The Paris Agreement marked the conclusion of many years of negotiations, setting a global temperature target of “well below 2 °C” and encouraging efforts to “limit increase to 1.5 °C above pre-industrial levels.” However, submitted Nationally Determined Contributions (NDCs), countries’ pledges to implement emissions reductions, fall short of the goal. Current commitments are more compatible with 2.5 °C to 3 °C of warming by 2100. To limit warming to 1.5 °C (and 2 °C), countries will need to plan for a more rapid transformation of their national energy, industry, transport and land-use sectors.
The land sector, commonly referred to as ‘agriculture, forestry, and other land uses’ (AFOLU) is responsible for about 25% of net anthropogenic greenhouse gas (GHG) emissions, with approximately half from agriculture and half from land use, land-use change and forestry (LULUCF). LULUCF emissions represent the net balance between emissions from land-use change and carbon sequestration from the regeneration of vegetation and soils. Although the AFOLU sector generates considerable emissions, the residual terrestrial sink (accumulation of carbon in the terrestrial biosphere excluding land sinks from LULUCF) also currently sequesters about 30% of annual anthropogenic emissions, making land vitally important for generating ‘negative emissions’ — that is, more carbon dioxide removals (CDR) than emissions. In addition to GHG impacts, land-use generates biophysical impacts that affect the climate by altering water and energy fluxes between the land and the atmosphere. Furthermore, the AFOLU system provides important ecosystem goods and services such as air and water filtration, nutrient cycling, habitat for biodiversity, and climate resilience.
Of the countries that ratified and submitted NDCs, a majority included land-sector mitigation, providing 10–30% of all planned emissions reductions globally in 2030. Land-based mitigation measures largely fall into four categories: reduced land-use change, CDR through enhanced carbon sinks, reduced agricultural emissions, and reduced overall production through demand shifts. Most countries included reduced land-use change, afforestation and forest restoration, a few included soil carbon sequestration and reduced agricultural emissions, yet none mentioned demand-side shifts. As countries submit new or revised NDCs by 2020 and prioritize climate strategies and investments, it is helpful to take stock of the scientific and technological advancements in key sectors, particularly in the land sector where there are many opportunities for environmental and social co-benefits.
Building on existing studies of mitigation pathways and mitigation potentials in the land sector, in a recent article published in Nature climate change and in which the Ikerbasque Professor and BC3 Scientific Director Maria Jose Sanz takes part, it is provided a comprehensive assessment of all land-based activities (agriculture, LULUCF and bioenergy), and their possible contributions to the Paris Agreement temperature target of 1.5 °C. In this work four complementary analyses are conducted: (1) review of 1.5 °C scenarios across all sectors, (2) comparative analysis of top-down modelled pathways in the land sector, (3) bottom-up assessment and synthesis of landsector mitigation potential and (4) a geographically explicit roadmap of priority mitigation actions to fulfil the 1.5 °C land-sector transformation pathway by 2050, informed by the first three analyses.
For more information: https://doi.org/10.1038/s41558-019-0591-9