Previously undetected small-scale greenhouses are an unknown environmental threat

Greenhouse cultivation has been expanding rapidly in recent years, being crucial for food security but raising environmental concerns. Yet, currently little knowledge exists on its global extent and possible drivers of the expansion. Here, we present a global assessment of greenhouse cultivation and map 1.3 million hectares of greenhouse infrastructures in 2019 using commercial satellite data at 3 m resolution, including both large and small scale greenhouse infrastructure. We show that only 61% are concentrated in large greenhouse clusters, and that the remaining 39% are small-scale greenhouse cultivation, which are challenging to detect with public satellite data. By studying the temporal development of the 65 largest clusters (> 1500 ha), we show a surge in greenhouse cultivation in the Global South since the early 2000s, including a dramatic increase in China, which accounts for 60% of the global coverage. Our assessment raises awareness that the true extent of areas polluted by greenhouse plastic is much larger than previously thought, with wide-ranging implications on environmental and socioeconomic conditions.