The amount of gas has remained unknown
The research team combined ground-based and satellite (TROPOMI) measurement techniques to quantify the amount of gas released to the atmosphere by Lusi. Both techniques indicated a total methane output of about 100,000 tonnes per year. This is the highest methane emission ever recorded experimentally for a single natural gas manifestation.
The results, published recently in Scientific Reports, suggest that recent estimates of global geological methane emissions, based on radiocarbon in pre-industrial era ice cores (ranging from 100,000 to 5,400,000 tonnes of CH4per year), may be underestimated.
In other words, the amount of methane released by Lusi alone, already matches the minimum assessment of the ice-core based studies for the entire planet.
Estimates for terrestrial natural gas emissions
The emissions from Lusi are thought to be proportionally consistent with the level of methane flux (the so-called “emission factor”) typically released by other, similar terrestrial natural gas manifestations (e.g. mud volcanoes, large methane seep systems).
If all these degassing sites are combined globally, the bottom-up global estimates lead to a total output in the order of 40-50 million tonnes per year.
Knowing the true amounts and fluxes of methane release from natural geological sources is important to better assess the anthropogenic gas emissions, such as from the oil industry, and the atmospheric methane budget in general.
This new study also suggests that satellite-derived gas emission measurements can be a key tool to support ground-based studies and improve global geo-methane budget estimates.