Earth scientists from the University of California, Irvine and other institutions have conducted the most accurate line linking consumers of agricultural products in more affluent countries in Asia, Europe and North America with rising greenhouse gas emissions in less developed countries, mainly in the South.
In an article published today in ScienceResearchers report that trade in emissions from land use – resulting from a combination of agriculture and land use change – grew from 5.1 gigatons of carbon dioxide equivalent (including emissions of other greenhouse gases such as nitrous oxide and methane) in the year 2004 to 5.8 gigaton in 2017.
In the article, the researchers found that changes in land use – including deforestation that absorbs carbon to create space for farms and pastures – contributed about three-quarters of the amount of greenhouse gases caused by world agricultural trade between 2004 and 2017.
“About a quarter of all human greenhouse gas emissions come from land use,” said co-author Stephen Davis, a professor of UCI Earth Systems Science. “Our work shows that a large proportion of these emissions in low-income countries are related to consumption in more developed countries.”
The main sources of emissions from land use change during the study period were Brazil, where the practice of removing natural vegetation, such as forests, to free up space for livestock and farms, has led to significant land use transformations in the country, and Indonesia, where ancient peat preserves carbon has been burned or otherwise eliminated to allow palm oil plants to be grown for export to rich countries.
According to researchers, about 22 percent of the world’s crops and pastures – 1 billion hectares – are used to grow products intended for foreign consumers. Commodities such as rice, wheat, corn, soybeans, palm oil and other oilseeds occupy nearly one-third of the land used for traded goods and contribute about half of the greenhouse gas emissions traded.
The study found shifts in some regions between 2004 and 2017: in the early stages, China was a net exporter of agricultural goods, but by 2017 it had become an importer of both goods and emissions from land use, partly from Brazil. At the same time, Brazil’s exports to Europe and the United States, which in 2004 were the country’s largest trading partners in agricultural goods, declined.
In 2017, last year researched by researchers, the largest source of emissions related to exports was Brazil, followed by Argentina, Indonesia, Thailand, Russia and Australia. The largest net importers of products associated with such emissions were China, the United States, Japan and Germany, followed by the United Kingdom, Italy, South Korea and Saudi Arabia.
In addition to adding greenhouse gases to the atmosphere, human land use practices have led to significant ecosystem disturbances, biodiversity degradation, depletion of water resources and introduced other types of pollution into the local environment.
From an economic point of view, the exporters that produce the most emissions from land use are also heavily dependent on agricultural exports as a contribution to gross domestic product.
Davis said: “We hope this study will raise awareness of the role of international trade in stimulating emissions from land use. In turn, importers may adopt a” buy clean “policy to reduce imports of the most intensive emissions and prevent regions from gaining environmentally destructive trade benefits. We recognize that in a number of regions, including Europe, the United States and China, there have been increased efforts in recent years to improve supply chain transparency, which is a really good sign. “
The project, funded by the National Science Foundation and the U.S. Department of Agriculture, the ClimateWorks Foundation and the Gordon and Betty Moore Foundation, also involved researchers from the University of California, San Diego; University of California, Davis; Stanford University; Tsinghua Chinese University, Beijing Pedagogical University, Peking University, Chinese Academy of Sciences; and the German Ludwig-Maximilian University.