Evaluating the 2019 IPCC refinement for estimating methane conversion factors in Canada.

Area of Science:

• Environmental Science
• Agricultural Science
• Climate Science

Background:

• Methane emissions from liquid manure management represent a significant greenhouse gas source in Canada.
• Existing methane conversion factors (MCFs) do not adequately account for Canada's diverse regional climates and farm management practices.

Purpose of the Study:

• To explore the impact of the 2019 IPCC Refinement methodology on MCF estimates across Canada.
• To assess the influence of regional climate variations and manure management practices on MCFs.

Main Methods:

• Calculated MCFs for 3403 Canadian locations using historical weather data and varied management parameters (emptying efficiency, timing, frequency).
• Evaluated model sensitivity to minimum manure temperature and damping factor.

Main Results:

• Average MCFs varied significantly by ecozone, from 0.15 (Taiga) to 0.27 (Mixedwood Plains), with substantial intra-ecozone variation.
• Improved manure removal frequency and efficiency critically reduced MCFs.
• Manure removal efficiency was highly influential, with MCFs increasing from 0.14 (100% efficiency) to 0.30 (50% efficiency) for triannual removal.

Conclusions:

• The 2019 IPCC Refinement methodology enhances the regional representation of methane emissions from liquid manure compared to the 2006 IPCC guidelines.
• Accurate MCFs require accounting for site-specific climate and management practices, improving national greenhouse gas inventory accuracy.