Using JULES to Model the Congo Peatlands

The Cuvette Centrale swamp forest around the Congo has the most extensive peatland complex in the tropics, but due to its remoteness the extent and depth of the peat was only recently determined.  The international project CongoPeat has researchers from the UK, the Republic of the Congo and the Democratic Republic of the Congo, working alongside the local people in studying the peatlands to determine how they formed and the possible threats since it is vital that the peat is preserved.  While the peatlands are at least 20,000 years old the peat is thin compared to other tropical peatlands of similar age.  The JULES land surface model has been driven by a reconstruction of the past annual rainfall and meteorological data from a HadCM3 paleo global model to simulate the development of the peatlands.  The model results closely match measurements from the CongoPeat fieldwork and support the hypothesis that a long period of reduced rainfall a few thousand years ago lead to a large loss of peat.  This confirms that a consistently high water table is needed to keep decomposition of the peat to a minimum and hence preserve the peatlands.  Though JULES was unable to recreate the measured Carbon age profile, whereas simpler peat models did, this is only due to its low vertical resolution.  The JULES run was then continued with future climate projections from four global climate models to simulate how the peatlands are likely to change up to 2100.  In each projection there are lower water tables and increased decomposition of peat, but large losses only occur when rainfall is reduced or when drainage is introduced to represent disruption of the peatlands, both of which further lower the water tables.  This is in-spite of increased CO₂ concentration affecting the vegetation by increasing the productivity and litterfall while reducing the amount of transpiration.