Land-based Mitigation Technologies
Climate targets will not be met by reducing emissions alone - negative emissions technologies that remove and sequester carbon dioxide are also necessary. Land-based Mitigation Technologies (LMTs) and practices are part of the solution. The main LMTs we are studying in LANDMARC are described below.
Forestry
Forestry, or tree cultivation, is probably the best-known negative emission technology. Trees transform atmospheric carbon dioxide into biomass via photosynthesis. Managed forests in the EU and other industrialised countries currently absorb more carbon than they emit. This is due to historic effects related to regrowth after overexploitation and reforestation, and the resulting age structure. Keeping sequestration rates at current levels, or increacing them, is therefore an effective LMT.
Agroforestry
Agroforestry is the integration of trees with agricultural crops and/or livestock, either simultaneously (grown together) or sequentially (grown one after the other). As with forestry, agroforestry supports the sequestration of carbon in the biosphere but also contributes to important ecosystem services such as improvements in biodiversity, pest control and reduced soil erosion, as well as the economic benefits of a more diverse product range.
BECCS
Bioenergy with Carbon Capture and Storage (BECCS) refers to technologies where biomass is grown to remove CO2 from the atmosphere and oceans, the energy content of the biomass is harvested (for example, through burning), and the carbon emitted is stored below the ground. It has the potential to produce energy while actively offsetting carbon emissions – the carbon absorbed during biomass growth is stored underground. BECSS represents a pivotal technology in most pathways for limiting global warming to 1.5 C. Globally, BECSS could potentially reduce emissions by between 0.5 and 5 GtCO2 per year.
Soil Carbon Sequestration
Soil carbon sequestration (SCS) consists of increasing of the organic carbon content of the soil which results in a net removal of CO2 from the atmosphere. Soil can hold four times more carbon than above-ground biomass, with a global storage potential is estimated to be 2-5 between GtCO2e/yr . Soil carbon can be increased through various strategies, including non-till agriculture, grassland management, cover crops, silvopasture and tree intercropping.
Biochar
Biochar is a type of charcoal, produced by pyrolysis of biomass in the absence of oxygen. Although the process of biochar production releases some carbon dioxide, much of the carbon content of the biomass is retained in the biochar. When added to soil, this carbon is locked away indefinitely. In addition to carbon storage, biochar has multiple benefits for soil health. Research indicates that biochar negative emission potential - globally this could approach 0.7 GtCeq. yr.
Croplands
Farming techniques can have a significant impact on both greenhouse gas emissions, and the amount of carbon stored within the soil. LMTs here can include those that reduce further emissions – for example by avoiding conversion of grasslands into croplands - and those that actively reduce emissions by converting to lower carbon farming techniques. Examples of the latter include no-till farming and dry-seeded rice, both of which can significantly reduce emissions when compared to traditional farming techniques.
Grasslands
Areas of grassland generally have lower associated greenhouse gas emissions than croplands. Grassland management can therefore be considered as both a technique to avoid additional emissions (by avoiding grassland conversion to croplands) or to actively reduce emissions (by converting croplands to grasslands). In many cases, grassland management is used in combination with livestock (grazing/forage production) or in agrosilvopastoral systems, where a combination of grassland management, tree planting/management (agroforestry) and extensive animal husbandry is applied.