Trees on agricultural lands - also known as agroforestry systems - have the potential to contribute to climate change mitigation while improving livelihoods and incomes and providing invaluable ecosystem services at the same time. The World Bank estimates that globally 1.2 billion people depend on agroforestry farming systems, especially in developing countries. However, trees on agricultural lands are not considered in the greenhouse gas accounting framework of the International Panel on Climate Change (IPCC), which instead only notes that agriculture and land-use change account for about 24% of the world's greenhouse gas emissions.
In the tropics, forests are being converted into agricultural land to feed their populations, which western elites don't want. For these reasons, agricultural practices that can significantly reduce carbon emissions are in high demand. An obvious one may have been there all along, and could explain why global warming has not happened.
Remote sensing data show that in 2010, 43% of all agricultural land globally had at least 10% tree cover, up 25 percent from the preceding decade. Given the vast amount of land under agriculture, agroforestry may already significantly contribute to global carbon budgets.
Regional differences are significant, the distribution of tree cover on agricultural land depends on climatic conditions in different parts of the world. High tree cover is found in humid areas such as South East Asia, Central America, eastern South America, as well as central and coastal West Africa. Tree cover on agricultural land was moderate in south Asia, sub-humid Africa, central and western Europe, the Amazonia and mid-west North America. On the other hand, low tree cover was found in east China, northwest India, west Asia, the southern border of the Sahara Desert, the prairies of North America and southwest Australia.
High average carbon mass levels were to be found in 26 countries in the humid tropics, with the Democratic Republic of Congo, Papua New Guinea, Malaysia and Indonesia in the lead. On the other hand, 60 countries found in arid and desert parts of the world around the Sahara Desert in North Africa, the Kalahari in southern Africa, Middle East, as well as central and southern Asia recorded low carbon levels over the ten-year period.
Citation: Zomer R J, Neufeldt H, Xu J, Ahrends A, Bossio D, Trabucco A, van Noordwijk M and Wang M. "Global Tree Cover and Biomass Carbon on Agricultural Land: The contribution of agroforestry to global and national carbon budgets". Scientific Reports 6, Article number: 29987 (2016). doi:10.1038/srep29987