Amazon rainforest. Photo: Graham Hobster
Amazon rainforest generates more methane than initially thought

Amazon rainforest. Photo: Graham Hobster

A study conducted by Brazilian and British researchers, published by Nature, showed that swamped areas in the Amazon rainforest produce between 15 and 20 million tons of methane every year – the equivalent of emissions by all oceans combined. Fossil fuels, for instance, are responsible for producing roughly 167 million tons every year around the world.

During the dry season, vegetation grows considerably over tree branches. When the rainy season begins, part of this vegetation dies and decomposes underwater – a process which releases methane. According to the study, the Amazon is “a region that represents up to one-third of the global wetland CH4 source when trees are combined with other emission sources,” thus having a bigger influence on the atmosphere’s methane concentration than initially thought.

</p> <p>Luana Basso, one of the researchers, says that the study will contribute to measuring how much <a href="">human activity</a> contributes to these kinds of methane emissions. Hydroelectric dams, for instance, create artificially swamped areas &#8211; with large submerged forests that also release methane.</p> <p>Methane molecules have the capacity to retain 21 times as much heat as carbon dioxide (CO<sub>2</sub>), and are among the biggest greenhouse effect agents. A 2008 study published by the European Project for Ice Coring in Antarctica shows that methane concentration levels today are 2.5 times higher than at any point over the last 800,000 years.</p> <p>Human activity remains the leading cause for the release of methane into the atmosphere, whether it’s through the use of fossil fuels, the decomposition of human waste and sewage, or cattle ranching. In 2016, Brazil alone had 198 million cows – a number just shy of the country&#8217;s total human population.</p> <h3>How the study was carried out</h3> <p>Back in 2011, researchers flew over Amazon areas in the states of Pará, Acre, Amazonas and Mato Grosso. They collected samples of air in glass bottles and later analyzed them to discover the concentration of gases that cause the greenhouse effect (notably carbon dioxide, methane, and carbon monoxide). These measurements served as a basis for their estimates on how much of these gases are released.</p> <p>Between 2013 and 2014, another team of researchers started measuring methane released by trees – as well as gases which come from underwater. Samples were collected in 13 spots in the Amazon, in streams and tributary rivers to the Negro, Solimões, Amazonas and Tapajós – some of the rainforest’s biggest rivers. The researchers used floating chambers to measure methane emissions on the water&#8217;s surface. Meanwhile, fixed chambers were used to measure the methane levels released by 2,300 trees.</p> <p>The data was used to estimate how much methane the forest releases as a whole. And the results from both the water and trees were very similar.

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MoneyDec 28, 2017

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