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The Sensitivity of Future Ocean Oxygen to Changes in Ocean Circulation

Abstract.

"A decline in global ocean oxygen concentrations has been observed over the twentieth century and is predicted to continue under future climate change. We use a unique modeling framework to understand how the perturbed ocean circulation may influence the rate of ocean deoxygenation in response to a doubling of atmospheric CO2 and associated global warming. [...]"

Source: Global Biogeochemical Cycles
Authors: Jaime B. Palter and David S. Trossman
DOI: 10.1002/2017GB005777

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Powering Ocean Giants: The Energetics of Shark and Ray Megafauna

Abstract.

"Energetics studies have illuminated how animals partition energy among essential life processes and survive in extreme environments or with unusual lifestyles. There are few bioenergetics measurements for elasmobranch megafauna; the heaviest elasmobranch for which metabolic rate has been measured is only 47.7 kg, despite many weighing >1000 kg. Bioenergetics models of elasmobranch megafauna would answer fundamental ecological questions surrounding this important and vulnerable group, and enable an understanding of how they may respond to changing environmental conditions, such as ocean warming and deoxygenation. [...]"

Source: Trends in Ecology & Evolution
Authors: Christopher L. Lawson et al.
DOI: 10.1016/j.tree.2019.07.001

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Variations in ocean deoxygenation across Earth System Models: Isolating the role of parametrized lateral mixing

Abstract.

"Modern Earth System Models (ESMs) disagree on the impacts of anthropogenic global warming on the distribution of oxygen and associated low‐oxygen waters. A sensitivity study using the GFDL CM2Mc model points to the representation of lateral mesoscale eddy transport as a potentially important factor in such disagreement. Because mesoscale eddies are smaller than the spatial scale of ESM ocean grids, their impact must be parameterized using a lateral mixing coefficient AREDI. [...]"

Source: Global Biogeochemical Cycles
Authors: A. Bahl, A. Gnanadesikan and M.‐A. Pradal
DOI: 10.1029/2018GB006121

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Strong intensification of the Arabian Sea oxygen minimum zone in response to Arabian Gulf warming

Abstract.

"The highly saline, oxygen saturated waters of the Arabian Gulf (hereafter the Gulf) sink to intermediate depths (200‐300m) when they enter the Arabian Sea, ventilating the World's thickest oxygen minimum zone (OMZ). Here, we investigate the impacts of a warming of the Gulf consistent with climate change projections on the intensity of this OMZ. Using a series of eddy‐resolving model simulations, we show that the warming of the Gulf waters increases their buoyancy and hence limits their contribution to the ventilation of intermediate depths. [...]"

Source: Geophysical Research Letters
Authors: Z. Lachkar, M. Lévy and S. Smith
DOI: 10.1029/2018GL081631

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As oceans warm, microbes could pump more CO2 back into air, study warns

"The world's oceans soak up about a quarter of the carbon dioxide that humans pump into the air each year -- a powerful brake on the greenhouse effect. In addition to purely physical and chemical processes, a large part of this is taken up by photosynthetic plankton as they incorporate carbon into their bodies. When plankton die, they sink, taking the carbon with them. Some part of this organic rain will end up locked into the deep ocean, insulated from the atmosphere for centuries or more. [...]"

Source: EurekAlert!

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Assessment of time of emergence of anthropogenic deoxygenation and warming: insights from a CESM simulation from 850 to 2100 CE

Abstract.

"Marine deoxygenation and anthropogenic ocean warming are observed and projected to intensify in the future. These changes potentially impact the functions and services of marine ecosystems. A key question is whether marine ecosystems are already or will soon be exposed to environmental conditions not experienced during the last millennium. Using a forced simulation with the Community Earth System Model (CESM) over the period 850 to 2100, we find that anthropogenic deoxygenation and warming in the thermocline exceeded natural variability in, respectively, 60 % and 90 % of total ocean area. [...]"

Source: Biogeosciences
Authors: Angélique Hameau, Juliette Mignot Fortunat Joos
DOI: 10.5194/bg-16-1755-2019

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Much of the surface ocean will shift in color by end of 21st century

"Climate change is causing significant changes to phytoplankton in the world's oceans, and a new MIT study finds that over the coming decades these changes will affect the ocean's color, intensifying its blue regions and its green ones. Satellites should detect these changes in hue, providing early warning of wide-scale changes to marine ecosystems. [...]"

Source: ScienceDaily

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Ocean colour signature of climate change

Abstract.

"Marine calcifiers are considered to be among the most vulnerable taxa to climate-forced environmental changes occurring on continental margins with effects hypothesized to occur on microstructural, biomechanical, and geochemical properties of carbonate structures. Natural gradients in temperature, salinity, oxygen, and pH on an upwelling margin combined with the broad depth distribution (100–1,100 m) of the pink fragile sea urchin, Strongylocentrotus (formerly Allocentrotus) fragilis, along the southern California shelf and slope provide an ideal system to evaluate potential effects of multiple climate variables on carbonate structures in situ. [...]"

Source: Nature Communications
Authors: Stephanie Dutkiewicz et al.
DOI: 10.1038/s41467-019-08457-x

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Asymmetric dynamical ocean responses in warming icehouse and cooling greenhouse climates

Abstract.

"Warm periods in Earth's history tend to cool more slowly than cool periods warm. Here we explore initial differences in how the global ocean takes up and gives up heat and carbon in forced rapid warming and cooling climate scenarios. We force an intermediate-complexity earth system model using two atmospheric CO2 scenarios. A ramp-up (1% per year increase in atmospheric CO2 for 150 years) starts from an average global CO2 concentration of 285 ppm to represent warming of an icehouse climate. [...]"

Source: Environmental Research Letters
Authors: Karin F. Kvale et al.
DOI: 10.1088/1748-9326/aaedc3

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How fast are the oceans warming?

Abstract.

"Climate change from human activities mainly results from the energy imbalance in Earth's climate system caused by rising concentrations of heat-trapping gases. About 93% of the energy imbalance accumulates in the ocean as increased ocean heat content (OHC). The ocean record of this imbalance is much less affected by internal variability and is thus better suited for detecting and attributing human influences than more commonly used surface temperature records. Recent observation-based estimates show rapid warming of Earth's oceans over the past few decades (see the figure). [...]"

Source: Science
Authors: Lijing Cheng et al
DOI: 10.1126/science.aav7619

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