Sustainability and productivity in global livestock grazing: Current challenges and future pathways

As the global population grows, becomes more affluent, and increasingly consumes planet's limited natural resources, the pressure on ecosystems intensifies. Producing food sustainably for everyone is challenging but possible if existing production structures and mindsets are changed. Reducing meat production has been reported to be one of the key solutions in addressing environmental challenges because it is highly resource-intensive, requiring significant amounts of land, water, and feed. Global livestock production has increased nearly fivefold since the 1960s, while the population has only tripled, thus amplifying the strain on ecosystems. Animal-source foods are vital for many diets, yet excessive meat consumption in affluent nations harms health and the environment. Grazing, in particular, is a major land user and influences ecosystems, but the exact locations where it could sustainably occur remain unclear. This dissertation examines the opportunities and challenges associated with livestock grazing in terms of efficiency and environmental aspects. It assessed the distribution of biomass availability for livestock consumption, carrying capacity and its changes, as well as grazing intensities at a global scale. Concurrently, this work identified areas experiencing overgrazing and regions with potential for increased grazing. The research also analyzed the competition between livestock and crop production, exploring how shifts in land-use could increase food production capacity. Furthermore, the dissertation investigated the limits of biodiversity-friendly grazing and explored where removing grazers and allowing ecosystem restoration would enhance carbon sequestration. The findings reveal significant sustainability issues in many grazing lands due to overgrazing, decreasing carrying capacity, inefficiency, or carbon emissions. Strategic land-use changes could significantly increase global food production while minimizing harmful environmental impacts. The research highlights regions where shifting grazing lands to croplands could most effectively benefit the food supply. It also underscores the complex trade-offs between production and biodiversity conservation, as achieving biodiversity goals requires reduced grazing pressure, impacting production levels of meat and milk. Reducing beef production on grazing lands that were formerly forests could lead to substantial carbon sequestration, while removing grazing in naturally nonforested areas would yield less significant environmental benefits, suggesting that targeted interventions are necessary for optimal outcomes. While there is a strong rationale for reducing livestock production, this work clarifies where desirable changes could be most effectively implemented and where current grazing practices potentially remain important. This research also provides novel datasets and maps for future research, which should also consider social, economic, and cultural factors in land-use planning.