Over the past two centuries, humans have converted or modified 70% of the world’s grasslands, 50% of the savannah, 45% of temperate forests and 27% of tropical forests for farming and grazing activities. Today, of the 13 billion hectares of ice-free land in the world, 46% is used by agriculture and forestry, of which 52% is considered moderately or severely affected by soil degradation. Over the past 20 years alone global croplands and pastures have increased by 154 million hectares due to increased demand for food from rising populations and income levels, particularly in emerging markets. This has also led to increased demand for water as diets shift from a predominantly starch-based one to a water-intensive one comprising mainly of dairy and meat products.
Intensive land conversion for agricultural production
Intensive land conversion for agricultural production has come at a cost to ecosystem services including carbon sequestration and water quality and quantity. Since the industrial revolution around 270 gigatons (Gt) of carbon has been released into the atmosphere, of which around 136 Gt is primarily due to deforestation, the conversion or drainage of natural ecosystems for example wetlands, biomass burning and the loss of soil organic carbon. Land degradation is creating a vicious cycle: Intensive production and conversion of land increases emissions, which increases the magnitude and frequency of extreme weather events such as flooding and droughts, which in turn results in losses of soil and vegetation and subsequently further land degradation. The result is more land needing to be converted for agricultural production. The impacts of this vicious cycle are severe both economically and politically: global losses due to land degradation are estimated to be USD 6.3-10-6 trillion per year while 50 million people will face displacement in the next 50 years due to desertification and land degradation.
Reducing the costs of land degradation
To reduce this vicious cycle the United Nations states the need to focus on reducing land degradation and associated emissions through land use change, land management and restoration, and land use planning.
Land use change: Global soil acts as a ‘carbon safe deposit box’ with more carbon in soil than in all the atmosphere and plant life combined: there is around 2,500 billion tons of carbon in the soil compared to 800 billion tons in the atmosphere and 560 billion tons in plants. Reducing the rate of loss and degradation of forests, peat lands and mangroves will reduce emissions, for instance the preservation of tropical forests would reduce emissions by 1.3-4.2 Gt of carbon dioxide-equivalent per year in 2030.
Land management and restoration: There are many opportunities to reduce emissions in agricultural production. For instance reducing the use of fertilizer applied reduces the amount of emissions associated with its production while more efficient irrigation reduces energy costs and emissions. In addition the planting of forests in agricultural areas reduces emissions as they act like carbon sponges while purifying water.
Land use planning: There are multiple demands on land from both public and private stakeholders. Therefore strong institutions are required to engage all stakeholders in land use planning to ensure weather and climate proofing activities or land rehabilitation projects are undertaken to halt and reverse land degradation. The private sector can contribute in particular by identifying low-cost mitigation opportunities and manage resilience to climate change and associated risks.
We need to use existing resources, including valuable agricultural land more efficiently, to mitigate climate change and avoid costly economic and political impacts.