and conventional development focus will lead to a substantial increase in urban land demand, resulting in extensive urban expansion and greater conversion of cropland and pasture to urban land more than any other scenario. Under SSP1, therefore, sustainable food production implies the use of less land-intensive and more productive methods to feed a growing population. Under SSP3 and SSP5, the combination of population growth, deforestation, and unchecked livestock production will result in significantly increased risks, including a heightened risk for pandemics (Berthe et al., 2022).

The assumed growth in total population and in urban population share will lead to an increase in the demand for urban land to 2100 across all SSP pathways (Chen et al. 2020). Under SSP1, the demand for urban land will increase, but begin to decline after 2070, given the assumed eventual decline in population after 2050 under this scenario. Under SSP3, the demand for urban land will initially increase more slowly than under SSP1, given the assumed slow growth in the urban share of the population under SSP3. However, because of the continued population growth to 2100 under SSP3, urban land demand will continue to expand to 2100 and will approach the same level as SSP1 by 2100. Under SSP5, urban land demand is expected to increase significantly due to rapid economic growth, higher income levels, urban population growth, advancements in technology, and emphasis on globalization, leading to more extensive urban expansion and greater losses in crop production, more than other scenarios.

Across all pathways, it is projected that most urban expansion will entail the conversion of particularly productive cropland, followed by forests and then grassland (Chen et al. 2020). By 2100, 55 percent under SSP1 (63 percent under SSP3) of newly expanded urban land is expected to have displaced current cropland, 27 percent (21 percent) forests, and 12 percent (6 percent) grassland. Under SSP5, the land conversion proportions to urban expansion are expected to be 51 percent from cropland, 29 percent from forests, and 15 percent from grasslands. This projected conversion of cropland and grassland into urban land has important implications for crop and livestock production. Chen et al. (2020) show that urban expansion is projected to result in a 1.8– 2.4 percent reduction in global cropland by 2030, and 80 percent of this loss is likely to take place in Asia and Africa. As mentioned above, d’Amour et al. (2017) show that urban expansion is expected to take place on cropland that is 1.77 times more productive than the global average. Under SSP5, the significant increase in urban land demand and the resulting land conversion may lead to the greatest amount of crop production losses among the scenarios, due to the rapid urban expansion and the potential displacement of highly productive cropland.

# _SSPs and projected urban expansion data_

The urban expansion projection data (Chen et al. 2020) are calculated using panel data regression methods based on historical population, urbanization rate, and gross domestic product (GDP) data. Here, the urbanization rate is defined as the percentage of urban population to total population. The settlement extent data (i.e. all artificial cover and paved surfaces, not limited to urban) for the years 1975, 1990, 2000, and 2015 are from the Global Human Settlement Layer (GHSL), a dataset developed by the European Commission. The population and GDP data are from the World Bank and the United Nations. These data are fed into the built panel data regression model to project the built-up areas for each SSP scenario based on the predictions of future population, urbanization rate, and GDP from the SSP database. The projection outputs are then combined with other geographical information and inputted into the Future Land-Use Simulation (FLUS) model to 5