The evolving response of mesopelagic fishes to declining midwater oxygen concentrations in the southern and central California Current
"Declining oxygen concentrations in the deep ocean, particularly in areas with pronounced oxygen minimum zones (OMZs), are a growing global concern related to global climate change. Its potential impacts on marine life remain poorly understood. A previous study suggested that the abundance of a diverse suite of mesopelagic fishes off southern California was closely linked to trends in midwater oxygen concentration. [...]"
Source: ICES Journal of Marine Science
Authors: J Anthony Koslow et al.
Why Is the Gulf of Maine Warming Faster Than 99% of the Ocean?
"The Gulf of Maine’s location at the meeting point of two major currents, as well as its shallow depth and shape, makes it especially susceptible to warming.
Late last month, four endangered sea turtles washed ashore in northern Cape Cod, marking an early onset to what has now become a yearly event: the sea turtle stranding season. These turtles—in last month’s case, Kemp’s ridley sea turtles—venture into the Gulf of Maine during warm months, but they can become hypothermic and slow moving when colder winter waters abruptly arrive, making it hard to escape. “They are enjoying the warm water, and then all of a sudden the cold comes, and they can’t get out fast enough,” said Andrew Pershing, an oceanographer at the Gulf of Maine Research Institute in Portland, Maine. [...]"
Volcanic eruptions once caused mass extinctions in the oceans – could climate change do the same?
This process has the potential to disrupt marine food chains. We already know that large hypoxic, or low-oxygen, zones can be deadly. If hypoxia expands in both size and duration, it is possible to cause widespread extinction of marine life, which has happened previously in Earth’s history. [...]"
The Oceans Are Warming Even Faster Than We Previously Thought
"The oceans have long been considered our planet's heat sponge - a 2014 report from the Intergovernmental Panel on Climate Change (IPCC) stated that the oceans had absorbed 93% of the excess heat that greenhouse gases have trapped within the Earth's atmosphere. However, a recent study shows that the world's oceans have absorbed 60% more heat over the past 25 years than initially thought. [...]"
Author: Priya Shukla
Forcings and Evolution of the 2017 Coastal El Niño Off Northern Peru and Ecuador
"El Niño events, in particular the eastern Pacific type, have a tremendous impact on the marine ecosystem and climate conditions in the eastern South Pacific. During such events, the accumulation of anomalously warm waters along the coast favors intense rainfall. The upwelling of nutrient-replete waters is stopped and the marine ecosystem is strongly impacted. These events are generally associated with positive surface temperature anomalies in the central and eastern equatorial Pacific. [...]"
Source: Frontiers in Marine Science
Authors: Vincent Echevin et al.
Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composition
"The ocean is the main source of thermal inertia in the climate system. During recent decades, ocean heat uptake has been quantified by using hydrographic temperature measurements and data from the Argo float program, which expanded its coverage after 2007. However, these estimates all use the same imperfect ocean dataset and share additional uncertainties resulting from sparse coverage, especially before 2007. [...]"
Authors: L. Resplandy et al.
Oysters as sentinels of climate variability and climate change in coastal ecosystems
"Beyond key ecological services, marine resources are crucial for human food security and socio-economical sustainability. Among them, shellfish aquaculture and fishing are of primary importance but become more vulnerable under anthropogenic pressure, as evidenced by reported mass mortality events linked to global changes such as ocean warming and acidification, chemical contamination, and diseases. Understanding climate-related risks is a vital objective for conservation strategies, ecosystems management and human health. [...]"
Source: Environmental Research Letters
Authors: Yoann Thomas et al.
Projected Centennial Oxygen Trends and Their Attribution to Distinct Ocean Climate Forcings
"We explore centennial changes in tropical Pacific oxygen (O2) using numerical models to illustrate the dominant patterns and mechanisms under centennial climate change. Future projections from state‐of‐the‐art Earth System Models exhibit significant model to model differences, but decreased solubility and weakened ventilation together deplete thermocline O2 in middle to high latitudes. In contrast, the tropical thermocline O2undergoes much smaller changes or even a slight increase. [...]"
Source: Global Biogeochemical Cycles
Authors: Yohei Takano, Takamitsu Ito & Curtis Deutsch
Shift in large-scale Atlantic circulation causes lower-oxygen water to invade Canada’s Gulf of St. Lawrence
"The Gulf of St. Lawrence has warmed and lost oxygen faster than almost anywhere else in the global oceans. The broad, biologically rich waterway in Eastern Canada drains North America’s Great Lakes and is popular with fishing boats, whales and tourists.
A new study led by the University of Washington looks at the causes of this rapid deoxygenation and links it to two of the ocean’s most powerful currents: the Gulf Stream and the Labrador Current. The study, published Sept. 17 in Nature Climate Change, explains how large-scale climate change already is causing oxygen levels to drop in the deeper parts of this waterway."
Source: University of Washington
Author: Hannah Hickey
Identifying oxygen minimum zone-type biogeochemical cycling in Earth history using inorganic geochemical proxies
"Because of anthropogenic global warming, the world ocean is currently losing oxygen. This trend called ocean deoxygenation is particularly pronounced in low-latitude upwelling-related oxygen minimum zones (OMZs). In these areas, the temperature-related oxygen drawdown is additionally modulated by biogeochemical feedback mechanisms between sedimentary iron (Fe) and phosphorus release, water column nitrogen cycling and primary productivity. Similar feedbacks were likely active during past periods of global warming and oceandeoxygenation. However, their integrated role in amplifying or mitigating climate change-driven ocean anoxia has not been evaluated in a systematic fashion. [...]"
Source: Earth-Science Reviews
Author: Florian Scholz