When we talk about greenhouse gases, we immediately think of carbon dioxide, the main cause of global warming and on which the focus has been placed in all actions aimed at mitigating climate change. However, in recent years scientists have started to sound the alarm about methane . This gas has a much lower persistence than CO2 in the atmosphere – about a decade versus centuries – but, in turn, it is capable of absorbing much more energy.
In June 2019, a work published in the journal Science already warned that the increase in methane concentrations in the atmosphere endangers the fulfillment of the objectives established in the Country Agreement to limit the temperature increase to 1.5 -2 ° C above pre-industrial levels. This work showed how methane emissions have skyrocketed in recent years: specifically, its concentration in the atmosphere in the period between 2014-2018 almost doubled the rate observed since 2007.
Now, a preliminary estimate published in a report by the US National Oceanic and Atmospheric Administration (NOAA) confirms this trend: atmospheric methane levels have reached a new all-time high. To perform the calculations, scientists at NOAA’s Terrestrial System Research Laboratory have been collecting methane samples since 1983 at a network of sampling points distributed throughout the planet. Although the final calculations for 2019 will not be available until the end of this year, the authors already warn that the upward trend is very clear. Specifically, and according to preliminary data, the global methane concentration in December 2018 was 1866 parts per billion (ppb), and in 2019 this figure was 1874.7 ppb.
Origin of methane in the atmosphere
The problem with methane is that its emissions are very difficult to control. Among the natural sources, for example, the microbial activity of wetlands stands out , something about which little can be done. Permafrost, a permanently frozen layer of frozen subsoil, stores large amounts of this gas. Its thawing, which is accelerating dangerously as a result of global warming, has consequences of a very diverse nature, including the release of methane.
Regarding human activities, various studies have shown in recent years that the high increases in methane concentrations in the atmosphere are largely due to agriculture and livestock : organic matter that rots in rice fields, methane generated in the digestive system of animals, stored in large quantities of manure, etc. Although the focus has been placed on meat, and certainly reducing its consumption in Western countries would have many benefits for both health and the environment, it is also a complicated matter since in other areas of the globe it is it would compromise the food security of thousands of people.
For many experts, the ultimate solution to the methane problem is the same as for carbon dioxide: limiting its release at oil and gas extraction sites, which are also one of the main anthropogenic sources of methane. Natural gas, in particular, consists primarily of methane, and is highly prone to leakage from extraction wells.
In May 2019, a paper published in the journal Nature Sustainability proposed a counterintuitive solution: trapping methane from the atmosphere and converting it to carbon dioxide using zeolites, a type of porous material. The idea is that, as methane has much more capacity to trap heat than carbon dioxide, at least in the medium term a sixth of global warming would be suppressed and time would be bought , something not inconsiderable in the race against time to face the climate emergency.
