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Global Livestock Environmental Assessment Model (GLEAM)

Frequently asked questions

GLEAM overview

What is GLEAM?

The Global Livestock Environmental Assessment Model is a modelling framework developed within the Animal Production and Health Division of FAO. It simulates the functioning and environmental impacts of livestock production activities. The most relevant characteristics of GLEAM are:

  • It is based on Life Cycle Assessment (LCA) methodologies.
  • It runs in a Geographic Information System (GIS) environment.
  • It covers upstream, on-farm and downstream impacts.

The current version of GLEAM (2.0) focuses on the quantification of greenhouse gas emissions related to livestock sector supply chains. Future versions of GLEAM,currently under development, will also include other environmental impacts such as nutrient and water use or interactions with biodiversity.

Why was GLEAM developed?

GLEAM responds and provides solutions to two pressing issues in livestock sustainability:

  • Diagnose. GLEAM captures and provides detailed information on the environmental impacts of each stage of livestock production, allowing an identification of key areas for improvement.
  • Intervention. The model can assess the outcome of different mitigation and adaptation scenarios at local, national, regional or global scale, supporting the stakeholders in the decision-making process towards a more sustainable livestock sector.

What type of information does GLEAM provide?

The outputs of current version of GLEAM include:

  • Livestock numbers and distribution
  • Production and management data on manure
  • Animal feed rations (composition and quality)
  • Livestock commodities production
  • Greenhouse gas emissions from each stage of production and emission intensities by commodity

GLEAM produces the outputs in both aggregated totals and GIS format.

Who are the main receptors of GLEAM outputs?

The transition towards a more sustainable livestock sector is key to ensure future food security and the livelihood of a vast numbers of people. GLEAM supports this transition by providing detailed, evidence-based information on environmental impacts to inform key stakeholders within the sector, including producers, policymakers, private sector organizations, academia, standard setting bodies and non-governmental organizations.

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Results of GLEAM 2.0 - Assessment of greenhouse gas emissions and mitigation potential

What is the global impact of livestock supply chains on climate?

Total GHG emissions from livestock supply chains are estimated at 8.1 gigatonnes CO2-eq per annum for the 2010 reference period. That amount represents 15.6 percent of all human-induced emissions, estimated at 52 gigatonnes CO2-eq for the year 2004 (IPCC, 2014).

What are the most important GHG emissions within the sector?

Methane is the most important gas emitted along livestock supply chains, representing about 50 percent of sector's total (or 4.0 gigatonnes CO2-eq). The remaining part is almost equally share between N2O with 24 percent (1.9 gigatonnes CO2-eq) and CO2 with 26 percent (2.1 gigatonnes CO2-eq).

What are the main sources of emissions?

Emissions from enteric fermentation account for about 44 percent of sector emissions. The production, processing and transport of feed is the second largest source of emissions, contributing about 41 percent of total emissions. Manure management is responsible for about 10 percent of the total, while emissions associated with on-farm and post-farm energy consumption (excluding those related to feed production and fertilizer manufacturing) contribute about 5 percent of total sector emissions.

Which is the scope for mitigation?

It is estimated that sector's emissions could be reduced by approximately 35 percent (about 2.7 gigatonnes CO2-eq). That figure arises from a scenario that calls for all producers in a given system, region and agro-ecological zone were to apply the practices of the 10 percent most efficient producers for that same system, region and agro-ecological zone while maintaining the overall production output.

What are the main mitigation strategies?

Among other measures, GHG emissions mitigation can be achieved through improving current technologies and adopting more efficient practices in feeding, husbandry management and manure management. GLEAM does not analyse scenarios with reduction in consumption.

Can mitigation measures threaten livestock producer's livelihood?

Most of the technologies and practices that mitigate emissions also improve productivity and performance of the herds. Thus, mitigation measures can go along policies for strengthening food security and rural poverty alleviation.

Implications and future steps

What are the implications of GLEAM 2.0 results for the livestock sector?

The results of GLEAM 2.0 highlights the global significance of livestock production in the context of climate change and its mitigation. Livestock sector activities contribute significantly to the global emissions of human-induced greenhouse gases. At the same time, the model shows important mitigation potential across all regions, species and production systems by using technologies and practices already available.

What are the main policy approaches for livestock sector GHG emissions mitigation?

Similarly to most environmental management and development issues, main policy options are extension and agricultural support services, research and development, financial incentives, regulatory options, market friction instruments and advocacy for public awareness.

What is the future of GLEAM?

The future versions of GLEAM will include the following main changes:

  • Updated livestock numbers, distribution maps and revised herd parameters.
  • Inclusion of modules on carbon sequestration, nutrient and water use and interactions with biodiversity.
  • Updated data on feed and inclusion of seasonality for the estimation of feed rations.
  • Inclusion of procedures for the estimation of the impact of feed quality on animal performances.