Carbon, vegetation, agriculture and water

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Key policy issues

  • How do climate change and land-use management affect the land productivity of current and future agricultural land?
  • What is the role of the terrestrial biosphere in the global carbon cycle, how will it change in time as a result of climate and land-use change?
  • What is the combined effect of climate change and socio-economic development on water demand and availability, and associated agricultural production?

Description of Carbon, vegetation, agriculture and water

LPJmL is the carbon, vegetation, agricultural and hydrology model in IMAGE 3.0 and consists of the three components: Carbon cycle and natural vegetation, Crops and grass, Water.

Within the Earth system, the terrestrial biosphere is the component that bears the most visible impact of human activity. Large proportions of the land surface and the terrestrial vegetation have been converted for human use, for instance, to cropland and urban areas.

Agriculture, terrestrial carbon, water and nutrient cycles were separate modules in previous versions of IMAGE and thus interactions were not adequately covered. IMAGE 3.0 covers natural and agricultural terrestrial ecosystems, and associated carbon and water dynamics via the link with the dynamic global vegetation, agriculture and water balance model LPJmL (Lund-Potsdam-Jena model with managed Land; Sitch et al., 2003; Gerten et al., 2004; Bondeau et al., 2007). This enables more detailed and process-based representation of the interacting dynamics in vegetation, carbon and agricultural production, and extends the model scope to terrestrial freshwater dynamics.

LPJmL is one of the most extensively evaluated dynamic global vegetation models (DGVM) and is widely applied either separately or linked to other models. To show the complex dynamics in the terrestrial biosphere and to reflect the historical IMAGE modules, LPJmL is described in three components: carbon cycle and vegetation; agricultural land use; and terrestrial freshwater flows.

IMAGE 3.0 and LPJmL are linked through an interface that enables close and consistent interaction between the two models in annual time steps. An even more direct link to simulate detailed land-atmosphere interaction would require higher temporal resolutions also in other IMAGE components (e.g., the climate model), which is not necessarily congruent with the philosophy of an integrated assessment model. Incorporating nutrient cycles and improving representations of grassland management in LPJmL will require further adjustments to other IMAGE 3.0 components, and will increase consistency.

Composition of Carbon, vegetation, agriculture and water

  1. Carbon cycle and natural vegetation
  2. Crops and grass
  3. Water