A total of 1.3 million hectares of the Earth’s surface are covered by greenhouses for cultivation in 119 countries and Spain is the second country in the world ranking, only behind China.
This is what nine researchers from institutions in China, Denmark, France and Sweden point out in a study published in the journal ‘Nature Food’.
Humanity has long become accustomed to enjoying tomatoes, cucumbers, berries and melons all year round. In Europe, most of these imports come from Spain, where millions of tons of fruits and vegetables are grown under seas of plastic that stretch across the south of the country.
Global greenhouse cultivation is increasing rapidly, although most of this boom is occurring outside Europe, in low- and middle-income countries in the Global South.
Thanks to a combination of deep learning algorithms and modern sources of satellite images, researchers mapped the amount of land used for greenhouse cultivation around the world.
Their mapping shows that greenhouse cultivation covers at least 1.3 million hectares of the Earth’s surface, almost three times larger than previous estimates.
China, in the lead
Greenhouse cultivation extends to 119 different countries. China leads the world ranking by far (60.4% of the total area), ahead of Spain (5.6%), Italy (4.1%), Mexico (3.3%), Turkey (2, 4%), Morocco (2.3%), South Korea (1.8%), Japan (1.7%), Netherlands (1.4%) and France (1.3%).
In the 1970s and 1980s, large groups of greenhouses were established in the northern hemisphere. Two decades later they began to emerge in the south.
In fact, there has been some stagnation in the north, while the growth trajectory continues in Asia, Africa and Central and South America. In fact, greenhouses in the south represent 2.7 times more surface area than in the north.
“Greenhouse cultivation has become a global phenomenon and everything indicates that it will continue to expand. However, until now, this phenomenon is rapidly going unnoticed and we have large gaps in our knowledge of the dynamics driving this phenomenon,” according to Xiaoye Tong, from the Department of Geosciences and Natural Resource Management at the University of Copenhagen (Denmark) and first author of the article.
According to the researchers, China’s dominance in terms of area is likely related to the country’s socioeconomic development. The study also found that large clusters of greenhouses are located near metropolitan areas.
“The boom in China appears to be closely related to its strong economic performance over the past decade and the rise of an urban population with purchasing power demanding tomatoes, cucumbers and other types of fresh fruits and vegetables. At the same time, farmers who would otherwise not be able to finance this form of cultivation, receive government subsidies and support to build greenhouses and learn cultivation techniques,” says Tong.
The benefits and consequences
Government support for greenhouse growers does not exist only in China, but is found in arid and semi-arid regions that have not traditionally been farmed or seen intensive agriculture before.
In fact, half of all greenhouse growing areas are located in regions with significant resource constraints, such as water scarcity. The researchers note that greenhouse cultivation offers opportunities for local food security and poverty alleviation in the global south.
Due to their controlled environments, greenhouses potentially offer significant advantages in the form of higher and more stable yields, efficient irrigation systems, more precise dosing of fertilizers and nutrients, and better control of crop quality.
But there is also another side to the coin, according to Marianne Nylandsted Larsen, also from the University of Copenhagen: “We know very little about the environmental and social consequences of greenhouse cultivation in the Global South. But we do know that these can include overexploitation of water resources, high energy consumption, contamination of groundwater with pesticides and fertilizers, soil degradation and plastic. Pollution from greenhouses using plastic films and sheets. Furthermore, agricultural working conditions have often been criticized.”
Consequently, researchers advocate considering political regulation of the sector. “In low- and middle-income countries, which represent between 70 and 80% of the total area, there is a lack of regulation of greenhouse cultivation. This problem needs to be addressed,” Tong emphasizes.
Antonio Cerrillo
