuels, these new emissionsemissions Methane appears to be mainly related to biological processes.
convinced? Not necessary. Because if it is normal to observe methane emissions of natural origin, the acceleration we have seen over the past two decades is worrying and says a lot about the stage of climate change we have reached.
Higher emission rates than during peak industrial production
because it is a phenomenon that has already been observed in the past at particularly critical moments in climate history teretere, This acceleration of methane emissions is in fact of the same magnitude as that observed at the transition between ice agesice ages and interglacial (we speak of the end of glaciation). So we would currently be in this phase of climate change, towards a much warmer period than what we know today.
Before the industrial revolution and the beginning of large-scale consumption of fossil fuels, the amount of methane was about 0.7 ppmppm (parts per million) in the atmosphere. It is now 1.9 ppm or 2.7 times higher and continues to rise. Of course, atmospheric methane levels increased rapidly with the onset of industrialization in the 19th century.I century, but had leveled off by the late 1990s, suggesting that a balance had finally been reached between human-induced production and methane sinks. However, things suddenly changed in 2006. Then the emissions started up again with even greater intensity, without anyone understanding exactly why. Since the beginning of 2020, emissions rates have exceeded those reached during the peak of industrial production in the 1980s! This development has been inserted lightslights In a new study published in the journal global biogeochemical cycles,
An uncontrolled climate that increases natural methane emissions
If more than half of the methane emissions are from the combustion of OilOil, livestock, waste storage and combustion, the rest comes from natural sources and from plant decomposition, especially in tropical and northern wetlands. And it is indeed from this latter part that most new emissions appear to be coming, as recent studies have shown. Methane emissions are certainly of natural origin, but are directly linked to global warming. Because the increase in global temperature means that if dry areas are drying up faster, then humid areas are undergoing an increase in intensity. precipitationprecipitation, HeatHeat And the humidity thus boosts the production of plants, which produce even more methane when they decompose. Add to this the development of intensive livestock farming and the rapid expansion of megacities that generate enormous amounts of waste, and you have an explanation for an unprecedented acceleration in human history of methane emissions.
Signs that usually testify to the end of the glaciation
This evolution is also comparable to that seen 12,000 years ago, which was marked by a dramatic warming of Greenland. In fact, in just a few decades the temperature would have increased by about 10°C, causing a major ecological upheaval.
This sudden climate development is usually seen at the end of an ice age. The whole climate system is then ruthlessly reorganized: melting ice caps, changes in ocean currents, expansion of tropical regions… many signs that we can see in the present day. So we may be experiencing a new ending, and not the one frozen in time. break from past events porteporte Definitely human imprint.
While CO2 emissions are still in the limelight, researchers are now turning our attention green house gasgreen house gas : methane (CH4). They warn that global emissions of this extremely potent greenhouse gas have increased by about 10% over the past 20 years. And here it is present in record concentrations in our atmosphere.
article of Nathalie MeyerNathalie Meyer Published on July 21, 2020
greenhouse gases, of course carbon dioxidecarbon dioxidefamous CO2, But it also has less media methane or CH4, Although less abundant, it is far more potent than CO.2, Over a period of 20 years, the warming power of KilogramKilogram The amount of methane is about 85 times that of one kilogram of CO.2, Over a period of 100 years, the heating power of methane is always at least 28 times greater than that of CO.2,
And, a blow to the fight against global warming, the latest updates global methane budget an initiative of global carbon projectAn international research program aimed at providing an accurate picture of the global carbon cycle – today revealed that methane emissions reached 600 million tonnes in 2017 – the latest year for which data is available. Available – of which over 360 are man-made.
This is 50 million tonnes – of which 40 are of anthropogenic origin – and is 9% higher than the 2000–2006 average. United States Agency for Oceanic and Atmospheric Observations (NOAANOAA) reported, for its part, an atmospheric concentration of 1,875 parts per billion (ppb) in 2019; ie 2.5 times the pre-industrial concentration!
Specifically, emissions from anthropogenic sources. l’AgricultureAgriculture and waste contributed 60% of this increase and fuelfuel The remaining 40% fossils. The largest increases in methane emissions were recorded in three major regions: Africa and the Middle East, China and South Asia, and Oceania. Europe, on the other hand, registered a slight decline in its emissions. A difference that inevitably falls on emissions from the agriculture sector.
It’s not too late to reverse the trend
To reach these conclusions, the researchers relied on several approaches. The first is called the ascendant. It takes into account the declarations of countries that make an inventory of greenhouse gas emissions of human origin (fossil fuels, agriculture, landfills, etc.). For example, it adds them to natural emissions calculated using simulations of wetlands or wildfires.
The second approach is from the top down. It starts with global methane concentrations and uses models to trace their origins. None of these methods is perfect. They are complementary. According to the researchers, the top-down approach gives more reliable estimates overall, but the bottom-up approach makes it possible to work on more specific areas.
Last but not least: The researchers found no evidence of a possible increase in emissions from the Arctic region. something that surprised the experts, who expect SourceSource The ice, to release the amount of methane trapped in the frozen ground, triggers what they call a positive feedback: the release of greenhouse gases that increase warming as temperatures rise. A clue that suggests that the Earth system has not yet reached this point of no return. And there’s still time to take corrective action.