Abstract
Abstract In the future, the land system will be facing new intersecting challenges. While food demand, especially for resource-intensive livestock based commodities, is expected to increase, the terrestrial system has large potentials for climate change mitigation through improved agricultural management, providing biomass for bioenergy, and conserving or even enhancing carbon stocks of ecosystems. However, uncertainties in future socio-economic land use drivers may result in very different land-use dynamics and consequences for land-based ecosystem services. This is the first study with a systematic interpretation of the Shared Socio-Economic Pathways (SSPs) in terms of possible land-use changes and their consequences for the agricultural system, food provision and prices as well as greenhouse gas emissions. Therefore, five alternative Integrated Assessment Models with distinctive land-use modules have been used for the translation of the SSP narratives into quantitative projections. The model results reflect the general storylines of the SSPs and indicate a broad range of potential land-use futures with global agricultural land of 4900 mio ha in 2005 decreasing by 743 mio ha until 2100 at the lower (SSP1) and increasing by 1080 mio ha (SSP3) at the upper end. Greenhouse gas emissions from land use and land use change, as a direct outcome of these diverse land-use dynamics, and agricultural production systems differ strongly across SSPs (e.g. cumulative land use change emissions between 2005 and 2100 range from −54 to 402 Gt CO2). The inclusion of land-based mitigation efforts, particularly those in the most ambitious mitigation scenarios, further broadens the range of potential land futures and can strongly affect greenhouse gas dynamics and food prices. In general, it can be concluded that low demand for agricultural commodities, rapid growth in agricultural productivity and globalized trade, all most pronounced in a SSP1 world, have the potential to enhance the extent of natural ecosystems, lead to lowest greenhouse gas emissions from the land system and decrease food prices over time. The SSP-based land use pathways presented in this paper aim at supporting future climate research and provide the basis for further regional integrated assessments, biodiversity research and climate impact analysis.
Highlights
Agricultural land-use activities have significantly reshaped our planet, as approximately 40% of the terrestrial surface is currently under agricultural use, either as cropland or pasture (Kareiva et al, 2007; FAO 2014)
In addition to potential emission control mechanisms, such as avoided deforestation and improved agricultural management, the land system could contribute to climate change mitigation by enhanced carbon dioxide removal (CDR) through afforestation and bioenergy crop production combined with carbon capture and sequestration (BECCS) (Obersteiner et al, 2001; Smith et al, 2013; Humpenöder et al, 2014)
We concentrate on the detailed presentation and discussion of the Shared Socio-Economic Pathways (SSPs) marker scenarios for the baseline case without climate change mitigation, as well as the RCP4.5 and the RCP2.6 mitigation cases
Summary
Agricultural land-use activities have significantly reshaped our planet, as approximately 40% of the terrestrial surface is currently under agricultural use, either as cropland or pasture (Kareiva et al, 2007; FAO 2014). In addition to potential emission control mechanisms, such as avoided deforestation and improved agricultural management, the land system could contribute to climate change mitigation by enhanced carbon dioxide removal (CDR) through afforestation and bioenergy crop production combined with carbon capture and sequestration (BECCS) (Obersteiner et al, 2001; Smith et al, 2013; Humpenöder et al, 2014) Such additional pressures could pose huge challenges for the sustainability of future land systems. There is uncertainty as to how the demand for agricultural goods will evolve in the future (Valin et al, 2014) and how land use dynamics will respond to an anticipated increase in the demand for ecosystem services (Schmitz et al, 2014) These demands depend strongly on future trends in population growth, dietary preferences, trade, demand for non-food products such as bioenergy, future developments in agricultural yields, and relevant policies. We describe possible future pathways of land use, including the resulting GHG emissions and food prices, under different SSPs and climate policy assumptions based on the implementation of the narratives and quantitative elements of the SSPs into the IAMs
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