Around the world, tropical forests continue to decline: a pattern which, though it has slowed in recent years, remains one of the most pressing environmental issues of our time.
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Elsewhere though, a remarkable change is happening: tree cover on agricultural land has increased across the globe, capturing nearly 0.75 Gigatonnes carbon dioxide every year.
According to the International Panel on Climate Change (IPCC), agriculture and land-use change account for about 24% of the world's greenhouse gas emissions. Climate change will also have strong impacts on food security in the long-term.
Therefore agriculture needs to reduce its climate footprint. However, experts in the various farm sectors claim that there is only limited scope to reduce emissions from agriculture on the scale that climate scientists say is needed.
At the same time, large forest areas, primarily in the tropics, are still being converted into agricultural land to feed the world's growing population.
One method of greening agriculture, whilst maintaining production is agroforestry - returning trees to agricultural lands - which proponents say carries benefits across a range of different climates and on both cropland and pasture.
The World Bank estimates that 1.2 billion people around the world already depend on agroforestry farming systems, especially in developing countries.
trees on agricultural lands are currently not considered in the greenhouse gas accounting framework of the IPCC.
Because of this, a team of researchers from various institutions in Africa, Asia and Europe carried out a study to assess the role of trees on agricultural land and the amount of carbon they have sequestered from the atmosphere over the past decade.
They said the amount of tree cover on farmed land varied widely from region to region: South East Asia, Central America, eastern South America, and coastal West Africa all had good levels of tree cover on farmland, with eastern China, Western Australia, the North American prairies and northern India having the least trees. Western Europe, the American midwest and Amazonia, South America all had ‘moderate’ tree cover.
Over time, tree cover on farmed land has changed (China has seen increases, as has Indonesia and Brazil, though Argentina, Myanmar, and Sierra Leone have seen large decreases).
Discussing the return of trees to farmed land, the study’s lead author, Robert Zomer of the World Agroforestry Centre said, "Remote sensing data show that in 2010, 43% of all agricultural land globally had at least 10% tree cover, up from eight percent in the preceding decade. Given the vast amount of land under agriculture, agroforestry may already significantly contribute to global carbon budgets." ■