MANY FOOD-ENERGY-WATER (FEW) NEXUS STUDIES FOCUS ON GLOBAL- OR NATIONAL-SCALES, OR ON AGRICULTURAL PRODUCTION, RECOGNIZING THAT THE FOOD SYSTEM IS RESPONSIBLE FOR &GT;10 MILLION PREMATURE DEATHS GLOBALLY (FOROUZANFAR ET AL 2016), CONTRIBUTES TO 15% U.S. ENERGY USE (CANNING ET AL 2010), 30% OF GLOBAL GHG EMISSIONS, AND, WATER STRESS, WATER POLLUTION AND LAND-USE CHANGE (VERMEULEN ET AL 2012, HU ET AL 2018). HOWEVER, RECENT STUDIES SHOW CITIES--WHERE A MAJORITY OF FOOD CONSUMPTION AND FOOD WASTE GENERATION, AND SOME AGRICULTURE, OCCURS--CAN BE A LARGE LEVERAGE POINT TO TRANSFORM THE FEW NEXUS. FOR EXAMPLE, MOHAREB ET AL (2018) ESTIMATE THAT US CITIES COLLECTIVELY DIRECTLY INFLUENCE TWO-THIRDS OF THE FOOD SECTOR GHG EMISSIONS. SPECIFICALLY, THREE KEY URBAN FOOD SYSTEM ACTIONS TAKEN AT THE CITY-SCALE HAVE THE POTENTIAL TO SUBSTANTIALLY IMPROVE LOCAL AND GLOBAL FEW SUSTAINABILITY OUTCOMES:I) BEHAVIORAL NUDGING TOWARD HEALTHY (H) AND ENVIRONMENT-FRIENDLY (E) DIETS: TRANSITIONS TO A 25% VEGETARIAN DIET IN THE US IS ESTIMATED (METHODS BOYER &AMP; RAMASWAMI 2018) TO REDUCE GHG EMISSIONS BY 7%, LAND-USE BY 4%, WHILE INCREASING WATER USE BY 9%, AND HAVING HEALTH BENEFIT (TILMAN &AMP; CLARK 2014). SEVERAL COMMUNITIES ARE IMPLEMENTING PROMISING DIET CHANGE INTERVENTIONS; HOWEVER, NEW SCIENCE IS NEEDED TO ENHANCE PARTICIPATION, MEASURE PERSISTENCE, AND ASSESS THE EXTENT TO WHICH REAL-WORLD (VS SCENARIO) SHIFTS TOWARD HEALTHY DIETS INTERSECT WITH ENVIRONMENT-FRIENDLY DIETS.II) NEW "FIT-FOR-PURPOSE" FOOD-WASTE VALORIZATION TECHNOLOGIES ARE BEING DEVELOPED THAT GENERATE A RANGE OF PRODUCTS, INCLUDING (AT THE SIMPLEST LEVEL) BIOGAS REPLACING DIRTY COOKING FUELS OR FOSSIL FUELED-ELECTRICITY; WASTE-DERIVED LIQUID FERTILIZERS AND BIOCHAR COMBINATIONS THAT CAN OUTPERFORM CHEMICAL FERTILIZERS; ANIMAL FEED THAT CAN BE CYCLED BACK INTO FOOD PRODUCTION. WHILE PREVENTING WASTE IS BEST, FOOD-WASTE VALORIZATION TECHNOLOGIES CAN YIELD EXCEPTIONALLY HIGH ENVIRONMENTAL (E) BENEFITS AT THE FEW NEXUS, GIVEN FOOD WASTE ACCOUNTS FOR 34% BLUE WATER-, 31% LAND-, 35% FERTILIZER, AND 35% ENERGY USE/GHGS RELATED TO INDIVIDUAL'S FOOD-RELATED RESOURCE USE (BIRNEY ET AL 2017). ADVANCED FOOD WASTE VALORIZATION TECHNOLOGIES (E.G., NUTRIENT AMENDED BIOCHARS) HAVE THE POTENTIAL TO DO EVEN BETTER, TRIGGERING A VIRTUOUS CYCLE OF BENEFITS IN FEW SYSTEMS, BY IMPROVING FARM YIELD WITH REDUCED WATER AND FERTILIZER USE. HOWEVER, SUCH QUANTIFICATIONS REQUIRE LINKING LAB STUDIES WITH FIELD STUDIES AND SYSTEMS TOOLS, WITH ACTUAL IMPACT SHAPED BY PEOPLE PARTICIPATING IN WASTE SEPARATION.III) LOCALIZED AND DISTRIBUTED URBAN AGRICULTURE ARE HYPOTHESIZED TO OFFER MANY LOCAL BENEFITS: LOCAL FOOD PROVISIONING/NUTRITION (BENEFITING HEALTH, H), URBAN COOLING THAT REDUCES ENERGY USE AND HUMAN HEALTH RISKS DURING EXTREME HEAT EVENTS, ENHANCING COMMUNITY-RESILIENCE (R), AND, HAPPINESS/WELLBEING (W) BENEFITS (SIEGNER ET AL 2018). HOWEVER, THERE IS A FUNDAMENTAL LACK OF DATA AND SCIENCE AT THE MUCH SMALLER SPATIAL SCALES OF URBAN FARMS, AND THE DISTRIBUTED NATURE OF THESE FARMS, WHEREIN HUNDREDS OF FARMERS/GARDENERS USING DIVERSE FARMING PRACTICES ARE GROWING FOOD IN BACKYARD VEGETABLE GARDENS, COMMUNITY GARDENS VERSUS COMMERCIAL FARMS IN THE URBAN PERIPHERY. IN CONTRAST, HEAT ISLAND PHENOMENA HAVE BEEN STUDIED AT COARSER SCALES OFTEN WITH A FOCUS ON GROUND TEMPERATURES (IMHOFF ET AL 2010), WHILE AIR TEMPERATURES ARE OF INTEREST TO PUBLIC HEALTH (XU ET AL 2017). SUCH INTRA-URBAN SPATIAL DETAIL MATTERS BECAUSE THE SPATIAL DISTRIBUTION OF THESE BURDENS AND BENEFITS IMPACTS SOCIAL EQUITY, E.CITY FOOD SYSTEM ACTIONS: WHAT WOULD HAPPEN IF ALL CITIES UNDERTOOK ALL THREE ACTIONS? THEY COULD SUBSTANTIALLY REDUCE WATER-, ENERGY- AND FERTILIZER-USE, AND ASSOCIATED AIR POLLUTION AND GHG EMISSIONS--TRANSFORMING THE FEW NEXUS AT LEVELS COMPARABLE WITH MAJOR CHANGES IN AGRICULTURE. AND, THEY CAN ADVANCE MULTIPLE WELLBEING, HEALTH, ENVIRONMENT, COMMUNITY-RESILIENCE, AND EQUITY (WHERE) OBJECTIVES WITHIN CITIES. THUS URBAN FOOD SYSTEM ACTIONS ARE LARGE TRANSFORMATIVE LEVERS IN THE LOCAL-TO-GLOBAL FEW NEXUS, WHICH ARE MOTIVATED BY THE PROMISE OF ADVANCING MULTIPLE WHERE BENEFITS WITHIN CITIES. INDEED, MORE THAN 100 US CITIES, &GT;1500 WORLD CITIES AND INTERNATIONAL ORGANIZATIONS ICLEI AND UN ENVIRONMENT ARE PRESENTLY ENGAGED IN URBAN FOOD ACTION PLANNING AND FINDING THAT THE FUNDAMENTAL SCIENCE, DATA, AND KNOWLEDGE ARE LACKING. HENCE, THE FOCUS OF THIS INFEWS PROPOSAL ON URBAN FOOD SYSTEM ACTIONS IN THE CONTEXT OF THE LOCAL-TO-GLOBAL FEW NEXUS SUSTAINABILITY.