The Sea of Greenhouses in Almeria
The province of Almería in southeastern Spain experiences some of the driest conditions in Europe. Yet with access to groundwater and an abundance of sunshine, it has become a major hub for greenhouse agriculture.
On May 24, 2022, the Operational Land Imager-2 (OLI) on Landsat 9 captured these natural-color images of a sea of plastic greenhouses around the town of El Ejido. The city is located on a small coastal plain called Campo de Dalías, which has one of the highest concentrations of greenhouses in the world.
Greenhouses (invernaderos in Spanish) are a relatively new phenomenon. In the 1950s, Campo de Dalías was mostly covered in scrub vegetation, pasture and a few small patches of seasonal crops grown outdoors. Farmers began experimenting with adding layers of sand and mulch to the soil with a plastic cover in the 1950s and 1960s, initially to protect soil and plants from damaging winds and salty groundwater. They soon realized that crops grown under plastic were much more productive than their outdoor counterparts because the soils stayed warmer and held more moisture.
The use of greenhouses spread rapidly over the following decades as new innovations, such as drip irrigation, the use of artificial soils, and hydroponics, boosted crop yields. According to some estimates, Almería’s greenhouses now produce between 2.5 and 3.5 million tonnes of fruit and vegetables a year, enough to make it a major source of out-of-season tomatoes, peppers, cucumbers and melons for the people of all of Europe.
By some estimates, Almería’s greenhouses now cover over 40,000 hectares (150 sq mi) – almost all of Campo de Dalías. They have also spread to neighboring regions. The greenhouses cover so much area that they probably even caused a localized cooling effect as the white roofs reflect a significant amount of sunlight.
Using observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on NASA’s Aqua and Terra satellites, researchers at the University of Almería calculated that the surface albedo of Almería had increased by almost 10% between 1983 and 2006 due to the high reflectivity of greenhouses. They concluded that this likely contributed to a cooling effect of 0.3 °C (0.5 °F) per decade in Almería, compared to an increase of 0.5 °C per decade in the region.
NASA Earth Observatory images by Lauren Dauphin, using US Geological Survey Landsat data. Story of Adam Voiland.