A statement by the deep-sea research community for consideration by UNFCCC

2 September 2015

A statement by the deep-sea research community for consideration by UNFCCC


The deep sea is an integral part of the earth system and plays a significant role in minimizing the impact of human released CO2 on the earth’s climate. The waters and seafloor below 200m are one of the largest sinks of excess carbon dioxide and heat and have already absorbed more than a quarter of anthropogenic atmospheric CO2. Ocean acidification, warming and deoxygenation resulting from human CO2 release has already been observed in deep waters and these impacts are projected to intensify in coming decades.

The deep sea, which accounts for 99% of the habitable volume of the planet, is recognized to be highly heterogeneous in space and time, comprised of many different ecosystems that provide key provisioning, supporting, regulating, and cultural services to the global population in addition to its role in the global carbon cycle and heat regulation. These services occur in waters both within and beyond national jurisdictions. For example, the regeneration of nutrients in the deep sea provides shallow-water ecosystems the ability to extract CO2 from the atmosphere and sustain productive, harvestable fish stocks. Deep-sea habitats are and will continue to be impacted by climate change due to the cumulative effect of different stressors on their biota, including expanding oxygen minimum zones, shoaling of aragonite saturation horizons, acidification and warming.

These climate-change impacts combine with direct human activities to create vulnerable deep-sea areas. It is crucial to incorporate climate change into holistic environmental planning in the deep ocean and to develop a global ‘deep’ observing network targeting ecosystems and regions at the nexus of climate change and deep-sea exploitation.

We the undersigned, encourage the UNFCCC to integrate the role of the deep ocean in its endeavors to mitigate climate change. There is a crucial and urgent need for a dedicated momentum supporting: 

  • Greater attention to the role of the deep ocean in mitigation and impact in ocean modeling and reporting.
  • Acknowledgement of the vulnerability and importance of the ocean and especially the deep ocean in negotiation text.
  • Direction of adaptation funding to deep-ocean observations, long-term integrated ecosystem and physiology studies critical to an accurate assessment of climate change scenarios and their impacts on deep-sea services.




While global seafloor exploration is progressively revealing the tremendous diversity and fragmentation of deep-sea ecosystems, their sensitivity to climate change is still largely unstudied. Not only the conservation of its unique biodiversity needs attention, but also the synergetic effects of climate change and increasing exploitation of resources (fishing, extraction of minerals and hydrocarbons) on deep-sea ecological functions and services.

Synergies accross marine and climate sciences, geosciences and economics have established new paradigms and confirmed the vulnerability of the deep-sea to climate change. Observations provides growing evidence of the influence of climatic forcing on ecosystems of the deep-seabed over many temporal scales (e.g. from storm events to climatic ocean oscillations), including numerous ecological hotspots such as seamounts, ridges and canyons. Significant climate-driven impacts on ocean biogeochemistry (deoxygenation, acidification, changes in organic carbon fluxes) are predicted from empirical models built on climatic scenarios.

Areas where enhanced vertical mixing of ocean waters conjugate with direct pressures of human activities (e.g. deep-sea mining, oil and gas extraction, deep-sea fishing), like seamounts, canyons, upwelling or polar regions, are also particularly sensitive to climatic effects. This justifies the need to consider climate change in environmental managment and conservation strategies.

This DOSI WG aims to provide a platform to centralize information about scenarios and observations elucidating the impact of climate change on deep-sea ecosystem and addressing cumulative pressures, in order to integrate this into   environmental impact assesment and managment plans and the identification  of Marine Protected Areas. It will also aim to identify high-vulnerability areas and foster interdisciplinary approaches to investigate how deep-sea ecosystems interact with climate on a functional basis, and ultimately provide experimental and theoretical support to predictive models for this overlooked but largest component of the Earth system.

WG activities:

  1. The new working group will form in September 2016, building on the COP21-related initiatives, creating linkages with deep observing systems,  and formulating sessions at international conferences to create an international network.   Initial activities will be developed at the DOSI meeting in Aveiro, 30 August 2015.


If you are interested in participating in the DOSI-Climate Change working group, please contact WG Leads Nadine Le Bris: lebris@obs-banyuls.fr & Lisa Levin: llevin@ucsd.edu