Managing farm size as a nature-based solution to restore global crop diversity and reduce inequality

Crop diversity underpins the stability of food supply and the sustainability of agriculture, yet limited understanding of its variability and underlying drivers constrains effective management. Drawing on data from 211 countries over six decades (1961–2020), we show that global crop diversity has generally increased, although one-third of countries experienced declines, and crop evenness decreased in nearly half of the countries. Differences across nations are primarily shaped by farm size, multiple cropping intensity, farmers’ crop income, and crop consumption patterns. Farm size emerges as the dominant factor, reducing global crop diversity by approximately 4%–8% annually from 1961 to 2020 and amplifying global inequalities in crop diversity distribution. Projections indicate a further 3%–10% decline by 2050 relative to 2020 levels. However, this trajectory can be reversed, with effective farm size management yielding a 6%–17% increase in global crop diversity while narrowing inter-country disparities. Such progress is critical to strengthen agricultural stability and advance multiple UN Sustainable Development Goals, including zero hunger, reduced inequality, and responsible consumption and production.