Carbon-cycle dynamics in the Congo Basin today and through time

Prof. Dr. Jordon Hemingway, ETH Zürich

Abstract

The Congo Basin contains the world’s second largest rainforest and the largest tropical peatland complex, which stores ~30 GtC as peat organic carbon. Additionally, these peatlands drain into several massive humic (i.e., acidic, organic-rich) lakes, which likely act as “hot spots” of carbon exchange between the landscape and the atmosphere. Despite this importance, our understanding of carbon-cycle dynamics—particularly greenhouse gas emissions—from the Congo Basin in general and from humic lakes in particular is hindered by a lack of observational constraints. Here, I will discuss emitted greenhouse gas flux and source estimates from a series of field campaigns conducted between 2022 and 2025. Results indicate that up to one third of carbon dioxide emitted from humic lakes is derived from the degradation and sub-surface transport of ancient peat organic carbon, a previously overlooked processes. I will then highlight changes in climate and landscape vegetation cover over the past ~5,000 years as recorded in sediments of these lakes and discuss how such variability may have impacted carbon cycling in the past and could act as an analog for future perturbations.