Abstract: Ruminant production systems are important producers of food, support rural communities and culture, and help to maintain a range of ecosystem services including the sequestering of carbon in grassland soils. However, these systems also contribute significantly to climate change through greenhouse gas (GHG) emissions, while intensi- fication of production has driven biodiversity and nutrient loss, and soil degradation. Modeling can offer insights into the complexity underlying the relationships between climate change, management and policy choices, food production, and the maintenance of ecosystem services. This paper 1) provides an overview of how ruminant systems modeling supports the efforts of stakeholders and policymakers to predict, mitigate and adapt to climate change and 2) provides ideas for enhancing modeling to fulfil this role. Many grassland models can predict plant growth, yield and GHG emissions from mono-specific swards, but modeling multi-species swards, grassland quality and the impact of management changes requires further development. Current livestock models provide a good basis for predicting animal production; linking these with models of animal health and disease is a prior- ity. Farm-scale modeling provides tools for policymakers to predict the emissions of GHG and other pollutants from livestock farms, and to support the management decisions of farmers from environmental and economic standpoints. Other models focus on how policy and associated management changes affect a range of economic and environmental variables at regional, national and European scales. Models at larger scales generally utilise more empirical approaches than those applied at animal, field and farm-scales and include assumptions which may not be valid under climate change conditions. It is therefore important to continue to develop more realistic representations of processes in regional and global models, using the understanding gained from finer-scale modeling. An iterative process of model development, in which lessons learnt from mechanistic models are ap- plied to develop ‘smart’ empirical modeling, may overcome the trade-off between complexity and usability. De- veloping the modeling capacity to tackle the complex challenges related to climate change, is reliant on closer links between modelers and experimental researchers, and also requires knowledge-sharing and increasing technical compatibility across modeling disciplines. Stakeholder engagement throughout the process of model development and application is vital for the creation of relevant models, and important in reducing problems re- lated to the interpretation of modeling outcomes. Enabling modeling to meet the demands of policymakers and other stakeholders under climate change will require collaboration within adequately-resourced, long-term inter-disciplinary research networks

Abstract: The report presented here provides an inventory of reports and conference papers  produced by the partners of the livestock and grassland modelling theme (LiveM) of the  Modelling European Agriculture with Climate Change for Food Security (MACSUR)  knowledge hub. The findings presented illustrate the diverse nature of the multidisciplinary  LiveM research community, and provide a reference source for those seeking  to identify and pull out farm-level modelling outputs from the work of MACSUR and its  partners. The survey of farm-scale outputs from LiveM revealed the interdependent, dual  role of a knowledge hub: to increase the capacity of modelling to meet stakeholder and  societal needs under climate change, and to apply that increased capacity to provide new  understanding and solutions at the policy and (the focus here) farm scale. While capacity  building work across disciplines is time-consuming, difficult, and to a large extent invisible  to stakeholders, such work is vital to ensuring that subsequent scientific outcomes reflect  best practice, and integrated expertise. Long term, sustained funding of network-based  capacity building activities is highlighted as essential to ensuring that the farm-scale  modelling work highlighted here can continue to build on ongoing improvements in model  quality, flexibility and stakeholder relevance.