Landscape scale genomic-environment diversity data to model existing and novel agri-systems under climate change to enhance food security in Ethiopia Context: Ethiopia has historically been the world's largest recipient of targeted food aid, yet little food-insecurity has been reported for the southern Ethiopian highlands even during the devastating famines of the 1980s. Today, the agri-systems of the southern Ethiopian highlands successfully support one of the highest rural population densities in Africa (up to 1000persons/sqkm). Here, we investigate the landscape scale dynamics, interactions and resilience of these agri-systems, using interdisciplinary environmental modelling, crop genomics and natural capital approaches to understand how best to manage their response to climate change whilst continuing to provide food security for a growing Ethiopian population - predicted to reach 172 million by 2050. Ethiopia is an important center of diversity for food crops, with an agricultural history defined by the domestication of numerous species including coffee, tef and enset. Southern Ethiopian agri-systems include more than 78 cultivated species encompassing roots, tubers, cereals, vegetables, fruits and pulses, including a very high proportion of indigenous crops. Typical farms average 19 different crop and livestock species underpinned by over 120 species of useful trees and shrubs co-occuring across the homegarden landscape. Research on individual crop species also indicates extremely high diversity, for example we have recorded >600 enset varieties, including up to 24 on a single farm, and 37 varieties of yam. This diversity aggregated at multiple scales may be the key to the past resilience of the southern Ethiopian highlands in times of famine, and the source of future resilience to climate change.  Aims: Building on previous research, we hypothesize that the biotic drivers of high agri-system productivity and resilience are: (1) cultivation of a high crop diversity within farms, (2) cultivation of high genetic diversity within crop species and (3) cultivation practices that commonly involve diverse mixes of annual and perennial, indigenous and alien, semi-domesticated and domesticated crops. This rich diversity at multiple scales can in principle support food security and sustainable intensification whilst buffering seasonal food deficits, emerging pests and diseases and facilitating agronomic adaptation; despite an average farm size of only 0.9 hectares and very few off-farm inputs such as irrigation systems and fertilizers.  In contrast to this indigenous diversity, farmers also grow highly domesticated introduced crops such as maize, avocado and banana, providing an ideal opportunity to evaluate these hypotheses. These crops are high yielding but likely to contain less genetic diversity. This may limit their capacity for adaptation to new or altered environments and their resilience to climate change. The prevalence of these introduced crops is increasing, together with a reported loss of indigenous crop diversity and a shift away from agro-forestry. The impacts of these trends as well as the projected impact of climate change on the resilience of Ethiopian agri-systems is unknown.  Applications and benefits: Our research will generate landscape scale environmental suitability, genomic and natural capital data to underpin a decision making tool for sustainable agri-system development and climate adaptation in the region. By enhance future resource provision and resilience, we will generate clear economic and social impact on the livelihoods they support. The novel methods employed here will be of both broader academic interest in the fields of agronomy, crop breeding and conservation and provide immediate knowledge-transfer and resources to enhance Ethiopia's research capability. Most importantly, capitalizing on our strong existing UK-Ethiopian partnerships and links to regional government we will seek development and implementation of science-based regional agri-systems strategy to bring immediate impact within the life of the project. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.