News

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. [...]"

Source: Forbes
Author: Priya Shukla

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Forcings and Evolution of the 2017 Coastal El Niño Off Northern Peru and Ecuador

Abstract.

"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.
DOI: 10.3389/fmars.2018.00367

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Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composition

Abstract.

"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.  [...]"

Source: Nature
Authors: L. Resplandy et al.
DOI: 10.1038/s41586-018-0651-8

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Oysters as sentinels of climate variability and climate change in coastal ecosystems

Abstract.

"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.
DOI: 10.1088/1748-9326/aae254

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Projected Centennial Oxygen Trends and Their Attribution to Distinct Ocean Climate Forcings

Abstract.

"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
DOI: 10.1029/2018GB005939

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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

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Identifying oxygen minimum zone-type biogeochemical cycling in Earth history using inorganic geochemical proxies

Abstract.

"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
DOI: 10.1016/j.earscirev.2018.08.002

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Large-scale ocean deoxygenation during the Paleocene-Eocene Thermal Maximum

Abstract.

"The consequences of global warming for fisheries are not well understood, but the geological record demonstrates that carbon cycle perturbations are frequently associated with ocean deoxygenation. Of particular interest is the Paleocene-Eocene Thermal Maximum (PETM), where the carbon dioxide input into the atmosphere was similar to the IPCC RCP8.5 emission scenario. Here we present sulfur-isotope data that record a positive 1 per mil excursion during the PETM. Modeling suggests that large parts of the ocean must have become sulfidic. [...]"

Source:Science
Authors: Weiqi Yao, Adina Paytan, Ulrich G. Wortmann
DOI: 10.1126/science.aar8658

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Increased biofilm formation due to high-temperature adaptation in marine Roseobacter

Abstract.

"Ocean temperatures will increase significantly over the next 100 years due to global climate change. As temperatures increase beyond current ranges, it is unclear how adaptation will impact the distribution and ecological role of marine microorganisms. To address this major unknown, we imposed a stressful high-temperature regime for 500 generations on a strain from the abundant marine Roseobacter clade. High-temperature-adapted isolates significantly improved their fitness but also increased biofilm formation at the air–liquid interface.  [...]"

Source: Nature Microbiology
Authors: Alyssa G. Kent et al.
DOI: 10.1038/s41564-018-0213-8

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Scientists draw new connections between climate change and warming oceans

"Earth scientists exploring how ocean chemistry has evolved found similarities between an event 55 million years ago and current predicted trajectories of planet temperatures, with regards to inputs of CO2 into the atmosphere and oxygen levels in the oceans. As the oceans warm, oxygen decreases while hydrogen sulfide increases, making the oceans toxic and putting marine species at risk."

Source: Science Daily (University of Toronto)

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