Risks of Carbon Loss from the Congo Peatlands due to Climate and Land Use Change

Abstract: The Cuvette Centrale swamp forest has the most extensive peatland complex in the tropics, at least 20,000 years old and estimated to contain 29 Gt of Carbon (approximately equivalent to 3 years of global CO2 emissions), but due to its remoteness the extent and depth of the peat was only recently quantified.  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.  We use the Joint UK Land Environment Simulator (JULES), the land surface component of the UK Earth System model, here setup to form a large amount of peat and to be sensitive to changes in climate.  The long historical simulation, driven by a reconstruction of the past rainfall, shows gains and losses of peat to give a final additional soil depth of 4.27 m and total Carbon amount of 337 Kg C m-2.  It supports the hypothesis that a long period of reduced rainfall a few thousand years ago lead to a notable loss of peat, with JULES losing 2.18 m and 113 Kg C m-2 during this time.  Though JULES was unable to recreate the measured age-depth profile, whereas simpler peat models did, this is only due to its low vertical resolution.  Given the ability of JULES to replicate the observed sensitivity of peatlands to the water table depth, we continued the simulation to 2100 in future projections from 4 global climate models using a high shared socioeconomic pathway (SSP370).  Notable losses in peat occur when rainfall is reduced rather than increased in the future climate, and/or when drainage is introduced to represent disruption of the peatlands (by possible logging, road building or oil prospecting), both of which lower the water table.  With both reduced rainfall and drainage rapid losses of peat are seen, by as much as 0.97 m of additional soil depth and 55 Kg C m-2 of the Carbon amount. This effect is moderated only slightly by the future CO2 fertilization which causes an increase in vegetation productivity and litter and a reduction in evapotranspiration.

Biography: I obtained my PhD in Atmospheric Physics at the University of Manchester and have gone onto postdoctoral positions at a number of Universities, mostly in computer modelling.  Studying air pollution and chemistry, clouds and aerosols, air-sea and air-land interactions, budgets of energy, water and carbon, and vegetation and soil.  At I obtained my PhD in Atmospheric Physics at the University of Manchester and have gone onto postdoctoral positions at a number of Universities, mostly in computer modelling.  Studying air pollution and chemistry, clouds and aerosols, air-sea and air-land interactions, budgets of energy, water and carbon, and vegetation and soil.  At present I’m working for Professor Richard Betts on the CongoPeat, Climate Africa and AmazonFACE projects.