by Anshul Dash
NASA has developed a 3-dimensional picture of the Earth with methane concentrations. This picture shows the numerous sources of methane on the ground and its behavior as it moves through the atmosphere. NASA has combined multiple data sets from emissions inventories, including fossil fuel, agricultural, biomass burning and biofuels, and simulations of wetland sources into a high-resolution computer model.
Methane is the second-most influential greenhouse gas after carbon dioxide, responsible for 20-30% of Earth’s rising temperatures. Methane concentrations have more than doubled since the Industrial Revolution, accelerating the increase in global temperatures. Methane is more efficient at trapping heat than carbon dioxide; however, the lifetime of a methane molecule is shorter than that of carbon dioxide, which is why carbon dioxide is still the most prominent contributor to global warming.
In addition to fossil fuel activities, sources of methane also include the ocean, flooded soils in vegetated wetlands along rivers and lakes, agriculture, such as rice cultivation, and the stomachs of ruminant livestock, including cattle. It is estimated that up to 60% of methane emission is the result of human activity. As human populations continue to grow, changes in energy use, agriculture and rice cultivation, livestock raising will influence methane emissions.
NASA’s 3D model can estimate methane emissions based on known processes for certain land-cover types, such as wetlands. The model can also simulate the atmospheric chemistry that breaks down methane and removes it from the air. It also shows that once methane emissions are lofted up into the atmosphere, high-altitude winds can transport it far beyond their sources.
The model shows several locations that stand out. In South America, the Amazon River basin and its adjacent wetlands flood seasonally, creating an oxygen-deprived environment that is a significant source of methane. In India, rice cultivation and livestock are the two driving sources of methane. China’s economic expansion and large population drive the high demand for oil, gas and coal exploration for industry as well as agriculture production, which are its underlying sources of methane.
The modeling of methane concentrations around the globe also helps NASA plan future field and satellite missions. One of the satellites that NASA is planning to launch in 2023 is called GeoCarb. The satellite will provide space-based observations of methane in the atmosphere over much of the western hemisphere.
Overall, with a more detailed understanding of methane concentrations worldwide, the doubts scientists had previously can be cleared by giving a qualitative understanding of how methane moves around the atmosphere and where it’s produced. By predicting where methane will end up in the atmosphere and where its sources are located, scientists can mitigate methane emissions, thus slowing down the effects of climate change.