The workshop (26-30 September 2022) attracted 1078 registered participants and 203 pre-recorded presentations and posters. Online questions for pre-recorded materials, interactive online poster sessions and specific topic discussion sessions resulted in 81 issues on key technical challenge areas being identified and 126 recommendations being made to address these. The themes covered were metrology in support of the physical science basis of climate change and climate observations as well as its role as an integral component of operational systems to estimate greenhouse gas emissions based on accurate measurements and analyses.

The workshop website provides a long-term record of the event, including numerous pre-recorded presentations and posters that are publicly available. Organized along two major themes, the workshop covered multiple topics.

Theme 1 addressed ‘Metrology in support of the physical science basis of climate change and climate observations’. It covered metrology in understanding our planet's climate, including measurements and monitoring of the climate system using various techniques. This theme also involved propagating uncertainties from measurements to derived products, modelling, reanalyses and Earth system models. It focused on global and regional observations to understand climate trends. Specific topics included:

• Atmospheric chemistry and physics
• Ocean and water chemistry and physics (including hydrology)
• Earth energy balance
• Biosphere monitoring
• Cryosphere monitoring

Theme 2 of the workshop addressed ‘Metrology as an integral component of operational systems to estimate greenhouse gas emissions based on accurate measurements and analyses’. It covered a range of activities related to accurately measuring and analysing greenhouse gas emissions, including targeting, quantifying, and tracking emissions at different scales. The theme also addressed the development of measurement data and tools to mitigate anthropogenic forcing and attribute emissions across various geographic scales. Additionally, it included the measurement of land-use, land-use change, forest fluxes, and urban fluxes. The topics covered within the theme were:

• Accuracy requirements for atmospheric composition measurements across economic sectors, and temporal and spatial scales
• State of play in integrated approaches for advanced greenhouse gas (GHG) emission estimates and the way forward to operational services
• Novel GHG concentration and flux methods and sensors
• Strengthening the linkage of remote sensing GHG concentration measurements to emission fluxes

The workshop was preceded by two events, one in 2010 on Measurement Challenges for Global Observation Systems for Climate Change Monitoring and the second in 2015 on Global to Urban Scale Carbon Measurements.

Follow up on the implementation and progression of the recommendations within the report is being coordinated by a Sector Task Group on Climate Change and Environment of the International Committee of Weights and Measures (CIPM).

Report available here

Atmospheric Inversion Approach discussed in Theme 2: Complex urban centres contain a range of emission and uptake sources (for example buildings, roads, industrial and power generation plants) located throughout. Incoming winds bring GHG’s into the region that mixes with those of the city. Networks of concentration measurement sites provide data that - coupled with numerical weather prediction and dispersion models and use of optimization methods - quantify incoming, outgoing and internally produced greenhouse gas emissions.
Credits: Whetstone, James R.