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.