The goals of the Paris Agreement aiming to reduce greenhouse gas emissions will never be achieved without considerable changes in farming practices, according to a study published in Nature (1). Deforestation, conversion of forest to farm land and other changes in land use over the past 60 years have contributed up to a quarter of all human-made emissions released into the atmosphere. Expansion of agriculture in South America and some parts of Asia and Africa, in particular, have pushed this increase.
Typically, land use has ben considered a local issue but is now becoming a matter of global importance. The need to provide food and water to more than six billion people in the world is increasing the area devoted to farming, to the detriment of forests and other natural habitats. Areas for crops, pastures and human settlements have skyrocketed in recent years, with the inevitable loss of biodiversity and increasing quantities of greenhouse gases dumped into the atmosphere.
In a paper published in Nature, a team of researchers unveiled data spanning from 1961 to 2017 regarding how changes in land use affected carbon dioxide and other greenhouse gases released into the atmosphere. “We estimated and attributed global land-use emissions among 229 countries and areas and 169 agricultural products,” said lead author Chaopeng Hong, from the University of California. “We looked into the processes responsible for higher or lower emissions and paid particularly close attention to trends in net CO2 emitted from changes in land use, such as converting forested land into farm acreage.”
Considering worldwide results, global emissions due to changes in land use and farming stayed reasonably constant at around 11 gigatonnes CO2-equivalent from 1961 until 2001. After 2001, however, this pattern changed significantly. Increasing at a rate of 2.4 gigatonnes CO2-equivalent per decade, it reached 15 gigatonnes CO2-equivalent by the end of the period analysed, representing about 25% of the total greenhouse gas emissions.
Localised results, however, varied widely around the world. Latin American and Caribbean, Southeast Asia and sub-Saharan Africa topped global emissions in the period studied, caused by extensive land use changes and a rapid increase in agricultural production. The rest of Asia and the Middle East were responsible for fewer greenhouse gases caused by land use changes, but emissions from farming remained high to keep up with a growing population. On a positive note, Oceania, Europe and North America slowed down in terms of emissions caused by land use changes, but still contributed significantly with greenhouse gases coming from agriculture.
Many of the problems we face now will get worse in the future if the population continues to increase, and the land continues to deteriorate. Drastic changes are needed urgently. Steve Davis, professor of Earth system science at the University of California, is keen to suggest that one of the best ways to reduce emissions caused by agriculture would be to adopt more efficient harvesting methods to increase production yields. “While the situation in low-income countries is critical, mitigation opportunities in these places are large and clear,” said the researcher. “Improving yields on already cultivated land can avoid clearing more carbon-dense forests for cultivation of soybeans, rice, maise and palm oil, thereby drastically reducing land-use emissions in these countries.”
This won’t be easy to achieve, but it’s not impossible. After all, the farming sector has undergone major advances in the past 60 years, often more than doubling production while at the same time reducing the use of pesticides in favour of safer and more effective solutions. The future has got to be driven by improving soil health and farming procedures with digital technologies.
But it’s not just the farming sector that needs to change. The team proposed that some dietary modifications could help as well. Namely, reducing consumption of red meat, which represents only 1% of calories produced worldwide but it accounts for 25% of the world’s greenhouse emissions.
“Feeding the planet may always generate substantial greenhouse gas emissions,” concluded Prof Davis. “Even if we get emissions down to European levels worldwide, with expected population growth, we could still be looking at more than five gigatons of land-use emissions per year in 2100, an amount at odds with ambitious international climate goals unless offset by negative emissions.”
(1) Hong, C., Burney, J.A., Pongratz, J. et al. Global and regional drivers of land-use emissions in 1961–2017. Nature 589, 554–561 (2021). https://doi.org/10.1038/s41586-020-03138-y