Use of land

One of the emission sectors defined by the IPCC concerns agriculture, forestry and other land use (AFOLU). It is natural to see this also in the context of undisturbed nature, which anyway is affected by human activity through emissions of gases and aerosols. For example, emissions of CO₂ increase the growth of green plants by stimulating photosynthesis.

An article in PNAS [L81] from 2017, Natural climate solutions [L80], addresses both emission reduction opportunities and measures to stimulate carbon uptake. The potential for reducing greenhouse gases in the atmosphere using 20 different measures within the AFOLU sector is assessed in relation to two different cost limits. With a maximum cost of $10 per tonne of reduced emissions per year, one can achieve an annual reduction in emissions of 4.1 Pg CO₂ equivalents per year. This corresponds to 8.4% of the total emissions in 2010. If the cost limit is increased to $100 per tonne of reduced emissions per year, the annual emission reduction is increased to 11.3 Pg CO₂ equivalents per year (23% of emissions in 2010). The measures recommended take into account the conservation of biological diversity, and that food production and production of plant fibre should not be weakened. The most important measures include restoration of damaged forest and bog, conservation of pristine forests and bogs, as well as more sensible use of nitrogen fertilisers.

A technology that in the long term will be able to reduce land use in the agricultural sector is vertical farming [L82]. In such farms, the plants are placed in many floors above each other, and live in a carefully controlled environment. Temperature, light conditions and nutrient supply are adapted to the needs of the plants. Water and nutrients are added directly to the roots without any need for soil. In such a carefully controlled environment, the need for chemical control (pesticides) of unwanted organisms can be significantly reduced. However, this technology has many disadvantages. Such farms require large investments and a lot of energy in the form of artificial light for the plants. With energy that is currently so dependent on polluting coal and gas power plants, vertical farms are unlikely to contribute to lower emissions of greenhouse gases in the near future. But when the energy problem is solved, the areas that will be released can be planted with forests and contribute to increased uptake of CO₂.

Latest update: 2021-08-13