Department of Geography

The global carbon cycle

The natural carbon cycle plays a crucial role in the climate system. The carbon ‘sinks’ in the terrestrial biosphere and the oceans act to absorb about one half of all our anthropogenic carbon emissions. However, these complex biological, physical and chemical processes are sensitive to climate such that the fluxes of carbon between the atmosphere and the terrestrial biosphere and oceans may change in response to changing temperatures, patterns of rainfall, surface energy budgets and atmospheric composition. Research at Sussex seeks to quantify some of the key processes in the carbon cycle so that we are better able to predict their future behaviour as we enter the uncharted territory of the anthropocene.

Carbon and permafrost

Our research aims to quantify how permafrost thaw impacts biogeochemical cycles in contrasting boreal and Arctic ecosystems. We are especially interested in determining the relative fluxes of carbon dioxide versus methane in free-draining ecosystems versus peatland systems, as the two gases have very different global warming potentials. The influence of forest fire on active-layer depths and gas fluxes is also important in helping us to understand how increased fire frequency projected in future decades may impact on greenhouse gas emissions to the atmosphere. Our detailed measurements and process understanding will inform development of an integrated land surface-permafrost modelling system (JULES-SPA). This will allow improved simulation of permafrost biogeochemical cycles in Earth System models used for future climate projections. A second complementary research theme focuses long term changes in peatland permafrost over the Holocene based on model simulations.

Key staff: Julian Murton, Yi Wang

Carbon and forests

Carbon and forests. One of the great challenges in understanding the carbon cycle in forest ecosystems is how to measure key ecosystem variables over the large scales suitable for modelling global budgets.  Satellite and airborne Earth Observation instruments (e.g. see Hyspiri and Airmoss projects) provide a potential solution to this problem. Our approach is to develop methods to assimilate lidar, radar and hyperspectral data into the state-of-the-art Ecosystem Dynamics biosphere model to improve current and future estimates of carbon, water, and energy fluxes in forests.

Key staff: Alex Antonarakis

Example projects

  • CYCLOPS: Carbon cycling linkages to permafrost systems
  • HyspIRI preparatory mission: Hyperspectral imagery used in this project to provide accurate and comprehensive measurements of current ecosystem state in the form of plant functional types
  • AirMOSS: Airborne Monitoring of Subcanopy and Subsurface soil moisture. Development of regional scale Net Ecosystem Exchange (NEE) products using P-band Radar soil moisture and the ED2 terrestrial biosphere model

Selected publications

Antonarakis, A.S., Munger, J.W. and Moorcroft, P.R. (2014). Imaging spectroscopy- and lidar- derived estimates of canopy composition and structure to improve predictions of forest carbon fluxes and ecosystem dynamics. Geophysical Research Letters. 41, 2535–2542.

Antonarakis, A.S., Saatchi, S.S., Chazdon, R.L. and Moorcroft, P.R (2011) Using Lidar and Radar measurements to constrain predictions of forest ecosystem structure and function. Ecological Applications, 21 (4), 1120-1137.

Wang, Y, N. T. Roulet, S. Frolking, and L. A. Mysak (2009) The Importance of Northern Peatlands in Global Carbon Systems During the Holocene, Climate of the Past, 5, 683-693, doi:10.5194/cp-5-683-2009.

Wang, Y, N. T. Roulet, S. Frolking, L. A. Mysak, X. Liu and Z. Jin (2010) The First-Order Effect of Holocene Northern Peatlands on Global Carbon Cycle Dynamics, The open-access online journal IOP Conference Series: Earth and Environmental Science, 9, 012004, doi:10.1088/1755-1315/9/1/012004.