Observation and research progress of modern oceanic methane cycle

Out of concern for global climate change and the demand for energy resources, methane has increasingly become the current focus of human society. A large amount of natural gas hydrate is stored in the ocean, which has many important biochemical reactions related to methane, supports the prosperous chemoautotrophic synthetic biological community on the seabed, effectively regulates the methane flux into the atmosphere, and plays an irreplaceable role in the global carbon cycle. At the same time, methane seepage caused by the dynamic activity of natural gas hydrate is a critical way to transport material and energy from the lithosphere to the outer sphere, which has a far-reaching impact on the marine environment. In this paper, we systematically introduce the geological control factors of modern seabed methane seepage, the consumption of methane by sediments and water columns, the simulation research of marine methane cycle, the methane observation and relevant research results in typical sea areas, and finally points out the development trend of marine methane cycle research. This review comprehensively considers the influence and limitation of environmental, biological and technological factors on the marine methane cycle, examines the temporary achievements and existing problems from the perspective of a geologist, and puts forward our own thinking, hoping to arouse the attention and support of the whole society to the major scientific problems related to methane and subsequent marine observation technology.