Invited review: A position on the Global Livestock Environmental Assessment Model (GLEAM)

Area of Science:

• Environmental Science
• Agricultural Science
• Climate Change Modeling

Background:

• The livestock sector significantly impacts global food supply and economic development, but also resource consumption and environmental alteration.
• Accurate assessment of the livestock supply chain's environmental footprint is crucial for sustainable agricultural practices.

Purpose of the Study:

• To review the Global Livestock Environmental Assessment Model (GLEAM), detailing its architecture, methods, and analytical capabilities.
• To explain how GLEAM quantifies greenhouse gas emissions from major livestock commodities.

Main Methods:

• GLEAM utilizes a modular structure (Herd, Manure, Feed, System, Allocation Modules) for comprehensive analysis.
• The model processes inputs and outputs as raster datasets with a 0.05 decimal degree spatial resolution.
• It incorporates spatial data on livestock distribution and crop yields to derive localized feed rations.

Main Results:

• GLEAM v1.0 focuses on quantifying greenhouse gas emissions from 11 primary livestock commodities.
• The model's herd module allows for disaggregation of livestock statistics and captures variations in performance and management.
• Spatial data integration enables the derivation of feed rations reflecting local resource availability, particularly in developing countries.

Conclusions:

• GLEAM provides a robust framework for assessing the environmental impact of livestock production.
• Future development priorities include enhancing data quality, emissions calculation methods, expanding environmental impact scope, and predictive modeling capabilities.