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Global Livestock Environmental Assessment Model (GLEAM)

In practice

How to use GLEAM in projects

Moving towards a more sustainable livestock sector requires a sound, evidence-based diagnostic of the undesired environmental side effects. Stakeholders can then identify and assess intervention areas and options. GLEAM is a key contributor to both processes. The model offers a detailed picture of the 'current' situation, but also can be used as a scenario assessment tool for different adaptation and mitigation options.

GLEAM has been used in the following projects and case studies, incorporating valuable feedback from experts and from the field.

Regional case studies on climate change mitigation and productivity gains in livestock supply chains

While many attempts have been made to quantify the mitigation potential of single technologies, few systematic studies exists for assessing “best-bet” options in different production system and regions, and their impact on food security. To explore how mitigation could be achieved in practice, GLEAM was used to develop a modelling effort based on six practical case studies in selected regions and livestock production systems, namely: mixed dairy production in South Asia; commercial pig production in East and Southeast Asia; specialized beef production in South America; small ruminant production in West Africa; mixed dairy production in OECD countries; mixed dairy production in East Africa. The baseline production systems characteristics, GHG emissions and production levels were taken from GLEAM 1.0, for the 2005 reference year. Mitigation options were selected according to their a priori mitigation potential, applicability to the respective regions and systems, anticipated economic feasibility and positive implications on productivity and considering potential trade-offs with other environmental concerns. They interested different stages of the supply chains, including improvements in: feed quality, grazing management, preventive health measures, reproduction and breeding strategies, manure management and energy efficiency.

The mitigation potential of each of the selected species, systems and regions ranged from 14 to 41 %. While comparably high mitigation potentials were estimated for ruminant and pig production systems in Asia, Latin America and Africa, large emission reductions can also be attained in dairy systems with already high levels of productivity, in OECD countries. The mitigation potential was assessed for constant final output of products, which allows clear comparison of mitigation effects. However, the modelled interventions can lead to a concomitant reduction in emissions and increase in production, contributing to food security. This is particularly the case for improved feeding practices and better health and herd management practices. Livestock systems also have a significant potential for sequestrating carbon in pasturelands and rangelands trough improved management, as illustrated in two of the six case studies. For more information see: Regional Environmental Change (2016)

Expanding the scope of GLEAM: the impact on biodiversity

The environmental impacts of livestock are not restricted to greenhouse gas (GHG) emissions. The sector is an important user of natural resources (land, water) and contributor to pollution (nutrients, ecotoxic substances). All these pressures have, in turn, an impact on biodiversity which is located at the endpoint of environmental cause-effect relationships. Additional modules are currently being developed to expand the scope of GLEAM to other environmental aspects such as nutrients, water and biodiversity. The biodiversity module uses the detailed information and modelling already available in GLEAM concerning the contribution of livestock to land use and GHG emissions. These contributions are translated into impacts on habitat and climate change – currently the two most important drivers of global biodiversity loss – and ultimately into impacts on wild species. To do this, internationally recognized methods linking land use and climate change to losses in species richness and abundance were adapted to the context of livestock production. The biodiversity module is in the finalization phase and will provide a first assessment of the global impact of livestock on biodiversity. Integration within the GLEAM framework will allow assessing environmental performance on multiple criteria, revealing possible trade-offs and avoiding, for instance, the adoption of GHG mitigation options that could be harmful to biodiversity. It will also support the assessment of scenarios in the livestock sector to increase productivity while mitigating impact on climate and biodiversity.

Addressing enteric methane for food security and livelihoods

FAO and the Global Research Alliance on Agricultural Greenhouse Gases are collaborating on a project funded by the Climate and Clean Air Coalition focusing on enteric methane emissions in a 3 regions and 13 countries: Uruguay and Argentina; Ethiopia, Uganda, Tanzania and Kenya; Senegal, Niger, Mali, Burkina Faso and Benin and Bangladesh and Sri Lanka.

The primary focus of this assessment is to respond to the first part of this initiative; identification and prioritization of interventions to reduce enteric methane emission intensity from ruminant systems. This analysis is meant to inform where reductions can be made and to systematically explore emission reduction opportunities with the objective to translate emission savings into benefits for producers.

Three main methodological steps were employed in this study:

  1. Definition of the baseline scenario. Including the selection and characterization of production system, estimation of GHG emissions and emission intensity, and identification of key drivers of low productivity and emission intensity.
  2. Explore the mitigation potential. Identification of system specific interventions consistent with development objectives for improving productivity, addressing enteric methane emissions and assessment of the mitigation potential.
  3. Prioritization of interventions. Prioritization of interventions is undertaken by drawing on modeling results and cost-benefits analysis. It assesses productivity impacts, the potential profitability for farmers in adopting implementing the selected interventions and identifies the implementation barriers.

The study undertakes biophysical modeling and scenario analysis using GLEAM, in order to provide a broad perspective of opportunities and the potential achievable goals in terms of productivity gains and emission intensity reduction potential for the beef sector. The scenario analysis uses the outputs of the biophysical analysis combined with information taken from published literature, existing studies and expert knowledge on potential impacts of each intervention on herd performance and production to assess the emission intensity reduction scenarios.

The case of Uruguay

Uruguay’s beef cattle sector to assess the scale of enteric methane emissions, and identify cost-effective interventions through which methane can potentially be reduced. Significant reductions in emissions can be achieved through the combination of herd and health management, nutrition and feeding management strategies, and genetics. This study estimates a reduction potential of 23%-42% in emission intensity relative to the baseline emission intensity. This reduction potential was achieved by applying a combination of interventions aimed at improving fertility and reproductive status of the herd (controlled mating and early weaning); improving feed quality and availability (winter supplementation and inter-seeding natural pastures with legumes). With this intervention, production (expressed in live-weight terms) increases by 80% compared to the baseline situation. For more information, visit the project website here.

Mitigation in the beef sector in Uruguay. Emission intensity reduction packages for the beef sector in Uruguay. Packages include controlled mating, early weaning, winter supplementation and pasture improvement with legumes.

Improving efficiency in the dairy sector to mitigate climate change

A new methodology, developed by FAO and partners in Kenya, identifies for the first time areas within dairy production where productivity can be improved and greenhouse emissions can be curbed (for example, by changing feed composition or feeding practices, improving the energy efficiency of equipment or the manure management) and explains how those reductions can be measured and reported. This methodology has been certified by Gold Standard, an independent body that evaluates climate projects under the UN’s Clean Development Mechanism and ensures they deliver genuine emission reductions. GLEAM supported the assessment of technical options for the development of the methodology.

Climate Smart livestock investment proposals in Zambia

FAO is working in Zambia and Malawi to identify, assess and upscale climate smart agriculture options. GLEAM was used for the assessment of technical interventions in the livestock sector looking at feed quality, herd and manure management. The model also supported the assessment of climate change impact on feed balances in both countries.

Climate Smart Livestock in Ecuador

Funded by the Global Environmental Facility, the projects aims at capacity development, adoption of better practices and access to new markets and diversification of the livestock sector in Ecuador. The project is based on natural resource use efficiency and carbon sequestration. GLEAM provides the analysis of emission profiles in livestock supply chains and the assessment of options to increase system resilience and productivity.

Greenhouse gas mitigation potential of the world's grazing lands

In collaboration with Colorado State University and together with the Century and Daycent models, GLEAM was used to assess the global mitigation potential of different management practices of grasslands. The Century and Daycent models were used to calculate the changes in soil carbon stocks, soil N2O emissions, and forage removals by ruminants associated with these practices. Three different mitigation practices were assessed: improving grazing management, legume sowing and nitrogen fertilization.

The economics of resilience in the drylands of Sub-Saharan Africa

World Bank, FAO and other partners collaborated to a flagship report on resilience in the drylands of Sub-Saharan Africa. Livestock is the main user of land and a key support for livelihoods in those areas. GLEAM was used to model the development of livestock under climate constraints, to assess feed balances and to analyse the potential of livestock in drylands to meet the projected demand growth.


AnimalChange  was a research project funded by the European Commission’s 7th Framework Program, with 23 partners from Europe, Africa and Latin America. Its objective was to provide a sound basis for the future of livestock under climate change by improving the models, tools and policies used to address this topic. FAO was leader of the Component 4 of the project, which focused on regional assessments and supporting policy makers: the regional assessment and policy making support. GLEAM was used to assess global and regional emissions and mitigation packages.

Cost-benefit analysis of greenhouse gas mitigation in the livestock sector

GLEAM was used to test a selection of mitigation options to estimate the marginal costs of reducing GHG emissions in the ruminant livestock sector at global and regional level. Marginal abatement cost curves were calculated for each of those options, thus providing insights about abatement responses at different carbon prices. GLEAM was used as the main analytical tool to assess the various abatement practices and to integrate data on emission reduction potentials and economic variables from different sources. The most promising abatement options were selected based on their effectiveness and feasibility.

GHG abatement potential of removing trypanosomosis in African cattle systems

SRUC, ILRI, University of Oxford, AP Consultants and FAO worked together to quantify the GHG mitigation effects of intervening against tsetse and trypanosomosis in African cattle. GLEAM was used to quantify the change in GHG emissions and production across a range of cattle systems when trypanosomosis is removed. The results indicate that removal of trypanosomosis can reduce the emissions intensity (i.e. the kg of CO2-eq per kg of edible protein output) by between 2% and 8%, depending on the production system.

Linking GLEAM with economic models to support agricultural GHG Policy

GLEAM has been linked to a farm economic model to quantify the cost-effectiveness of reducing GHG emissions via the use of sexed semen on Scottish dairy farms. The results show that using sexed semen can reduce emissions by increasing the amount of lower emission intensity ‘dairy beef’ produced.