Cows and rice pad­dies boost meth­ane emis­sions: Study

Kuwait Times - - HEALTH -

Global meth­ane emis­sions from agriculture and other sources have surged in re­cent years, threat­en­ing ef­forts to slow cli­mate change, an in­ter­na­tional study has found. Re­searchers led by French Lab­o­ra­toire des Sci­ences du Cli­mat et de l'En­vi­ron­nement (LSCE) re­ported that meth­ane con­cen­tra­tions in the air be­gan to surge around 2007 and grew pre­cip­i­tously in 2014 and 2015.

In that two-year pe­riod meth­ane con­cen­tra­tions shot up by 10 or more parts per bil­lion (ppb) an­nu­ally, com­pared with an av­er­age an­nual in­crease of only 0.5 ppb dur­ing the early 2000s, ac­cord­ing to the study re­leased by the Global Car­bon Project, which groups cli­mate re­searchers.

Marielle Saunois, lead au­thor of the study and as­sis­tant pro­fes­sor at Univer­site de Ver­sailles Saint Quentin, said that the in­crease in meth­ane emis­sions could threaten ef­forts to limit global warm­ing. "We should do more about meth­ane emis­sions. If we want to stay be­low a 2 de­grees (Cel­sius) tem­per­a­ture in­crease, we should not fol­low this track and need to make a rapid turn­around," she said in a state­ment.

Less preva­lent

Meth­ane is much less preva­lent in the at­mos­phere than car­bon diox­ide (CO2) -- the main man-made green­house gas-but is more po­tent be­cause it traps 28 times more heat. The re­port did not say to what ex­tent meth­ane con­trib­utes to global warm­ing. CO2 emis­sions are ex­pected to re­main flat for the third year in a row in 2016, thanks to falls in China, the Global Car­bon Project said last month. Saunois said that while the rea­sons be­hind the meth­ane surge are not well un­der­stood, the most likely sources are cat­tle ranch­ing and rice farm­ing. Cows ex­pel large quan­ti­ties of meth­ane and the flooded soils of rice pad­dies are homes for mi­crobes that pro­duce the gas. She cited data from the United Na­tions' Food and Agriculture Or­ga­ni­za­tion in­di­cat­ing that live­stock op­er­a­tions world­wide ex­panded from pro­duc­ing 1.3 bil­lion head of cat­tle in 1994 to nearly 1.5 bil­lion in 2014, with a sim­i­lar in­crease in rice cul­ti­va­tion in many Asian coun­tries.

Robert Jackson, a co-au­thor of the pa­per and Pro­fes­sor in Earth Sys­tem Sci­ence at Stan­ford Univer­sity, said that meth­ane can come from many dif­fer­ent sources, in­clud­ing nat­u­ral sources such as marshes and other wet­lands, but about 60 per­cent comes from hu­man ac­tiv­i­ties, no­tably agriculture. A smaller por­tion of the hu­man con­tri­bu­tion, about a third, comes from fos­sil fuel ex­plo­ration, where meth­ane can leak from oil and gas wells dur­ing drilling. "When it comes to meth­ane, there has been a lot of fo­cus on the fos­sil fuel in­dus­try, but we need to look just as hard, if not harder, at agriculture," Jackson said. — Reuters

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