Methodologies

Existing approaches

Under Article 4 of the UNFCCC, Parties to the convention are responsible for reporting anthropogenic greenhouse gas emissions and sinks. Developed countries report through annual National Inventory Reports (NIR), while developing (non-Annex I) countries submit less frequent and detailed National Communications (NC). These reports are based on guidelines developed by the IPCC Task Force on National GHG Inventories (IPCC TFI) and typically involve the  “bottom-up” approach, which combines emission factors with activity data. However, this approach has some drawbacks:

  • Time-consuming, requiring significant effort to gather statistical data.
  • Estimates emissions within a specified domain, which may include only specific political boundaries.
  • May be prone to errors due to uncertain and incomplete data, or mistakes.
  • Relies entirely on self-reporting, which can challenge the goals of transparent, accurate, complete, consistent and comparable (TACCC) reporting.
  • Reports are quality assured through third-party reviews, which only check consistency with guidelines, not the accuracy of the forecast. 

Transitioning to ETF 

Text outlining the requirements and contents of biennial transparency reports under the Enhanced Transparency Framework of the Paris Agreement.

As the UNFCCC process advances, Parties are now encouraged to implement the Enhanced Transparency Framework (ETF) for timely reporting under the ETF. Achieving universal participation in the ETF requires collaboration between Parties and stakeholders to raise awareness of transparency, mobilize resources for ETF implementation and gain political support for transparency’s role in the Paris Agreement.3  This transition involves establishing new reporting and review systems and additional tools for data management. Full operationalization of the ETF will require adequate financial resources and qualified experts.

IG3IS Approach

Offers a solution-based approach tailored to the needs and capabilities of different countries. 

Flowchart illustrating solutions for targeted emission mitigation: urban inventory and flux models, direct observational methods, and data assimilation systems, depicted with increasing complexity.
Figure 1 Different levels of solutions by IG3IS approach

The approach is tiered as shown in Figure 2, with varying levels of measurement and modelling sophistication. Some countries may require only rough estimate of emissions and trends, which can be provided at a lower tier. Others may need more accurate data, including sector-specific emissions, requiring a higher tier.  

Chart showing a multi-tier model complexity approach, ranging from single station monitoring (Tier 1) to tailored, high-resolution modeling with local experts (Tier 3).
Figure 2 Tiers of sophistication of the measurement network and modelling infrastructure and questions that can be addressed for a given combination.
WMO

How does IG3IS work? 

Flowchart illustrating steps for atmospheric GHG concentration analysis: measuring, using sensors, modeling, combining data, focusing on use cases, and benchmarking performance.
  • It uses observation-based approaches to track CO2, CH4, and other GHGs by directly measuring atmospheric concentrations.
  • It uses ground-based, airborne, and space-based sensors with high spatial and temporal resolution for measurements.
  • Measurements are processed with atmospheric inverse modelling systems or other analysis tools to generate top-down estimates of GHG fluxes between the surface and atmosphere.
  • The inverse modelling system incorporates atmospheric transport from state-of-the-art meteorological models with an inverse algorithm that optimizes the GHG fluxes needed to reproduce the observed distribution of each GHG in the presence of the modelled wind field.  
  • Takes a unified approach that combines and analyses atmospheric concentration measurements together with socioeconomic data and information on natural fluxes to better quantify and attribute greenhouse gas emissions and sinks as well as their trends.
  • Focuses on existing-use cases where IG3IS information can meet the expressed (or previously unrecognized) needs of decision-makers, their documentation through “good practice” guidelines for different application areas, and the initiation of new projects and demonstrations that propagate and advance these good practices.
  • The additional observations created through IG3IS pilot projects and approaches to model benchmarking and performance evaluation would feed into the global systems to improve their overall performance.  

Benefits of observation-based emission estimates

  • Observation-based estimates of GHG emissions and removals
  • Provide a critical new data source for tracking GHG emissions, removals and trends complementing bottom-up GHG inventories in the context of climate policies.
  • Offer a comprehensive source of information detailing the spatial, temporal and sectoral distribution of emissions and removals, with improved timeliness to support tracking emission reduction efforts.
  • Account to both anthropogenic and natural emissions and removals.
  • Can be scaled and consistently applied from facility to national levels.  
  • Tailored information products guide emission reduction actions and quantify their impact for users and stakeholders.  
  • Offer clear, updated insights to help stakeholders understand emissions dynamics and refine their strategies to maximise the effectiveness of environmental impact reduction.