A Global Methane Observation System to Reduce Uncertainty for Anthropogenic and Natural Sources and Sinks for...

Area of Science:

• Earth and Environmental Sciences
• Atmospheric Science
• Climate Science

Background:

• Atmospheric methane (CH4) concentrations are increasing, contributing to global warming.
• Current methane observing systems are insufficient for detecting emission trends, especially in remote areas.

Purpose of the Study:

• To present a framework for a global ecosystem-methane observing system.
• To reduce uncertainties in methane emissions, differentiate between natural and anthropogenic sources, and enable trend detection for mitigation verification and early warning of climate feedbacks.

Main Methods:

• Utilized bottom-up inventories and process-model ensembles from 2014-2023.
• Proposed a framework incorporating high-resolution satellite constellations, expanded flux networks, wetland mapping, and denser ground-based atmospheric column measurements.

Main Results:

• Global anthropogenic methane emissions have an uncertainty of ~32%.
• Natural methane sources (wetlands, fires, inland waters) exhibit higher uncertainties (~70%) with trend uncertainties reaching ~200%.
• Targeted additions of flux towers and in situ instruments in tropical regions could significantly reduce uncertainties.

Conclusions:

• Enhanced methane observation systems are crucial for accurate emission quantification and trend detection.
• Integrating satellite, ground-based, and flux network data is essential for improving methane budget closures.
• Strategic placement of new instruments, particularly in under-sampled regions, can cost-effectively reduce uncertainties and support climate mitigation efforts.