Water stored in and released from supraglacial lakes is an important factor when considering the seasonal and long-term evolution of the Greenland ice sheet. Here we use a radiative transfer model to estimate changes in the depth and volume of a supraglacial lake on the surface of Jakobshavn Isbræ, West Greenland, between 2002 and 2005. When compared to estimates of the lake depth determined from airborne lidar observations, we estimate that the root-mean-square departure of the modelled lake depths was 0.3 m during cloud-free conditions. The maximum lake area, depth and volume were 3.4 km2, 9.6 ±1.0 m and (18.6±3.7)×106 m3, respectively. When sequenced according to the number of positive degree-days (PDDs) accumulated prior to each image, we observe that the lake volume evolves in three distinct phases. At the start of the melting season, the rate of filling is slow; after approximately 80 PDDs the rate of filling increases by a factor ∽3, and after approximately 125 PDDs the lake drains rapidly. We estimate that the lake drains at a minimum rate of (2.66±0.53)×106 m3 d–1 over a 6 day period.

The Cuvette Centrale is the largest tropical peatland complex in the world, covering approximately 145,000 km2 across the Republic of Congo and the Democratic Republic of Congo. It stores ca. 30.6 Pg C, the equivalent of three years of global carbon dioxide emissions and is now the first trans-national Ramsar site. Despite its size and importance as a global carbon store, relatively little is known about key aspects of its ecology and history, including its formation, the scale of greenhouse gas flows, its biodiversity and its history of human activity. Here, we synthesise available knowledge on the Cuvette Centrale, identifying key areas for further research. Finally, we review the potential of mathematical models to assess future trajectories for the peatlands in terms of the potential impacts of resource extraction or climate change.

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La Cuvette centrale est le plus vaste complexe de tourbières tropicales au monde, qui s'étend sur environ 145 000 km2 en République du Congo et en République démocratique du Congo. Ce complexe stocke environ 30,6 Pg C, soit l'équivalent de trois années d'émissions mondiales de dioxyde de carbone, et représente désormais le premier site Ramsar transnational. Malgré sa taille et son importance mondiale en tant que puits de carbone, les aspects clés de son écologie et de son histoire, notamment sa formation, l'ampleur des flux de gaz à effet de serre, sa biodiversité et l'histoire de l'activité humaine, demeurent relativement peu connus. Nous synthétisons ici les connaissances disponibles sur la Cuvette centrale, en identifiant des domaines clés pour la poursuite des recherches. Enfin, nous examinons le potentiel des modèles mathématiques pour évaluer les trajectoires futures des tourbières en termes d’impacts prévisibles de l'exploitation de ressources et du changement climatique.

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