Title: Long-term land-use change and feedback to the global climate system

Goal/Aim:

· Develop methodologies and a regional case study for the reconstruction of land-use change over long time scales (10²-10³ years) using a combination of palaeoecological, historical and remote sensing techniques.

· Participate in a modelling exercise where long-term land-use change contributes to the construction of past and future climatic scenarios.

Background: Traditionally the biosphere has been viewed as a passive recipient of climate change. However, recent research into biophysical and biochemical feed-backs to the climate system has suggested that these feed-backs can account for significant amplification and even initiation of climate trends that cannot be explained by physical climate models. Vegetation dynamics and biome shifts are the most relevant aspects of the biosphere in this respect, but animals are important in the control they exert on biome boundaries, particularly the savannah-forest and savannah-grassland ecotones. A key arctic ecotone is the forest limit that is sensitive to extreme climatic events, outbreaks of insect pests and ungulate browsing pressure. There are significant differences in albedo between tundra and forest areas that feedback into the climate system.

The project will form part of a new international initiative where the research group LUCC (Land Use and Cover Change Focus 1 Land Use Dynamics) collaborates with PAGES (Past Global Changes). The student will have the opportunity to join an active international research community and make many valuable contacts. The LUCC community at a recent workshop endorsed the need to consider longer time scales for a better understanding of non-linear changes and system behaviour. There is a need to create an overlap between the LUCC (historical data) and the PAGES (palaeorecords) time series to allow for "inter-calibration" of data. There is a need to stimulate interdisciplinary collaboration which will be aided by future LUCC-PAGES initiatives.

Project Description: The project involves the reconstruction of land-use changes over longer time scales using techniques of remote sensing and palaeoecological reconstruction. Remotely sensed data from a test area will be used to calibrate recent palaeoecological (chiefly pollen data). Then sub-fossil palaeoecological data will be used to reconstruct former land use dynamics. Existing data will be used from regional pollen databases. Detailed case study reconstructions will be upscaled using biomisation techniques and the data will be used for input into regional and global climatic simulation models to explore their sensitivity to past changes in land use. The role of land use dynamics in potential future climatic scenarios will also be investigated.

Methodology: Remote sensing. Interpretation and quantitative analysis of historical maps. Interpretation and mapping of pollen data preserved in lake sediments. Biomisation of pollen data and upscaling of data for incorporation into regional and global climatic simulation models.

Copenhagen University contact person incl. Email Professor John Anderson [email protected]