News

Simulations of ocean deoxygenation in the historical era: insights from forced and coupled models

Abstract.

"Ocean deoxygenation due to anthropogenic warming represents a major threat to marine ecosystems and fisheries. Challenges remain in simulating the modern observed changes in the dissolved oxygen (O2). Here, we present an analysis of upper ocean (0-700m) deoxygenation in recent decades from a suite of the Coupled Model Intercomparison Project phase 6 (CMIP6) ocean biogeochemical simulations. The physics and biogeochemical simulations include both ocean-only (the Ocean Model Intercomparison Project Phase 1 and 2, OMIP1 and OMIP2) and coupled Earth system (CMIP6 Historical) configurations. [...]".

 

Source: Frontiers in Marine Science 
Authors: Yohei Takano et al.
DOI: https://doi.org/10.3389/fmars.2023.1139917

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Impact of deoxygenation and warming on global marine species in the 21st century

Abstract.

"Ocean temperature and dissolved oxygen shape marine habitats in an interplay with species' physiological characteristics. Therefore, the observed and projected warming and deoxygenation of the world's oceans in the 21st century may strongly affect species' habitats. Here, we implement an extended version of the Aerobic Growth Index (AGI), which quantifies whether a viable population of a species can be sustained in a particular location. We assess the impact of projected deoxygenation and warming on the contemporary habitat of 47 representative marine species covering the epipelagic, mesopelagic, and demersal realms. [...]".

 

Source: Biogeosciences
Authors: Anne L. Morée et al.
DOI: https://doi.org/10.5194/bg-20-2425-2023

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Increasing hypoxia on global coral reefs under ocean warming

Abstract. 

"Ocean deoxygenation is predicted to threaten marine ecosystems globally. However, current and future oxygen concentrations and the occurrence of hypoxic events on coral reefs remain underexplored. Here, using autonomous sensor data to explore oxygen variability and hypoxia exposure at 32 representative reef sites, we reveal that hypoxia is already pervasive on many reefs. Eighty-four percent of reefs experienced weak to moderate (≤153 µmol O2 kg−1to ≤92 µmol O2 kg−1) hypoxia and 13% experienced severe (≤61 µmol O2 kg−1) hypoxia. Under different climate change scenarios based on four Shared Socioeconomic Pathways (SSPs) [...]".

 

Source: Nature 
Authors: Ariel K. Pezner et al.
DOI: https://doi.org/10.1038/s41558-023-01619-2

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A molecular perspective on the invasibility of the southern ocean benthos: The impact of hypoxia and temperature on gene expression

Abstract. 

"When an organism makes a long-distance transition to a new habitat, the associated environmental change is often marked and requires physiological plasticity of larvae, juveniles, or other migrant stages. Exposing shallow-water marine bivalves (Aequiyoldia cf. eightsii) from southern South America (SSA) and the West Antarctic Peninsula (WAP) to changes in temperature and oxygen availability, we investigated changes in gene expression in a simulated colonization experiment of the shores of a new continent after crossing of the Drake Passage, and in a warming scenario in the WAP. [...]".

 

Source: Frontiers
Authors: Mariano Martínez et al.
DOI: https://doi.org/10.3389/fphys.2023.1083240

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Warming, Acidification and Deoxygenation of the Ocean

Abstract. 

"The ocean plays an essential role in regulating Earth’s climate. The ocean provides many services, but two crucial ones are its ability to take up heat and carbon dioxide (CO2) from the atmosphere and cycle both around the world in its vast currents, as well as store them away long term. The ocean is changing rapidly and often unnoticed by the general public. However, as the effects of climate change become more prevalent on the ocean, we will start to see a direct impact on human society. This chapter discusses three main climate change effects on the ocean: ocean warming, acidification, and loss of oxygen. [...]".

 

Source: Springer Nature
Authors: Helen S. Findlay
DOI: https://doi.org/10.1007/978-3-031-10812-9_2

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Diverging Fates of the Pacific Ocean Oxygen Minimum Zone and Its Core in a Warming World

Abstract. 

"Global ocean oxygen loss is projected to persist in the future, but Earth system models (ESMs) have not yet provided a consistent picture of how it will influence the largest oxygen minimum zone (OMZ) in the tropical Pacific. We examine the change in the Pacific OMZ volume in an ensemble of ESMs from the CMIP6 archive, considering a broad range of oxygen (O2) thresholds relevant to biogeochemical cycles and ecosystems (5–160 µmol/kg). Despite OMZ biases in the historical period of the simulations, the ESM ensemble projections consistently fall into three regimes across ESMs […]".

 

Source: Wiley Online Library
Authors: Julius J.M. Busecke et al.
DOI: https://doi.org/10.1029/2021AV000470

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Investigating ocean deoxygenation and the oxygen minimum zone in the Central Indo Pacific region based on the hindcast datasets

Abstract. 

"Deoxygenation is increasingly recognized as a significant environmental threat to the ocean following sea temperature rises due to global warming and climate change. Considering the cruciality of the deoxygenation impacts, it is important to assess the current status and predict the future possibility of ocean deoxygenation, for instance, within the Central Indo Pacific (CIP) regions represent climate-regulated marine areas. This study divided CIP into five regions then investigated the deoxygenation parameters (dissolved oxygen, temperature, salinity, and pH) collected from 1993 to 2021 sourced from in situ measurement and long-term hindcast data. [...]".

 

Source: Environmental Monitoring and Assessment
Authors: Karlina Triana et al.
DOI: https://doi.org/10.1007/s10661-022-10615-6

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Impact of warming and deoxygenation on the habitat distribution of Pacific halibut in the Northeast Pacific

Abstract. 

"Ocean warming and deoxygenation are already modifying the habitats of many aerobic organisms. Benthic habitat in the Northeast Pacific is sensitive to deoxygenation, as low oxygen concentrations occur naturally in continental shelf bottom waters. Here, we examine the potential impacts of deoxygenation and ocean warming on the habitat distribution of Pacific halibut (Hippoglossus stenolepis), one of the most commercially important groundfish in North America. [...]".

 

Source: Wiley Online Library  
Authors: Ana C. Franco et al.
DOI: https://doi.org/10.1111/fog.12610

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Marine anoxia linked to abrupt global warming during Earth’s penultimate icehouse

Abstract.

"Piecing together the history of carbon (C) perturbation events throughout Earth’s history has provided key insights into how the Earth system responds to abrupt warming. Previous studies, however, focused on short-term warming events that were superimposed on longer-term greenhouse climate states. Here, we present an integrated proxy (C and uranium [U] isotopes and paleo CO2) and multicomponent modeling approach to investigate an abrupt C perturbation and global warming event (∼304 Ma) that occurred during a paleo-glacial state. We report pronounced negative C and U isotopic excursions coincident with a doubling of atmospheric CO2 partial pressure and a biodiversity nadir. [...]".

 

Source: Proceedings of the National Academy of Sciences
Authors: Jitao Chen et al.
DOI: https://doi.org/10.1073/pnas.2115231119

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A committed fourfold increase in ocean oxygen loss

Abstract.

"Less than a quarter of ocean deoxygenation that will ultimately be caused by historical CO2 emissions is already realized, according to millennial-scale model simulations that assume zero CO2 emissions from year 2021 onwards. About 80% of the committed oxygen loss occurs below 2000 m depth, where a more sluggish overturning circulation will increase water residence times and accumulation of respiratory oxygen demand. According to the model results, the deep ocean will thereby lose more than 10% of its pre-industrial oxygen content even if CO2 emissions and thus global warming[...]".

 

Source: Nature Communications
Authors: Andreas Oschlies
DOI: https://doi.org/10.1038/s41467-021-22584-4 

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Shallow marine ecosystem collapse and recovery during the Paleocene-Eocene Thermal Maximum

Abstract.

"The Paleocene-Eocene Thermal Maximum (PETM), the most well-studied transient hyperthermal event in Earth history, is characterized by prominent and dynamic changes in global marine ecosystems. Understanding such biotic responses provides valuable insights into future scenarios in the face of anthropogenic warming. However, evidence of the PETM biotic responses is largely biased towards deep-sea records, whereas shallow-marine evidence remains scarce and elusive. Here we investigate a shallow-marine microfaunal record from Maryland, eastern United States, to comprehensively document the shallow-marine biotic response to the PETM. We applied birth-death modeling to estimate the local diversity dynamics[...]"

 

Source: Elsevier
Authors: Skye Yunshu Tian  et al.
DOI: https://doi.org/10.1016/j.gloplacha.2021.103649

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Fifty Year Trends in Global Ocean Heat Content Traced to Surface Heat Fluxes in the Sub-Polar Ocean

Abstract.

"The ocean has absorbed approximately 90% of the accumulated heat in the climate system since 1970. As global warming accelerates, understanding ocean heat content changes and tracing these to surface heat input is increasingly important. We introduce a novel framework by organizing the ocean into temperature-percentiles from warmest to coldest, allowing us to trace ocean temperature changes to changes[...]"

 

Source: AGU- Advancing Earth And Space Science
Authors: Taimoor Sohail et al.
DOI: https://doi.org/10.1029/2020GL091439

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Effect of environmental history on the habitat-forming kelp Macrocystis pyrifera responses to ocean acidification and warming: a physiological and mol

Abstract.

"The capacity of marine organisms to adapt and/or acclimate to climate change might differ among distinct populations, depending on their local environmental history and phenotypic plasticity. Kelp forests create some of the most productive habitats in the world, but globally, many populations have been negatively impacted by multiple anthropogenic stressors. Here, we compare the physiological and molecular responses to ocean acidification (OA) and warming (OW) of two populations of the giant kelp[...]"

 

Source: Nature Scientific Reports
Authors: Pamela A. Fernández et al.
DOI: https://doi.org/10.1038/s41598-021-82094-7

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Low oxygen levels can help to prevent the detrimental effect of acute warming on mitochondrial efficiency in fish

Abstract.

"Aerobic metabolism of aquatic ectotherms is highly sensitive to fluctuating climates. Many mitochondrial traits exhibit phenotypic plasticity in response to acute variations in temperature and oxygen availability. These responses are critical for understanding the effects of environmental variations on aquatic ectotherms' performance. Using the European seabass, Dicentrarchus labrax, we determined the effects of acute warming and deoxygenation in vitro on mitochondrial respiratory capacities and mitochondrial[...]"

 

Source: The Royal Society Publishing 
Authors: Elisa Thoral et al.
DOI: https://doi.org/10.1098/rsbl.2020.0759

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Ocean acidification may slow the pace of tropicalization of temperate fish communities

Abstract.

"Poleward range extensions by warm-adapted sea urchins are switching temperate marine ecosystems from kelp-dominated to barren-dominated systems that favour the establishment of range-extending tropical fishes. Yet, such tropicalization may be buffered by ocean acidification, which reduces urchin grazing performance and the urchin barrens that tropical range-extending fishes prefer. Using ecosystems experiencing natural warming and acidification, we show that ocean acidification could buffer warming-facilitated[...]"

 

Source: Nature Climate Change
Authors: Ericka O. C. Coni et al.
DOI: https://doi.org/10.1038/s41558-020-00980-w

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Temperature and dissolved oxygen concentration in the Pacific Ocean at the northern region of the oxygen minimum zone off Mexico between the last two

Abstract.

"The changes in temperature and dissolved oxygen concentration in the Pacific Ocean in the northern region of the shallow oxygen minimum zone (OMZ) off Mexico were analyzed on the basis of the Word Ocean Database and a series of oceanographic cruises (LEGOZ-Mex). In order to test the changes in both parameters between two similar oceanographic scenarios according to the Pacific Decadal Oscillation (PDO), a comparison was made between the last two cool PDO phases of 1962–1974 and 2002–2012 when conditions[...]"

 

Source: Science Direct
Authors: E.D.Sánchez-Pérez et al.
DOI: https://doi.org/10.1016/j.jmarsys.2021.103607

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Antarctic icebergs reorganize ocean circulation during Pleistocene glacials

Abstract.

"The dominant feature of large-scale mass transfer in the modern ocean is the Atlantic meridional overturning circulation (AMOC). The geometry and vigour of this circulation influences global climate on various timescales. Palaeoceanographic evidence suggests that during glacial periods of the past 1.5 million years the AMOC had markedly different features from today1; in the Atlantic basin, deep waters of Southern Ocean origin[...]"

 

Source: Nature
Authors: Aidan Starr et al.
DOI: https://doi.org/10.1038/s41586-020-03094-7

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Zooplankton grazing of microplastic can accelerate global loss of ocean oxygen

Abstract.

"Global warming has driven a loss of dissolved oxygen in the ocean in recent decades. We demonstrate the potential for an additional anthropogenic driver of deoxygenation, in which zooplankton consumption of microplastic reduces the grazing on primary producers. In regions where primary production is not limited by macronutrient availability, the reduction of grazing pressure on primary producers causes export production to increase. Consequently, organic particle remineralisation in these regions[...]"

 

Source: Nature Communications
Authors: K. Kvale et al.
DOI: https://doi.org/10.1038/s41467-021-22554-w

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Antioxidant responses of the mussel Mytilus coruscus co-exposed to ocean acidification, hypoxia and warming

Abstract.

"In the present study, the combined effects of pH, dissolved oxygen (DO) and temperature levels on the antioxidant responses of the mussel Mytilus coruscus were evaluated. Mussels were exposed to two pH (8.1, 7.7-acidification), two DO (6 mg L−1, 2 mg L−1-hypoxia) and two temperature levels[...]"

 

Source: Science Direct
Authors: Fahim Ullah Khan et al
DOI: https://doi.org/10.1016/j.marpolbul.2020.111869

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Coastal eutrophication drives acidification, oxygen loss, and ecosystem change in a major oceanic upwelling system

Abstract.

"Global change is leading to warming, acidification, and oxygen loss in the ocean. In the Southern California Bight, an eastern boundary upwelling system, these stressors are exacerbated by the localized discharge of anthropogenically enhanced nutrients from a coastal population of 23 million people. Here, we use simulations with a high-resolution, physical–biogeochemical model to quantify the link between terrestrial [...]"

 

Source: PNAS- Proceedings of the National Academy of Sciences of the United States of America
Authors: Faycal Kessouri et al.
DOI: https://doi.org/10.1073/pnas.2018856118

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Global declines in coral reef calcium carbonate production under ocean acidification and warming

Abstract.

"Ocean warming and acidification threaten the future growth of coral reefs. This is because the calcifying coral reef taxa that construct the calcium carbonate frameworks and cement the reef together are highly sensitive to ocean warming and acidification. However, the global-scale effects of ocean warming and acidification on rates of coral reef net carbonate production remain poorly constrained despite a wealth of studies assessing their effects on the calcification of individual organisms[...]"

 

Source: PNAS- Proceedings of the National Academy of Sciences of the United States of America
Authors: Christopher E. Cornwall et al.
DOI: https://doi.org/10.1073/pnas.2015265118

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The poleward enhanced Arctic Ocean cooling machine in a warming climate

Abstract.

"As a cooling machine of the Arctic Ocean, the Barents Sea releases most of the incoming ocean heat originating from the North Atlantic. The related air-sea heat exchange plays a crucial role in both regulating the climate and determining the deep circulation in the Arctic Ocean and beyond. It was reported that the cooling efficiency of this cooling machine has decreased significantly. In this study, we find that the overall cooling efficiency did not really drop: When the cooling efficiency decreased in the southern Barents Sea[...]"

 

Source: Nature Communications
Authors: Qi Shu et al.
DOI: https://doi.org/10.1038/s41467-021-23321-7

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Zooplankton grazing of microplastic can accelerate global loss of ocean oxygen

Abstract.

"Global warming has driven a loss of dissolved oxygen in the ocean in recent decades. We demonstrate the potential for an additional anthropogenic driver of deoxygenation, in which zooplankton consumption of microplastic reduces the grazing on primary producers. In regions where primary production is not limited by macronutrient availability, the reduction of grazing pressure on primary producers causes export production to increase. Consequently, organic particle remineralisation in[...]"

 

Source: Nature Communications 
Authors: K. Kvale et al.
DOI: https://doi.org/10.1038/s41467-021-22554-w

Read the full article here.


Opposite response of strong and moderate positive Indian Ocean Dipole to global warming

Abstract.

"A strong positive Indian Ocean Dipole (pIOD) induces weather extremes such as the 2019 Australian bushfires and African floods. The impact is influenced by sea surface temperature (SST), yet models disagree on how pIOD SST may respond to greenhouse warming. Here we find increased SST variability of strong pIOD events, with strong equatorial eastern Indian Ocean cool anomalies, but decreased variability of moderate pIOD events, dominated by western warm anomalies[...]"

 

Source: Nature Climate Change
Authors: Wenju Cai et al.
DOI: https://doi.org/10.1038/s41558-020-00943-1

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Regional patterns and temporal evolution of ocean iron fertilization and CO2 drawdown during the last glacial termination

Abstract.

"The last time Earth's climate experienced geologically rapid global warming was associated with the last glacial termination, when atmospheric CO2 concentrations rose from 180 ppmv during the Last Glacial Maximum (LGM, 26-19 kaBP) to ∼260 ppmv by the early Holocene (12-8 kaBP). About one quarter of that difference is thought to be due to a stronger biological pump during glacial times, driven by increased aeolian dust deposition and hence greater iron availability in[...]"

 

Source: Science Direct
Authors: Fabrice Lambert et al.
DOI: https://doi.org/10.1016/j.epsl.2020.116675

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Impacts of hypoxic events surpass those of future ocean warming and acidification

Abstract.

"Over the past decades, three major challenges to marine life have emerged as a consequence of anthropogenic emissions: ocean warming, acidification and oxygen loss. While most experimental research has targeted the first two stressors, the last remains comparatively neglected. Here, we implemented sequential hierarchical mixed-model meta-analyses (721 control–treatment comparisons) to compare the impacts of oxygen conditions associated with the current and continuously intensifying hypoxic[...]"

 

Source: Nature Ecology and Evolution
Authors: Eduardo Sampaio et al.
DOI: https://doi.org/10.1038/s41559-020-01370-3

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Increased carbon capture by a silicate-treated forested watershed affected by acid deposition

Abstract.

"Meeting internationally agreed-upon climate targets requires carbon dioxide removal (CDR) strategies coupled with an urgent phase-down of fossil fuel emissions. However, the efficacy and wider impacts of CDR are poorly understood. Enhanced rock weathering (ERW) is a land-based CDR strategy requiring large-scale field trials. Here we show that a low 3.44 t ha−1 wollastonite treatment in an 11.8 ha acid-rain-impacted forested watershed in New Hampshire, USA, led to cumulative carbon capture by carbonic acid weathering of 0.025–0.13 t CO2 ha−1 over 15 years. Despite a 0.8–2.4 t CO2 ha−1 logistical carbon penalty from mining, grinding, transportation[...]"

 

Source: Biogeosciences
Authors: Lyla L. Taylor et al.
DOI: https://doi.org/10.5194/bg-18-169-2021

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Sensitivity of 21st-century projected ocean new production changes to idealized biogeochemical model structure

Abstract.

"While there is agreement that global warming over the 21st century is likely to influence the biological pump, Earth system models (ESM) display significant divergence in their projections of future new production. This paper quantifies and interprets the sensitivity of projected changes in new production in an idealized global ocean-biogeochemistry model. The model includes two tracers that explicitly represent nutrient transport, light- and nutrient-limited nutrient uptake by the ecosystem (new production), and export via sinking organic particles. Globally, new production declines with warming due to reduced surface nutrient availability, as expected. However, the magnitude[...]"

 

Source: Biogeosciences
Authors: Genevieve Jay Brett et al.
DOI: https://doi.org/10.5194/bg-2020-479

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Enhanced Organic Carbon Burial in Sediments of Oxygen Minimum Zones Upon Ocean Deoxygenation

Abstract.

"Oxygen minimum zones (OMZs) in the ocean are expanding. This expansion is attributed to global warming and may continue over the next 10 to 100 kyrs due to multiple climate CO2-driven factors. The expansion of oxygen-deficient waters has the potential to enhance organic carbon burial in marine sediments, thereby providing a negative feedback on global warming. Here, we study the response of dissolved oxygen in the ocean to increased phosphorus and iron inputs due to CO2-driven enhanced weathering and increased dust emissions, respectively. We use an ocean biogeochemical model[...]"

Source: frontiers in the Marine Science
Authors: Itzel Ruvalcaba Baroni et al.
DOI: https://doi.org/10.3389/fmars.2019.00839

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Latitudinal gradient in the respiration quotient and the implications for ocean oxygen availability

Abstract.

"Climate-driven depletion of ocean oxygen strongly impacts the global cycles of carbon and nutrients as well as the survival of many animal species. One of the main uncertainties in predicting changes to marine oxygen levels is the regulation of the biological respiration demand associated with the biological pump. Derived from the Redfield ratio, the molar ratio of oxygen to organic carbon consumed during respiration (i.e., the respiration quotient, r −O2:C  r−O2:C ) is consistently assumed constant but rarely, if ever, measured. Using a prognostic[...]"

 

Source: Proceedings of the National Academy of Sciences of the United States of America
Authors: Allison R. Moreno et al.
DOI:  https://doi.org/10.1073/pnas.2004986117

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The Northeast Atlantic is running out of excess carbonate in the horizon of cold-water corals communities

Abstract.

"The oceanic uptake of atmospheric carbon dioxide (CO2) emitted by human activities alters the seawater carbonate system. Here, the chemical status of the Northeast Atlantic is examined by means of a high-quality database of carbon variables based on the GO-SHIP A25 section (1997–2018). The increase of atmospheric CO2 leads to an increase in ocean anthropogenic carbon (Cant) and a decrease in carbonate that is unequivocal in the upper and mid-layers (0–2,500 m depth). In the mid-layer, the carbonate content in the Northeast Atlantic is maintained by the interplay between the northward spreading of recently conveyed Mediterranean Water with excess of carbonate and the arrival of subpolar-origin waters close to carbonate[...]".

Source: Nature Reviews Earth & Environment
Authors: Marcos Fontela et al.
DOI: https://doi.org/10.1038/s41598-020-71793-2

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Contrasting Upper and Deep Ocean Oxygen Response to Protracted Global Warming

Abstract.

"It is well established that the ocean is currently losing dissolved oxygen (O2) in response to ocean warming, but the long‐term, equilibrium response of O2 to a warmer climate is neither well quantified nor understood. Here we use idealized multimillennial global warming simulations with a comprehensive Earth system model to show that the equilibrium response in ocean O2 differs fundamentally from the ongoing transient response. After physical equilibration of the model (>4,000 years) under a two times preindustrial CO2 scenario, the deep ocean[...]"

Source: Advancing Earth and Space Science
Authors: T. L. Frölicher et al.
DOI: https://doi.org/10.1029/2020GB006601

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Substrate regulation leads to differential responses of microbial ammonia-oxidizing communities to ocean warming

Abstract.

"In the context of continuously increasing anthropogenic nitrogen inputs, knowledge of how ammonia oxidation (AO) in the ocean responds to warming is crucial to predicting future changes in marine nitrogen biogeochemistry. Here, we show divergent thermal response patterns for marine AO across a wide onshore/offshore trophic gradient. [...]"

Source: Nature Communications
Authors: Zhen-Zhen Zheng et al.
DOI: 10.1038/s41467-020-17366-3

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Twenty-first century ocean warming, acidification, deoxygenation, and upper-ocean nutrient and primary production decline from CMIP6 model projections

Abstract.

"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). [...]"

Source: Biogeosciences
Authors: Lester Kwiatkowski et al.
DOI: 10.5194/bg-17-3439-2020

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Is deoxygenation detectable before warming in the thermocline?

Abstract.

"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. [...]"

Source: Biogeosciences
Authors: Angélique Hameau et al.
DOI: 10.5194/bg-17-1877-2020

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Warming stimulates sediment denitrification at the expense of anaerobic ammonium oxidation

Abstract.

"Temperature is one of the fundamental environmental variables governing microbially mediated denitrification and anaerobic ammonium oxidation (anammox) in sediments. The GHG nitrous oxide (N2O) is produced during denitrification, but not by anammox, and knowledge of how these pathways respond to global warming remains limited. [...]"

Source: Nature Climate Change
Authors: Ehui Tan et al.
DOI: 10.1038/s41558-020-0723-2

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HKU study shows that control of anthropogenic atmospheric emissions can improve water quality in China’s coastal Seas

"A new research led by MPhil student Miss Yu Yan Yau and supervised by Dr Benoit Thibodeau from the Department of Earth Sciences and the Swire Institute of Marine Science, the University of Hong Kong (HKU), highlighted the importance of reducing fossil fuel combustion not only to curb the trend of global warming, but also to improve the quality of China’s coastal waters. The findings were recently published in the prestigious journal Environmental Science & Technology. [...]"

Source: The University of Hong Kong

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Our Vanishing World: Oceans

"As the human onslaught against life on Earth accelerates, no part of the biosphere is left pristine. The simple act of consuming more than we actually need drives the world’s governments and corporations to endlessly destroy more and more of the Earth to extract the resources necessary to satisfy our insatiable desires. In fact, an initiative of the World Economic Forum has just reported that ‘For the first time in history, more than 100 billion tonnes of materials are entering the global economy every year’ – see ‘The Circularity Gap Report 2020’– which means that, on average, every person on Earth uses more than 13 tonnes of materials each year extracted from the Earth. [...]"

Source: GlobalReasearch

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Multi-agency report highlights increasing signs and impacts of climate change in atmosphere, land and oceans

"New York / Geneva, 10 March 2020 - The tell-tale physical signs of climate change such as increasing land and ocean heat, accelerating sea level rise and melting ice are highlighted in a new report compiled by the World Meteorological Organization and an extensive network of partners. It documents impacts of weather and climate events on socio-economic development, human health, migration and displacement, food security and land and marine ecosystems. [...]"

Source: World Meteorological Organization (WMO)

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Uncovering diversity and metabolic spectrum of animals in dead zone sediments

Abstract.

"Ocean deoxygenation driven by global warming and eutrophication is a primary concern for marine life. Resistant animals may be present in dead zone sediments, however there is lack of information on their diversity and metabolism. Here we combined geochemistry, microscopy, and RNA-seq for estimating taxonomy and functionality of micrometazoans along an oxygen gradient in the largest dead zone in the world.  [...]"

Source: Communications Biology
Authors: Elias Broman et al.
DOI: 10.1038/s42003-020-0822-7

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Ocean Conference has potential to be a ‘global game-changer’

"“Life under water is essential to life on land”, said Tijjani Muhammad-Bande. The ocean produces “half of the oxygen we breathe” and provides food for millions of around the world, playing a “fundamental role in mitigating climate change as a major heat and carbon sink”. The Ocean Conference, which will run in Lisbon from 2 to 6 June, aims to propel science-based innovative solutions in the form of global ocean action. The worldwide ocean economy is valued at around $1.5 trillion dollars annually, as aquaculture is the fastest growing food sector and 350 million jobs world-wide are linked to fisheries. [...]"

Source: UN News

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Anaerobic Activity Is a Big Contributor in Marine “Dead Zones”

Climate models that do not account for anaerobic microbial activity may underestimate future expansion of oxygen-depleted waters.

"Certain parts of Earth’s oceans are so oxygen depleted that they can hardly sustain life. Climate models predict that these “dead zones” will expand as global warming progresses, affecting ecosystems, fisheries, and the climate itself. Now Lengger et al. provide new evidence that such predictions do not adequately account for the activity of anaerobic microbes that consume inorganic carbon within dead zones. [...]"

Source: EOS.org

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Record-Setting Ocean Warmth Continued in 2019

"Human-emitted greenhouse gases (GHGs) have resulted in a long-term and unequivocal warming of the planet (IPCC, 2019). More than 90% of the excess heat is stored within the world’s oceans, where it accumulates and causes increases in ocean temperature (Rhein et al., 2013; Abram et al., 2019). Because the oceans are the main repository of the Earth’s energy imbalance, measuring ocean heat content (OHC) is one of the best way to quantify the rate of global warming (Trenberth et al., 2016; Von Schuckmann et al., 2016; Cheng et al., 2018). [...]"

Source: Advances in Atmospheric Sciences
Authors: Lijing Cheng et al.
DOI: 10.1007/s00376-020-9283-7

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Record-setting ocean warmth continued in 2019

"A new analysis shows the world's oceans were the warmest in 2019 than any other time in recorded human history, especially between the surface and a depth of 2,000 meters. The study, conducted by an international team of 14 scientists from 11 institutes across the world, also concludes that the past ten years have been the warmest on record for global ocean temperatures, with the past five years holding the highest record. [...]"

Source: EurekAlert!

Read the full article here.


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. Ocean heat uptake during recent decades has been quantified using ocean temperature measurements. However, these estimates all use the same imperfect ocean dataset and share additional uncertainty due to sparse coverage, especially before 2007. Here, we provide an independent estimate by using measurements of atmospheric oxygen (O2) and carbon dioxide (CO2) – levels of which increase as the ocean warms and releases gases – as a whole ocean thermometer. [...]"

Source: Scientific Reports
Authors: L. Resplandy et al.
DOI: 10.1038/s41598-019-56490-z

Read the full article here.


Warming climate will impact dead zones in Chesapeake Bay

"In recent years, scientists have projected increasingly large summer dead zones in the Chesapeake Bay, areas where there is little or no oxygen for living things like crabs and fish to thrive, even as long-term efforts to reduce nutrient pollution continue. Researchers factored in local impacts of climate change to make projections of what the oxygen content of the Chesapeake Bay will look like in the future. [...]"

Source: Science Daily

Read the full article here.


Ocean acidification – a silently progressing crisis

"Ocean warming, acidification, deoxygenation, and marine heatwaves are all pressing marine issues that are quietly intensifying around the world. These challenges are diverse and occur on a massive scale, making it difficult for people to understand the full extent of the problem. To shed some light on this topic, the Sasakawa Peace Foundation (SPF) spoke with Mr. Tsunoda, Senior Research Fellow at the Ocean Policy Research Institute (OPRI). [...]"

Source: Sasakawa Peace Foundation

Read the full article here.


A crisis in the water is decimating this once-booming fishing town

"TOMBWA, Angola — His ancestors were Portuguese colonialists who settled on this otherworldly stretch of coast, wedged between a vast desert and the southern Atlantic. They came looking for the one thing this barren region had in abundance: fish.

By the time Mario Carceija Santos was getting into the fishing business half a century later, in the 1990s, Angola had won independence and the town of Tombwa was thriving. There were 20 fish factories strung along the bay, a constellation of churches and schools, a cinema hall built in art deco, and, in the central plaza, massive drying racks for the tons upon tons of fish hauled out of the sea. [...]"

Source: The Washington Post

Read the full article here.


Sensitivities to global change drivers may correlate positively or negatively in a foundational marine macroalga

Abstract.

"Ecological impact of global change is generated by multiple synchronous or asynchronous drivers which interact with each other and with intraspecific variability of sensitivities. In three near-natural experiments, we explored response correlations of full-sibling germling families of the seaweed Fucus vesiculosus towards four global change drivers: elevated CO2 (ocean acidification, OA), ocean warming (OW), combined OA and warming (OAW), nutrient enrichment and hypoxic upwelling. [...]"

Source: Scientific Reports
Authors: Balsam Al-Janabi et al.
DOI: 10.1038/s41598-019-51099-8

Read the full article here.


Combined effects of ocean acidification and temperature on larval and juvenile growth, development and swimming performance of European sea bass

Abstract.

"Ocean acidification and ocean warming (OAW) are simultaneously occurring and could pose ecological challenges to marine life, particularly early life stages of fish that, although they are internal calcifiers, may have poorly developed acid-base regulation. This study assessed the effect of projected OAW on key fitness traits (growth, development and swimming ability) in European sea bass (Dicentrarchus labrax) larvae and juveniles. [...]"

Source: PLoS One
Authors: Louise Cominassi etal.
DOI: 10.1371/journal.pone.0221283

Read the full article here.


Oxygen supersaturation protects coastal marine fauna from ocean warming

Abstract.

"Ocean warming affects the life history and fitness of marine organisms by, among others, increasing animal metabolism and reducing oxygen availability. In coastal habitats, animals live in close association with photosynthetic organisms whose oxygen supply supports metabolic demands and may compensate for acute warming. [...]"

Source: Science Advances 
Authors: Folco Giomi et al.
DOI:  10.1126/sciadv.aax1814

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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!

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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

Read the full article here.


Deglacial to Holocene Ocean Temperatures in the Humboldt Current System as Indicated by Alkenone Paleothermometry

Abstract.

"The response of the Humboldt Current System to future global warming is uncertain. Here we reconstruct alkenone‐derived near‐surface temperatures from multiple cores along the Peruvian coast to infer the driving mechanisms of upwelling changes for the last 20 kyr. Our records show a deglacial warming consistent with Antarctic ice‐core temperatures and a Mid‐Holocene cooling, which, in combination with other paleoceanographic records, suggest a strengthening of upwelling conditions. [...]"

Source: Geophysical Research Letters
Authors: Renato Salvatteci et al.
DOI: 10.1029/2018GL080634

Read the full article here.


Global warming today mirrors conditions leading to Earth's largest extinction event, study says

"More than two-thirds of life on Earth died off some 252 million years ago, in the largest mass extinction event in Earth's history.

Researchers have long suspected that volcanic eruptions triggered "the Great Dying," as the end of the Permian geologic period is sometimes called, but exactly how so many creatures died has been something of a mystery.

Now scientists at the University of Washington and Stanford believe their models reveal how so many animals were killed, and they see frightening parallels in the path our planet is on today.

Models of the effects of volcanic greenhouse gas releases showed the Earth warming dramatically and oxygen disappearing from its oceans, leaving many marine animals unable to breathe, according to a study published Thursday in the peer-reviewed journal Science. By the time temperatures peaked, about 80 percent of the oceans' oxygen, on average, had been depleted. Most marine animals went extinct. [...]"

Source: Phys.org

Read the full article here.

 


Temperature-dependent hypoxia explains biogeography and severity of end-Permian marine mass extinction

Abstract.

"Climate change triggered by volcanic greenhouse gases is hypothesized to have caused the largest mass extinction in Earth’s history at the end of the Permian Period (~252 million years ago). Geochemical evidence provides strong support for rapid global warming and accompanying ocean oxygen (O2) loss, but a quantitative link among climate, species’ traits, and extinction is lacking. To test whether warming and O2 loss can mechanistically account for the marine mass extinction, we combined climate model simulations with an established ecophysiological framework to predict the biogeographic patterns and severity of extinction. Those predictions were confirmed by a spatially explicit analysis of the marine fossil record. [...]"

Source: Science
Authors: Justin L. Penn et al.
DOI: 10.1126/science.aat1327

Read the full article here.


Major intensification of Atlantic overturning circulation at the onset of Paleogene greenhouse warmth

Abstract.

"During the Late Cretaceous and early Cenozoic the Earth experienced prolonged climatic cooling most likely caused by decreasing volcanic activity and atmospheric CO2 levels. However, the causes and mechanisms of subsequent major global warming culminating in the late Paleocene to Eocene greenhouse climate remain enigmatic. We present deep and intermediate water Nd-isotope records from the North and South Atlantic to decipher the control of the opening Atlantic Ocean on ocean circulation and its linkages to the evolution of global climate. [...]"

Source: Nature Communications
Authors: S. J. Batenburg et al.
DOI: 10.1038/s41467-018-07457-7

Read the full article here.


The evolving response of mesopelagic fishes to declining midwater oxygen concentrations in the southern and central California Current

Abstract.

"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.
DOI: 10.1093/icesjms/fsy154

Read the full article here.


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. [...]"

Source: eos.org

Read the full article here.


Volcanic eruptions once caused mass extinctions in the oceans – could climate change do the same?

"All animals, whether they live on land or in the water, require oxygen to breathe. But today the world’s oceans are losing oxygen, due to a combination of rising temperatures and changing ocean currents. Both factors are driven by human-induced climate change.

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. [...]"

Source: TheConversation

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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

Read the full article here.


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

Read the fulll article here.


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)

Read the full article here.


Middle Eocene greenhouse warming facilitated by diminished weathering feedback

Abstract.

"The Middle Eocene Climatic Optimum (MECO) represents a ~500-kyr period of global warming ~40 million years ago and is associated with a rise in atmospheric CO2 concentrations, but the cause of this CO2 rise remains enigmatic. Here we show, based on osmium isotope ratios (187Os/188Os) of marine sediments and published records of the carbonate compensation depth (CCD), that the continental silicate weathering response to the inferred CO2 rise and warming was strongly diminished during the MECO—in contrast to expectations from the silicate weathering thermostat hypothesis. [...]"

Source: Nature Communications
Authors: Robin van der Ploeg et al.
DOI: 10.1038/s41467-018-05104-9

Read the full article here.


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 CO2 input into the atmosphere was similar to the IPCC RCP8.5 emission scenario. Here we present sulfur-isotope data which record a positive 1 ‰ excursion during the PETM. Modeling suggests that significant parts of the ocean must have become sulfidic. The toxicity of hydrogen sulfide will render two of the largest and least explored ecosystems on Earth, the mesopelagic and bathypelagic zones, uninhabitable by multi-cellular organisms. This will affect many marine species whose eco-zones stretch into the deep ocean. [...]"

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

Read the full article here.


The Ocean is losing its breath: declining oxygen in the world's ocean and coastal waters; summary for policy makers

"Oxygen is critical to the health of the ocean. It structures aquatic ecosystems, impacts the biogeochemical cycling of carbon, nitrogen and other key elements, and is a fundamental requirement for marine life from the intertidal zone to the greatest depths of the ocean." [...]

Source: UNESCO (UNESDOC)
Authors: Denise Breitburg et al.

Get the full publication here.


How ocean warmth triggers glacial melting far away

"The melting of glaciers on one side of the globe can trigger disintegration of glaciers on the other side of the globe, as has been presented in a recent paper by a team of AWI scientists, who investigated marine microalgae preserved in glacial deposits and subsequently used their findings to perform climate simulations. The study highlights a process with alerting consequences for modern ice sheets: continuous warming of the ocean can result in a massive loss of polar ice mass, and consequently to rapid sea level rise."

Source: Science Daily

Read the full article here.


North Pacific freshwater events linked to changes in glacial ocean circulation

Abstract.

"There is compelling evidence that episodic deposition of large volumes of freshwater into the oceans strongly influenced global ocean circulation and climate variability during glacial periods. In the North Atlantic region, episodes of massive freshwater discharge to the North Atlantic Ocean were related to distinct cold periods known as Heinrich Stadials. [...]"

Source: Nature
Authors: E. Maier et al.
DOI: 10.1038/s41586-018-0276-y

Read the full article here.


Early Palaeozoic ocean anoxia and global warming driven by the evolution of shallow burrowing

Abstract.

"The evolution of burrowing animals forms a defining event in the history of the Earth. It has been hypothesised that the expansion of seafloor burrowing during the Palaeozoic altered the biogeochemistry of the oceans and atmosphere. However, whilst potential impacts of bioturbation on the individual phosphorus, oxygen and sulphur cycles have been considered, combined effects have not been investigated, leading to major uncertainty over the timing and magnitude of the Earth system response to the evolution of bioturbation. [...]"

Source: Nature Communications
Authors: Sebastiaan van de Velde et al.
DOI: 10.1038/s41467-018-04973-4

Read the full article here.


Will ocean zones with low oxygen levels expand or shrink?

"Computer simulations show that areas of the ocean that have low levels of dissolved oxygen will expand, but then shrink, in response to global warming — adding to an emerging picture of the finely balanced processes involved.

Global warming has reduced the amount of dissolved oxygen in the ocean by 2% since 1960. A major concern is that the rate of loss of dissolved oxygen has already increased by up to 20% in tropical waters, expanding the volume of regions called oxygen minimum zones (OMZs), where levels of dissolved oxygen are already very low."

Source: Nature
Authors: Laure Resplandy
DOI: 10.1038/d41586-018-05034-y

Read the full article here.


The possible roles of algae in restricting the increase in atmospheric CO2 and global temperature

Abstract.

"Anthropogenic inputs are increasing the CO2 content of the atmosphere, and the CO2 and total inorganic C in the surface ocean and, to a lesser degree, the deep ocean. The greenhouse effect of the increased CO2 (and, to a lesser extent, other greenhouse gases) is very probably the major cause of present global warming. The warming increases temperature of the atmosphere and the surface ocean to a greater extent than the deep ocean, with shoaling of the thermocline, decreasing nutrient flux to the surface ocean where there is greater mean photosynthetic photon flux density. [...]"

Source: European Journal of Phycology 
Author: John A. Raven
DOI: 10.1080/09670262.2017.1362593

Read the full article online.


Oxic-anoxic regime shifts mediated by feedbacks between biogeochemical processes and microbial community dynamics

Abstract.

"Although regime shifts are known from various ecosystems, the involvement of microbial communities is poorly understood. Here we show that gradual environmental changes induced by, for example, eutrophication or global warming can induce major oxic-anoxic regime shifts. We first investigate a mathematical model describing interactions between microbial communities and biogeochemical oxidation-reduction reactions. [...]"

Source: Nature Communications
Authors: Timothy Bush et al.
DOI: 10.1038/s41467-017-00912-x

Read the full article here.


Sound physiological knowledge and principles in modeling shrinking of fishes under climate change

Abstract.

"One of the main expected responses of marine fishes to ocean warming is decrease in body size, as supported by evidence from empirical data and theoretical modeling. The theoretical underpinning for fish shrinking is that the oxygen supply to large fish size cannot be met by their gills, whose surface area cannot keep up with the oxygen demand by their three-dimensional bodies. [...]"

Source: Global Change Biology
Authors: Daniel Pauly, William W. L. Cheung
DOI: 10.1111/gcb.13831

Read the full article here.


Ecological Energetic Perspectives on Responses of Nitrogen-Transforming Chemolithoautotrophic Microbiota to Changes in the Marine Environment

"Transformation and mobilization of bioessential elements in the biosphere, lithosphere, atmosphere and hydrosphere constitute the Earth's biogeochemical cycles, which are driven mainly by microorganisms through their energy and material metabolic processes. Without microbial energy harvesting from sources of light and inorganic chemical bonds for autotrophic fixation of inorganic carbon, there would not be sustainable ecosystems in the vast ocean. Although ecological energetics (eco-energetics) has been emphasized as a core aspect of ecosystem analyses and microorganisms largely control the flow of matter and energy in marine ecosystems, marine microbial communities are rarely studied from the eco-energetic perspective. [...]"

Source: Frontiers in Microbiology
Authors: Hongyue Dang and Chen-Tung A. Chen
DOI: 10.3389/fmicb.2017.01246

Full article


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