Methane is the most important anthropogenic greenhouse gas after CO₂ and is responsible for roughly a third of current global warming. Given its relatively short atmospheric lifetime of about a decade, methane is an essential target to slow down global warming on the short term. As such, over 155 countries have signed the Global Methane Pledge to reduce global methane emission by 30% in 2030 compared to 2020.

Over the past few years, we have seen a true revolution in our space-based ability to detect, identify, and quantify emissions from methane hot spots and large point sources (‘super-emitters’) that represent the low-hanging fruit for emission mitigation efforts. Contributing satellites range from flux mappers detecting methane super-emitters at ‘city-scale’ resolution globally every day to satellites that target methane emissions at ‘facility-level’ and include instruments not originally designed to observe methane that do not have operational methane products.

As such, the current space-based methane point source/hot spot observing system consists of a heterogeneous plethora of instruments with widely varying observation characteristics and the system will further expand over the next few years with the launch of new satellites. This makes the overall system complex and difficult to understand for policy users that have a strong need for information on super-emitters to enable mitigation activities and improve reporting of emissions under the UNFCCC Paris Agreement.

Objective

Within the MEDUSA project, we will compare the various satellite products, both from the same instrument using different algorithms and/or produced by different research teams, as well as between different satellites. Where possible, we will validate the emission products such as through controlled releases. We will also develop a framework for methane flux uncertainty for the various types of instruments. In addition, we will perform a few case studies highlighting the potential of these point source/hot spot methane observations. MEDUSA also has a work package on facility-level satellite observations of CO₂, which is an even more recent area of research.

Current satellites in MEDUSA: Sentinel-5P TROPOMI, GHGSat Constellation, EMIT, EnMap, PRISMA, Landsat 8, Sentinel-2, Sentinel-3, and GOES.

Future satellites (TBC): GOSAT-GW, Sentinel-5, MTG, MethaneSAT , Carbon Mapper, …