Changing Arctic Carbon cycle in the cOastal Ocean Near-shore - CACOON

CACOON is part of a research project network on the topic "Changing Arctic Ocean". Hardly any other region warmed as much in the past decades as the Arctic. The aim of the projects is to investigate the influence of this warming on the global climate and on the communities in the polar region. CACOON, funded by the German Federal Ministry of Education and Research (BMBF) and the British Natural Environment Research Council (NERC) helps to better understand – and predict – changes to the Arctic marine environment and ecosystems.

CACOON Background

Arctic rivers annually carry around 13% of all dissolved organic carbon transported globally from land to ocean, despite the Arctic Ocean (AO) making up only approximately 1% of the total Earths ocean volume. Arctic shelf waters are therefore dominated by terrestrial carbon pools, and their physical and biological processes intimately linked to freshwater supplies. Arctic terrestrial ecosystems contain vast quantities of frozen carbon locked up underground, known as permafrost. These permafrost deposits represent one of the largest climate-vulnerable carbon pools globally, due to its susceptibility to thaw and mobilisation offshore in response to Arctic climate warming.

Rapid climate change is already resulting in permafrost thaw, sea-ice reduction and increasing riverine discharge over much of the pan-Arctic, triggering important feedbacks between terrestrial ecosystems and the AO. The importance of the entire near-shore region, consisting of several tightly connected ecosystems that include rivers, deltas, estuaries and the continental shelf, is however often overlooked and currently poorly understood. Seasonally-explicit studies are lacking severely limiting our ability to predict the impact of shifting seasonality, and of fresher waters, more concentrated nutrients and greater proportions of permafrost-derived carbon on coastal water processes and feedbacks. CACOON aims to address this knowledge gap by detailed investigations of the near-shore regions of the two major Arctic Lena and Kolyma rivers which combined cover 19% of the entire pan-Arctic watershed area contributing to the AO.


CACOON will quantify the effect of changing freshwater export and terrestrial permafrost thaw on the type and fate of river-borne organic matter (OM) delivered to Arctic coastal waters, and resultant changes on ecosystem functioning in the coastal AO. We will achieve this though a combined observational, experimental and modelling study. We will conduct laboratory experiments to parameterise the susceptibility of terrigenous carbon to abiotic and biotic transformation and losses, then use the results from these to deliver a marine ecosystem model capable of representing the major biogeochemical cycles of carbon, nutrients and OM cycling in these regions. We will apply this model to assess how future changes to freshwater runoff and terrigenous carbon fluxes alter the biogeochemical structure and function of shelf ecosystems.

CACOON is an international project including project partners in Germany, UK, USA, Russia and Norway.

Project Information

ContactJens Strauss
Project Duration
01.07.2018 -30.06.2021

co funded by

German Federal Ministry of Education and Research

Natural Environment Research Council (NERC)

Funding Recipients

Jens Strauss

Paul J. Mann

Participants (AWI)

Gesine Mollenhauer
Guido Grosse
Paul Overduin
Olga Ogneva

Participants (extern)

Paul J. Mann (Northumbria University, UK)

Luca Polimene (Plymouth Marine Laboratory, UK)

Ricardo Tores (Plymouth Marine Laboratory, UK)

Section (AWI)

Permafrost Research

Marine Geochemistry