Raphael ThysThe Copernicus Marine Service provides information used to produce and evaluate ecological forecasts and long-term projections for ocean deoxygenation.
Source: IUCN, "Ocean deoxygenation: Everyone’s problem" report published December, 2019.
The report examines where the ocean currently stands in terms of ocean oxygen loss and how we, as a global community, must act in the face of worsening conditions. It was aptly published at the 2019 COP25, which focused on the integral role of the ocean in the Earth climate system. Ocean deoxygenation has already caused disruptions in ecosystems, changes in the carbon cycle, and the problem is projected to intensify in the coming years. Ocean deoxygenation (or loss dissolved oxygen the water) is a consequence of human generated greenhouse gasses. As oxygen is essential for life, this phenomenon poses a threat to aquatic life across the spectrum, as well as to the millions of people who depend on marine life for nutrition and livelihood. The full report, created by IUCN along with an array of international scientific experts, can be found here along with the press release and summary for decision-makers.
The report launch at the COP25 featured a diverse group of ocean champions who have long identified ocean deoxygenation as major threat both to the ocean and the Earth system as a whole. The speakers included: Peter Thomson (UN Special Envoy for the Ocean), Grethel Aguilar (Acting Director General IUCN), Helen Ågren (Sweden Ambassador for the Ocean), Prof. Dan Laffoley (Marine Vice-Chair for the IUCN’s World Commission on Protected Areas), Prof. John Baxter (Member of the IUCN’s World Commission on Protected Areas), Prof. Lisa Levin (Distinguished Professor of biological oceanography and marine ecology at the Scripps Institution of Oceanography) and Sylvia Earle (IUCN Patron of Nature).
“Ocean deoxygenation is one of the most pernicious, yet under-reported side-effects of human-induced climate change,” says the report. It describes the primary activators of ocean deoxygenation:
- Ocean warming because warmer water holds less (soluble) oxygen,
- Stratification as limited vertical mixing in the ocean reduces oxygen exchange between the ocean and the atmosphere,
- Eutrophication in coastal areas, resulting from increased river export of nitrogen and phosphorus, implies huge oxygen consumption, and when combined with a low ventilation, leads to the occurrence of oxygen deficiencies near the sea bed.
The report shows that the global ocean oxygen inventory has decreased by ~2% over the period 1960 to 2010. The IUCN report further states that ocean model simulations project a further decline in the dissolved oxygen inventory of the global ocean of 1 to 7% by the year 2100, caused by a combination of a warming-induced decline in oxygen solubility and reduced ventilation of the deep ocean. Ocean deoxygenation is closely related to ocean warming and ocean acidification caused by increasing carbon dioxide driven by anthropogenic (human) emissions, as well as biogeochemical consequences related to anthropogenic fertilization of the ocean (such as from land pollution run-off). A joint and multi-disciplinary combined effort investigating the different stressors will be most beneficial to understand future ocean changes.
Marilaure Grégoire from University of Liège in Belgium is the lead author of Chapter 1 “What is ocean deoxygenation?”. She stresses “the importance of the Copernicus Marine Service for delivering high-quality forecasts of low oxygen zones to support the decision making process. Long-term projections are also essential for projecting ocean deoxygenation at the 2100 horizon and its consequences on the global biogeochemical cycles of carbon, nitrogen and phosphorus.”
In the Copernicus context, she leads the Copernicus Marine Service Black Sea Biogeochemistry Monitoring and Forecasting Center (Black Sea MFC) and is a member of the Copernicus Marine Scientific and Technical Advisory Committee- STAC). The Copernicus Marine Service is one of the international platforms that provides essential data that is used to produce and evaluate ecological forecasts for ocean deoxygenation. The Ocean State Report 2 for example highlights the deoxygenation in the Black Sea.
Figure: Copernicus Marine Ocean State Report 2 Summary
IUCN report bolsters and adds even more urgency to the findings in the September 2019 United Nations Special Report on the Ocean and Cryosphere in a Changing Climate (IPCC SROCC). It asserted that ocean oxygen loss is primarily due to increasing ocean stratification and impacts marine ventilation and biogeochemistry (high confidence). It projects that oxygen loss between 100 and 600 metres depth is projected to emerge over 59–80% of the ocean area by 2031–2050 under RCP8.5 (very likely).
Source: Ocean Oxygen in the past and future changes in the UN Special Report on the Ocean and Cryosphere in a Changing Climate (IPCC SROCC) published in September 2019.
