While it is understood that cities generate the majority of carbon emissions, for most cities, towns, and rural areas around the world no carbon footprint (CF) has been estimated. The Gridded Global Model of City Footprints (GGMCF) presented here downscales national CFs into a 250 m gridded model using data on population, purchasing power, and existing subnational CF studies from the US, China, EU, and Japan. Studies have shown that CFs are highly concentrated by income, with the top decile of earners driving 30%-45% of emissions. Even allowing for significant modeling uncertainties, we find that emissions are similarly concentrated in a small number of cities. The highest emitting 100 urban areas (defined as contiguous population clusters) account for 18% of the global carbon footprint. While many of the cities with the highest footprints are in countries with high carbon footprints, nearly one quarter of the top cities (41 of the top 200) are in countries with relatively low emissions. In these cities population and affluence combine to drive footprints at a scale similar to those of cities in high-income countries. We conclude that concerted action by a limited number of local governments can have a disproportionate impact on global emissions.

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Feeding humanity puts enormous environmental pressure on our planet. These pressures are unequally distributed, yet we have piecemeal knowledge of how they accumulate across marine, freshwater and terrestrial systems. Here we present global geospatial analyses detailing greenhouse gas emissions, freshwater use, habitat disturbance, and nutrient pollution generated by 99% of total reported production of aquatic and terrestrial foods in 2017. We further rescale and combine these four pressures to map the estimated cumulative pressure, or "footprint", of food production. On land, we find five countries contribute nearly half of food's cumulative footprint. Aquatic systems produce only 1.1% of food but 9.9% of global footprint. Which pressures drive these footprints vary substantially by food and country. Importantly, the cumulative pressure per unit of food production (efficiency) varies spatially for each food type, such that rankings of foods by efficiency differ sharply among countries. These disparities provide the foundation for efforts to steer consumption toward lower-impact foods, and ultimately the system-wide restructuring essential for sustainably feeding humanity.