5. Wetlands: A Major Natural Source Responsible for Methane Emission

Methane (CH₄), an important greenhouse gas (GHG), contributes ~33.0% to the total global GHGs emissions and accounts for 15–20% to the global warming. As the second most important human-generated GHG after CO_2, CH₄ is strongly linked with various climate phenomena. Most of the wetlands from tropics to temperate have been reported to have significantly enhanced emissions of CH₄ during recent years. In wetland, microbial communities are a major determining factor in controlling the carbon cycle. The terrestrial wetlands are also among the key CH₄ emitters and play a major role to climate change. The role of wetland expansion in CH₄ emissions and its consequences on climate change and global warming might be a major concern for the future world. The methanogens and methanotrophs, two physiologically different microbial communities, seem to be crucial for future research investigations while comparing the CH₄ production and consumption in wetland ecosystems. Anthropogenic disturbances related to wetlands are likely to influence the altering of microbial community composition of methanogens and methanotrophs and consequently net CH₄ flux. The terrestrial wetlands have been reported to act as a source and sink for atmospheric CH₄. Therefore, recent concerns about CH₄ emission from terrestrial wetlands could be addressed properly because it is one of the major causes in contributing the status of CH₄ in the environment.