Biogeochemistry seminars

Christopher R. German examines how hydrothermal circulation affects basin-scale ocean biogeochemical cycles. Early global surveys preceded the discovery of seafloor vents, and hydrothermal inputs were long considered minor and local. GEOTRACES sections and subsequent process studies have transformed that view; the presentation traces how those observations changed understanding of trace-element and isotope cycling. Laura Moore discusses the biogeochemical consequences of widespread low-temperature hydrothermal flow, highlighting advances in detection and the distinctive effects of these systems on the water column. Lise Artigue moderates this sixth seminar of the 2026 GEOTRACES online series. Attend online via the GEOTRACES recurring public Zoom meeting. The seminar begins at 15:00 CET.

Reducing greenhouse-gas emissions alone does not remove the excess carbon dioxide already present in the atmosphere. This talk surveys marine carbon dioxide removal approaches that use the ocean’s capacity to absorb CO₂ and explains instrumentation for evaluating their effectiveness. David Snyder describes DeepGreen Solutions’ Carbon Ocean-Based Atmospheric Linked Telemetry (COBALT) measurement system, which combines sensors on Sofar Ocean Spotter buoys and Spotter Scout autonomous surface vessels to investigate carbon-cycle processes and the atmospheric removal achieved by marine projects. The session includes questions and discussion.

Jérôme Chave examines how tropical forests respond to warming and rising carbon dioxide. Their carbon uptake is constrained by physiology, ecological interactions and extreme conditions. Long-term field observations, analytical methods and models are used to investigate future carbon storage, biodiversity and the persistence of forest communities under global change.

This lecture examines how fossil-carbon emissions disturb exchanges among the atmosphere, vegetation, soils and oceans. Natural sinks currently limit atmospheric carbon accumulation, but wildfire, forest decline and other climate feedbacks could weaken that buffering. Satellite observations of vegetation and greenhouse gases help constrain exchanges, while uncertain feedbacks remain important limitations for projections.