Monitoring ocean biogeochemistry with autonomous platforms
"Human activities have altered the state of the ocean, leading to warming, acidification and deoxygenation. These changes impact ocean biogeochemistry and influence ecosystem functions and ocean health. The long-term global effects of these changes are difficult to predict using current satellite sensing and traditional in situ observation techniques. [...]"
Source: Nature Reviews Earth & Environment
Authors: Fei Chai et al.
Twenty-first century ocean warming, acidification, deoxygenation, and upper-ocean nutrient and primary production decline from CMIP6 model projections
"Anthropogenic climate change is projected to lead to ocean warming, acidification, deoxygenation, reductions in near-surface nutrients, and changes to primary production, all of which are expected to affect marine ecosystems. Here we assess projections of these drivers of environmental change over the twenty-first century from Earth system models (ESMs) participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6) that were forced under the CMIP6 Shared Socioeconomic Pathways (SSPs). [...]"
Authors: Lester Kwiatkowski et al.
How ocean deoxygenation enters the global agenda
A Story of the Collaborative Research Centre "Climate-Biogeochemistry Interactions in the Tropical Ocean"
After 12 years of intensive research, the Collaborative Research Centre 754 "Climate-Biogeochemical Interactions in the Tropical Ocean" ended in winter 2019 with a final symposium in Heiligenhafen.
More than 100 scientists involved in the large-scale project over its entire running time were able to gain numerous new insights into the processes of nutrient cycling, the interaction between ocean and atmosphere and the ecosystems in the tropical oceans. Above all, however, they drew attention to a phenomenon that affects the entire ocean: global oxygen loss and the spread of oxygen minimum zones in the ocean. With this video, the SFB 754 now draws a conclusion and at the same time points out the new research tasks that have resulted from its work. These include improved ocean observation and the question of how to prevent further oxygen loss.
For more information please look at www.sfb754.de
For a german version of the video please follow this link.
Additive impacts of deoxygenation and acidification threaten marine biota
"Deoxygenation in coastal and open‐ocean ecosystems rarely exists in isolation but occurs concomitantly with acidification. Here, we first combine meta‐data of experimental assessments from across the globe to investigate the potential interactive impacts of deoxygenation and acidification on a broad range of marine taxa. [...]"
Source: Global Change Biology
Authors: Alexandra Steckbauer et al.
Reconstructing N2-fixing cyanobacterial blooms in the Baltic Sea
beyond observations using 6- and 7-methylheptadecane in sediments as specific biomarkers
"Summer cyanobacterial blooms represent a threat to the Baltic Sea ecosystem, causing deoxygenation of the bottom water and the spread of the so-called dead zones. The history of the Baltic Sea cyanobacterial blooms is known from in situ and satellite observations since the early 1980s but is still not well understood. [...]"
Authors: Jérôme Kaiser et al.
A revisit to the regulation of oxygen minimum zone in the Bay of Bengal
"Occurrence of intense oxygen minimum zone (OMZ) is known in the Bay of Bengal (BoB), but it has been recently reported to have become more acute and is at its tipping point. Here, we show that the intensification of OMZ to acute condition is a random and short-term rather than perennial phenomenon based on re-evaluation of old and recent information in the BoB. Short-term modifications in dissolved oxygen (DO) in the OMZ are caused by balance among physical forcings: salinity stratification, occurrence of cyclonic (CE), and anticyclonic eddies (ACE). [...]"
Source: Journal of Earth System Science
Authors: B Sridevi and V V S S Sarma
Ocean deoxygenation could be silently killing coral reefs, scientists say
The cause of this bleaching event was climate change, which brought unusually warm waters to the Great Barrier Reef in February, and disrupted the delicate, symbiotic relationship between the corals and their life-sustaining algae. In general, when sea temperatures rise, corals become stressed and expel algae from their tissues. Without this algae, the corals turn ghostly white and slowly starve. [...]"
'A bad time to be alive': Study links ocean deoxygenation to ancient die-off
"In a new study, Stanford researchers have strongly bolstered the theory that a lack of oxygen in Earth's oceans contributed to a devastating die-off approximately 444 million years ago. The new results further indicate that these anoxic (little- to no-oxygen) conditions lasted over 3 million years—significantly longer than similar biodiversity-crushing spells in our planet's history. Beyond deepening understandings of ancient mass extinction events, the findings have relevance for today: Global climate change is contributing to declining oxygen levels in the open ocean and coastal waters, a process that likely spells doom for a variety of species. [...]"
Is deoxygenation detectable before warming in the thermocline?
"Anthropogenic greenhouse gas emissions cause ocean warming and oxygen depletion, with adverse impacts on marine organisms and ecosystems. Warming is one of the main indicators of anthropogenic climate change, but, in the thermocline, changes in oxygen and other biogeochemical tracers may emerge from the bounds of natural variability prior to warming. Here, we assess the time of emergence (ToE) of anthropogenic change in thermocline temperature and thermocline oxygen within an ensemble of Earth system model simulations from the fifth phase of the Coupled Model Intercomparison Project. [...]"
Authors: Angélique Hameau et al.
Coral reef survival under accelerating ocean deoxygenation
"Global warming and local eutrophication simultaneously lower oxygen (O2) saturation and increase biological O2 demands to cause deoxygenation. Tropical shallow waters, and their coral reefs, are particularly vulnerable to extreme low O2 (hypoxia) events. These events can drive mass mortality of reef biota; however, they currently remain unaccounted for when considering coral reef persistence under local environmental alterations and global climatic change. [...]"
Source: Nature Climate Change
Authors: David J. Hughes et al.