News

Effect of nutrient reductions on dissolved oxygen and pH: a case study of Narragansett bay

Abstract.

"To assess the consequences of nutrient reduction strategies on water quality under climate change, we investigated the long-term dynamics of dissolved oxygen (DO) and pH in Narragansett Bay (NB), a warming urbanized estuary in Rhode Island, where nitrogen loads have declined due to extensive wastewater treatment plant upgrades. We use 15 years (January 2005-December 2019) of measurements from the Narragansett Bay Fixed Site Monitoring network. Nutrient-enhanced phytoplankton growth can increase DO in the upper water column while subsequent respiration can reduce water column DO and enhance bottom water acidification, and vice-versa. [...]".

 

Source: Frontiers in Marine Science
Authors: Hongjie Wang et al.
DOI: https://doi.org/10.3389/fmars.2024.1374873

Read the full article here.


Oxygen declination in the coastal ocean over the twenty-first century: Driving forces, trends, and impacts

Abstract.

"Oxygen declination in coastal oceans has accelerated drastically in recent decades, both in terms of severity and spatial extent, and such disappearance of oxygen leads to dead zones where life can't survive. This phenomenon is mainly attributed to nutrient pollution and climate change due to intensified anthropogenic activities. The annual statistical oxygen mean concentrations showed the current deoxygenation trends based on (WOA_2001–2018) data comparison of 200 m below the surface water from the first two decades of the 21st century. [...]".

 

Source: Science Direct
Authors: Md Mesbah Uddin Bhuiyan et al.
DOI: https://doi.org/10.1016/j.cscee.2024.100621

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Climate, Oxygen, and the Future of Marine Biodiversity

Abstract.

"The ocean enabled the diversification of life on Earth by adding O2 to the atmosphere, yet marine species remain most subject to O2 limitation. Human industrialization is intensifying the aerobic challenges to marine ecosystems by depleting the ocean's O2 inventory through the global addition of heat and local addition of nutrients. Historical observations reveal an ∼2% decline in upper-ocean O2 and accelerating reports of coastal mass mortality events. The dynamic balance of O2 supply and demand provides a unifying framework for understanding these phenomena across scales from the global ocean to individual organisms. [...]".

 

Source: Annual Review of Marine Science
Authors: Curtis Deutsch et al.
DOI: https://doi.org/10.1146/annurev-marine-040323-095231

Read the full article here.


The past to unravel the future: Deoxygenation events in the geological archive and the anthropocene oxygen crisis

Abstract.

"Despite the observation that we are witnessing a true oxygen crisis, the ocean deoxygenation theme is getting less attention from the media and population compared to other environmental stressors concerning climate change. The current ocean oxygen crisis is characterized by a complex interplay of climatic, biological, and oceanographic processes acting at different time scales. Earth system models offer insights into future deoxygenation events and their potential extent [...]".

 

Source: Science Direct
Authors: Alan Maria Mancini et al.
DOI: https://doi.org/10.1016/j.earscirev.2023.104664

Read the full article here.


Can green hydrogen production be used to mitigate ocean deoxygenation? A scenario from the Gulf of St. Lawrence

Abstract.

"Ocean deoxygenation and expansion and intensification of hypoxia in the ocean are a major, growing threat to marine ecosystems. Measures currently used to protect marine biodiversity (e.g., marine protected areas) are ineffective in countering this threat. Here, we highlight the example of the Gulf of St. Lawrence in eastern Canada, where oxygen loss is not only due to eutrophication (which can be mitigated by nutrient controls) but also is a consequence of ocean circulation change and warming. Climate-related loss of oxygen will be an increasingly widespread source of risk to marine biodiversity over this century. [...]".

 

Source: Springer Nature
Authors: Douglas W. R. Wallace et al.
DOI: https://doi.org/10.1007/s11027-023-10094-1

Read the full article here.


Editorial: Constraining uncertainties in hindcasts and future projections of marine deoxygenation

Abstract.

"Ocean deoxygenation is a key stressor for marine ecosystems and biogeochemical cycles (Gruber, 2011; Breitburg et al., 2018). Climate projections based on Earth system models (ESMs) suggest that the global oxygen inventory will undergo a significant decline over the next century under persistent greenhouse gas emissions (Bopp et al., 2013; Kwiatkowski et al., 2020). Oxygen minimum zones (OMZs) located close to productive eastern boundary upwelling systems (EBUSs) and the Arabian Sea may expand or shift in spatial extent dramatically, thereby impacting regional marine habitats (Stramma et al., 2012) and ecosystem services (Lachkar et al., 2023). [...]".

 

Source: Frontiers in Marine Science
Authors: Masahito Shigemitsu et al.
DOI: https://doi.org/10.3389/fmars.2023.1355015

Read the full article here.


Sensitivity of the thermohaline circulation during the Messinian: Toward constraining the dynamics of Mediterranean deoxygenation

Abstract.

"During the Messinian, the sensitivity of the Mediterranean Basin to ecosystem perturbation was enhanced in response to the progressive restriction of water exchange with the Atlantic Ocean. The widespread deposition of organic-rich layers (i.e. sapropel) during the Messinian testifies the perturbation of the carbon and oxygen cycles; indeed, these sediments were deposited under conditions of oxygen starvation, presumably in response to a periodic deterioration of the thermohaline circulation strength. [...]".

 

Source: Science Direct 
Authors: Alan Maria Mancini et al.
DOI: https://doi.org/10.1016/j.dsr.2023.104217

Read the full article here.


Climatic Changes in North Atlantic O2 Amplified by Temperature Sensitivity of Phytoplankton Growth

Abstract.

"Ocean warming is associated with a decline in the global oxygen (O2) inventory, but the ratio of O2 loss to heat gain is poorly understood. We analyzed historical variability in temperature (T), O2, and nitrate (N⁢O3−) in hydrographic observations and model simulations of the North Atlantic, a relatively well-sampled region that is important for deep ocean ventilation. Multidecadal fluctuations of O2 concentrations in subpolar thermocline waters (100–700 m) are correlated with changes in their heat content, with a slope 35% steeper than that expected from thermal solubility. [...]".

 

Source: Wiley Online Library
Authors: Andrew J. Margolskee et al.
DOI: https://doi.org/10.1029/2023GB007930

Read the full article here.


Mentoring the next generation of ocean deoxygenation and acidification scientists

Intro.

"UNESCO’s Intergovernmental Oceanographic Commission (IOC/UNESCO), El Centro de Estudios Avanzados en Zonas Áridas (CEAZA) and the Universidad Catolica del Norte, as well as many other partners and sponsors organized the GOOD-OARS-CLAP-COPAS Summer School from 6-12 November 2023 in La Serena, Chile, to teach the latest science of ocean acidification and deoxygenation."

Source: IOC-UNESCO

For further information, please read here


Combined effects of ocean deoxygenation, acidification, and phosphorus limitation on green tide macroalga, Ulva prolifera

Abstract.

"Ocean deoxygenation, acidification, and decreased phosphorus availability are predicted to increase in coastal ecosystems under future climate change. However, little is known regarding the combined effects of such environmental variables on the green tide macroalga Ulva prolifera. Here, we provide quantitative and mechanistic understanding of the acclimation mechanisms of U. prolifera to ocean deoxygenation, acidification, and phosphorus limitation under both laboratory and semi-natural (mesocosms) conditions. [...]".

 

Source: Science Direct
Authors: Xintong Huang et al.
DOI: https://doi.org/10.1016/j.scitotenv.2023.164982

Read the full article here.


Impacts and uncertainties of climate-induced changes in watershed inputs on estuarine hypoxia

Abstract.

"Multiple climate-driven stressors, including warming and increased nutrient delivery, are exacerbating hypoxia in coastal marine environments. Within coastal watersheds, environmental managers are particularly interested in climate impacts on terrestrial processes, which may undermine the efficacy of management actions designed to reduce eutrophication and consequent low-oxygen conditions in receiving coastal waters. However, substantial uncertainty accompanies the application of Earth system model (ESM) projections to a regional modeling framework when quantifying future changes to estuarine hypoxia due to climate change. [...]".

 

Source: Biogeosciences
Authors: Kyle E. Hinson et al.
DOI: https://doi.org/10.5194/bg-20-1937-2023

Read the full article here.


Role of climate variability on deep-water dynamics and deoxygenation during sapropel deposition ...

Full title: "Role of climate variability on deep-water dynamics and deoxygenation during sapropel deposition: New insights from a palaeoceanographic empirical approach"

Abstract.

"Modern marine settings are experiencing rapid deoxygenation mainly forced by global warming and anthropogenic eutrophication. Therefore, studies that assess the role of climate variability in large spatiotemporal deoxygenations during past climate changes are needed to better comprehend the consequences of the current global warming and ocean deoxygenation. [...]".

 

Source: Science Direct
Authors: Ricardo D. Monedero-Contreras et al.
DOI: https://doi.org/10.1016/j.palaeo.2023.111601

Read the full article here.


A well-oxygenated eastern tropical Pacific during the warm Miocene

Abstract.

"The oxygen content of the oceans is susceptible to climate change and has declined in recent decades, with the largest effect in oxygen-deficient zones (ODZs), that is, mid-depth ocean regions with oxygen concentrations <5 μmol kg−1 (ref.). Earth-system-model simulations of climate warming predict that ODZs will expand until at least 2100. The response on timescales of hundreds to thousands of years, however, remains uncertain. Here we investigate changes in the response of ocean oxygenation during the warmer-than-present Miocene Climatic Optimum (MCO; 17.0–14.8 million years ago (Ma)). [...]".

 

Source: Nature
Authors: Anya V. Hess et al.
DOI: https://doi.org/10.1038/s41586-023-06104-6

Read the full article here.


Impacts of Deoxygenation and Hypoxia on Shark Embryos Anti-Predator Behavior and Oxidative Stress

Abstract. 

"Climate change is leading to the loss of oxygen content in the oceans and endangering the survival of many marine species. Due to sea surface temperature warming and changing circulation, the ocean has become more stratified and is consequently losing its oxygen content. Oviparous elasmobranchs are particularly vulnerable as they lay their eggs in coastal and shallow areas, where they experience significant oscillations in oxygen levels. Here, we investigated the effects of deoxygenation (93% air saturation) and hypoxia (26% air saturation) during a short-term period (six days) on the anti-predator avoidance behavior and physiology [...]".

 

Source: MDPI
Authors: Jaquelino Varela et al.
DOI: https://doi.org/10.3390/biology12040577

Read the full article here.


Early detection of anthropogenic climate change signals in the ocean interior

Abstract. 

"Robust detection of anthropogenic climate change is crucial to: (i) improve our understanding of Earth system responses to external forcing, (ii) reduce uncertainty in future climate projections, and (iii) develop efficient mitigation and adaptation plans. Here, we use Earth system model projections to establish the detection timescales of anthropogenic signals in the global ocean through analyzing temperature, salinity, oxygen, and pH evolution from surface to 2000 m depths. For most variables, anthropogenic changes emerge earlier in the interior ocean than at the surface, due to the lower background variability at depth. [...]".

 

Source: Nature 
Authors: Jerry F. Tjiputra et al.
DOI: https://doi.org/10.1038/s41598-023-30159-0

Read the full article here.


Aquatic Productivity under Multiple Stressors

Abstract. 

"Aquatic ecosystems are responsible for about 50% of global productivity. They mitigate climate change by taking up a substantial fraction of anthropogenically emitted CO2 and sink part of it into the deep ocean. Productivity is controlled by a number of environmental factors, such as water temperature, ocean acidification, nutrient availability, deoxygenation and exposure to solar UV radiation. Recent studies have revealed that these factors may interact to yield additive, synergistic or antagonistic effects. While ocean warming and deoxygenation are supposed to affect mitochondrial respiration oppositely [...]".

 

Source: MDPI
Authors: Donat-P. Häder & Kunshan Gao
DOI: https://doi.org/10.3390/w15040817

Read the full article here.


Climate Change Impacts on Dissolved Oxygen Concentration in Marine and Coastal Waters around the UK and Ireland

Abstract. 

"What is already happening

  • Since the 1960s, the global oceanic oxygen content has declined by more than 2%.
  • Sustained observations in the North Sea reveal the recent onset of oxygen deficiency in late summer, partly due to ocean warming. The intensity and extent of oxygen deficiency has also increased over time. [...]".

 

Source: Marine Climate Change Impacts Partnership  
Authors: Claire Mahaffey et al.
DOI: 10.14465/2023.reu07.oxy

Read the full article here.


Editorial: Regional coastal deoxygenation and related ecological and biogeochemical modifications in a warming climate

Abstract. 

"Coastal ecosystems play tremendous roles in socio-economic development, but their functions are degrading due to human activities. One of the most alarming degradations is coastal deoxygenation, driven primarily by the over-enrichment of anthropogenic nutrients and organic matter (eutrophication) in the coastal waters. The coastal deoxygenation has led to the worldwide spread of hypoxic zones (where dissolved oxygen concentration is less than 2 mg/L), with the number of reported hypoxic sites increasing from 45 in the 1960s to around 700 nowadays. Besides being perturbed by human activities locally, coastal waters respond more rapidly than [...]".

 

Source: Frontiers 
Authors: Wenxia Zhang et al.
DOI: https://doi.org/10.3389/fmars.2023.1146877

Read the full article here.


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

Read the full article here.


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

Read the full article here.


Oxygen and irradiance constraints on visual habitat in a changing ocean: The luminoxyscape

Abstract. 

"Changing oxygen conditions are altering the distribution of many marine animals. Zooplankton vertical distributions are primarily attributed to physiological tolerance and/or avoidance of visual predation. Recent findings reveal that visual function in marine larvae is highly sensitive to oxygen availability, but it is unknown how oxygen, which affects light sensitivity and generates limits for vision, may affect the distribution of animals that rely heavily on this sensory modality. This study introduces the concept of a “visual luminoxyscape” to demonstrate how combinations of limiting oxygen and light could constrain the habitat of marine larvae with oxygen-demanding vision. [...]".

 

Source: Wiley Online Library
Authors: Lillian R. McCormick et al.
DOI: https://doi.org/10.1002/lol2.10296

Read the full article here.


Mercury stable isotopes suggest reduced foraging depth in oxygen minimum zones for blue sharks

Abstract. 

"Oxygen minimum zones (OMZs) are currently expanding across the global ocean due to climate change, leading to a compression of usable habitat for several marine species. Mercury stable isotope compositions provide a spatially and temporally integrated view of marine predator foraging habitat and its variability with environmental conditions. Here, we analyzed mercury isotopes in blue sharks Prionace glauca from normoxic waters in the northeastern Atlantic and from the world's largest and shallowest OMZ, located in the northeastern Pacific (NEP). [...]".

 

Source: Science Direct 
Authors: Gaël Le Croizier et al.
DOI: https://doi.org/10.1016/j.marpolbul.2022.113892

Read the full article here.


Competing and accelerating effects of anthropogenic nutrient inputs on climate-driven changes in ocean carbon and oxygen cycles

Abstract. 

"Nutrient inputs from the atmosphere and rivers to the ocean are increased substantially by human activities. However, the effects of increased nutrient inputs are not included in the widely used CMIP5 Earth system models, which introduce bias into model simulations of ocean biogeochemistry. Here, using historical simulations by an Earth system model with perturbed atmospheric and riverine nutrient inputs, we show that the contribution of anthropogenic nutrient inputs to past global changes in ocean biogeochemistry is of similar magnitude to the effect of climate change. [...]". 

 

Source: Science Advances
Authors: Akitomo Yamamoto et al. 
DOI: 10.1126/sciadv.abl9207

Read the full article here.


Responses of Horizontally Expanding Oceanic Oxygen Minimum Zones to Climate Change Based on Observations

Abstract.

"Due to climate change, global oceanic dissolved oxygen (DO) has been decreasing, and oxygen minimum zones (OMZs) have been expanding. Here, we estimate the annual global and regional OMZ areas using geostatistical regression combined with Monte Carlo. From 1960 to 2019, annual global OMZ20 (DO < 20 μmol/kg) and OMZ60 (DO < 60 μmol/kg) areas cover 5%–14% and 15%–32% of the global ocean, respectively. The global and most regional OMZ areas after the late 2000s were all significantly larger than those in previous years. [...]".

 

Source: Wiley Online Library 

Authors: Yuntao Zhou et al.

DOI: https://doi.org/10.1029/2022GL097724

Read the full article here.


Ocean currents as a potential dispersal pathway for Antarctica’s most persistent non-native terrestrial insect

Abstract.

"The non-native midge Eretmoptera murphyi is Antarctica’s most persistent non-native insect and is known to impact the terrestrial ecosystems. It inhabits by considerably increasing litter turnover and availability of soil nutrients. The midge was introduced to Signy Island, South Orkney Islands, from its native South Georgia, and routes of dispersal to date have been aided by human activities, with little known about non-human-assisted methods of dispersal. This study is the first to determine the potential for dispersal of a terrestrial invertebrate species in Antarctica by combining physiological sea water tolerance data with quantitative assessments[...]"

 

Source: Polar Biology
Authors: Jesamine C. Bartlett  et al.
DOI: https://doi.org/10.1007/s00300-020-02792-2

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The soundscape of the Anthropocene ocean

Abstract.

"Oceans have become substantially noisier since the Industrial Revolution. Shipping, resource exploration, and infrastructure development have increased the anthrophony (sounds generated by human activities), whereas the biophony (sounds of biological origin) has been reduced by hunting, fishing, and habitat degradation. Climate change is affecting geophony (abiotic, natural sounds). Existing evidence shows that anthrophony affects marine animals[...]".

 

Source: Science
Authors: Carlos M. Duarte et al.
DOI: 10.1126/science.aba4658

Read the full article here.


Protecting the global ocean for biodiversity, food and climate

Abstract.

"The ocean contains unique biodiversity, provides valuable food resources and is a major sink for anthropogenic carbon. Marine protected areas (MPAs) are an effective tool for restoring ocean biodiversity and ecosystem services1,2, but at present only 2.7% of the ocean is highly protected3. This low level of ocean protection is due largely to conflicts with fisheries and other extractive uses. To address this issue[...]"

 

Source: Nature
Authors: Enric Sala et al.
DOI: https://doi.org/10.1038/s41586-021-03371-z

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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.[...]"

 

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

Read the full article here.


Investigating the Roles of External Forcing and Ocean Circulation on the Atlantic Multidecadal SST Variability in a Large Ensemble Climate Model Hiera

Abstract.

"This paper attempts to enhance our understanding of the causes of Atlantic Multidecadal Variability, the AMV. Following the literature, we define the AMV as the SST averaged over the North Atlantic basin, linearly detrended and low-pass filtered. There is an ongoing debate about the drivers of the AMV, which include internal variability generated from the ocean or atmosphere (or both), and external radiative forcing. We test the role of these factors in explaining the time history, variance, and spatial pattern of the AMV using[...]"

 

Source: American Meteorological Soceity 
Authors: Lisa N. Murphy et al.
DOI: https://doi.org/10.1175/JCLI-D-20-0167.1

Read the full article here.

 

 


Current Atlantic Meridional Overturning Circulation weakest in last millennium

Abstract.

"The Atlantic Meridional Overturning Circulation (AMOC)—one of Earth’s major ocean circulation systems—redistributes heat on our planet and has a major impact on climate. Here, we compare a variety of published proxy records to reconstruct the evolution of the AMOC since about AD 400. A fairly consistent picture of the AMOC emerges: after a long and relatively stable period, there was an initial weakening starting in the nineteenth century, followed by a second, more rapid, decline in the mid-twentieth[...]"

 

Source: Nature Geosciences
Authors: L. Caesar et al.
DOI: https://doi.org/10.1038/s41561-021-00699-z

Read the full article here.


Mixing by Oceanic Lee Waves

Abstract.

"Oceanic lee waves are generated in the deep stratified ocean by the flow of ocean currents over sea floor topography, and when they break, they can lead to mixing in the stably stratified ocean interior. While the theory of linear lee waves is well established, the nonlinear mechanisms leading to mixing are still under investigation. Tidally driven lee waves have long been observed in the ocean, along with associated mixing, but observations of lee waves forced by geostrophic eddies are relatively sparse and largely indirect[...]"

 

Source: Annual Reviews
Authors: Sonya Legg
DOI: https://doi.org/10.1146/annurev-fluid-051220-043904

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Multi‐Century Impacts of Ice Sheet Retreat on Sea Level and Ocean Tides in Hudson Bay

Abstract.

"Past and modern large‐scale ice sheet loss results in geographically variable sea level changes. At present, in Hudson Bay, Canada, sea level is decreasing due to glacial isostatic adjustment, which represents a departure from the globally averaged sea level rise. However, there are large uncertainties in future sea level trends with further polar ice sheet retreat in the coming centuries. Sea level changes affect ocean tides considerably because tides are highly sensitive to changes in bathymetry. Here, we present multi‐century sea level projections associated with a suite of past and future ice loss scenarios and consider the impact of these changes on ocean tides[...]"

Source: Advancing Earth and Space Science
Authors: A.‐M. Hayden et al.
DOI: https://doi.org/10.1029/2019JC015104

Read the full article here.


Ideas and perspectives: A strategic assessment of methane and nitrous oxide measurements in the marine environment

Abstract.

"In the current era of rapid climate change, accurate characterization of climate-relevant gas dynamics – namely production, consumption, and net emissions – is required for all biomes, especially those ecosystems most susceptible to the impact of change. Marine environments include regions that act as net sources or sinks for numerous climate-active trace gases including methane (CH4) and nitrous oxide (N2O). The temporal and spatial distributions of CH4 and N2O are controlled by the interaction of complex biogeochemical and physical processes. To evaluate and quantify how these mechanisms affect marine CH4 and N2O cycling requires a combination of traditional scientific disciplines including oceanography, microbiology, and numerical modeling[...]"

Source: Biogeosciences
Authors: Samuel T. Wilson et al.
DOI: https://doi.org/10.5194/bg-17-5809-2020

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Organic matter composition and heterotrophic bacterial activity at declining summer sea ice in the central Arctic Ocean

Abstract.

"The Arctic Ocean is highly susceptible to climate change as evidenced by rapid warming and the drastic loss of sea ice during summer. The consequences of these environmental changes for the microbial cycling of organic matter are largely unexplored. Here, we investigated the distribution and composition of dissolved organic matter (DOM) along with heterotrophic bacterial activity in seawater and sea ice of the Eurasian Basin at the time of the record ice minimum in 2012. Bacteria in seawater were highly responsive to fresh organic matter and remineralized on average 55% of primary production in the upper mixed layer. Correlation analysis showed that the accumulation of dissolved combined carbohydrates (DCCHO) and dissolved[...]"

 

Source: Association for the Sciences Limnology and Oceanography
Authors: Judith Piontek et al.
DOI: https://doi.org/10.1002/lno.11639

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Increasing ocean stratification over the past half-century

Abstract.

"Seawater generally forms stratified layers with lighter waters near the surface and denser waters at greater depth. This stable configuration acts as a barrier to water mixing that impacts the efficiency of vertical exchanges of heat, carbon, oxygen and other constituents. Previous quantification of stratification change has been limited to simple differencing of surface and 200-m depth changes and has neglected the spatial complexity of ocean density change. Here, we quantify changes in ocean stratification down[...]"

 

Source: Nature Climate Change
Authors: Guancheng Li  et al.
DOI: https://doi.org/10.1038/s41558-020-00918-2

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Observing the Global Ocean with Biogeochemical-Argo

Abstract.

"Biogeochemical-Argo (BGC-Argo) is a network of profiling floats carrying sensors that enable observation of as many as six essential biogeochemical and bio-optical variables: oxygen, nitrate, pH, chlorophyll a, suspended particles, and downwelling irradiance. This sensor network represents today's most promising strategy for collecting temporally and vertically resolved observations of biogeochemical properties throughout the ocean. All data are freely available within 24 hours of transmission. These data fill large gaps in ocean-observing systems and support three ambitions: gaining a better understanding of biogeochemical processes (e.g., the biological[...]"

 

Source: Annual Review of Marine Science
Authors: Hervé Claustre et al.
DOI: https://doi.org/10.1146/annurev-marine-010419-010956

Read the full article here.

 

 


Cretaceous oceanic anoxic events prolonged by phosphorus cycle feedbacks

Abstract.

"Oceanic anoxic events (OAEs) document major perturbations of the global carbon cycle with repercussions for the Earth's climate and ocean circulation that are relevant to understanding future climate trends. Here, we compare the onset and development of Cretaceous OAE1a and OAE2 in two drill cores with unusually high sedimentation rates from the Vocontian Basin (southern France) and Tarfaya Basin (southern Morocco). OAE1a and OAE2 exhibit remarkable similarities in the evolution of their carbon isotope (δ13C) records, with long-lasting negative excursions preceding the onset of the main positive excursions, supporting the view that both OAEs were triggered by massive emissions of volcanic CO2 into the atmosphere. However, there are substantial differences, notably in the durations of individual phases within the δ13C positive excursions of both OAEs. [...]"

Source: Climate of the Past
Authors: Sebastian Beil et al.
DOI: 10.5194/cp-16-757-2020

Read the full article here.


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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UK's lost sea meadows to be resurrected in climate fight

First seagrass restoration in Britain will capture carbon rapidly and offer habitat for lost marine life

 

“We think this whole bay was once carpeted with seagrass,” says Evie Furness, waving across the sparkling, sunlit waters of Dale Bay in Pembrokeshire, Wales. The underwater meadow is long gone though, a victim of past pollution and shipping. So from a boat half a mile from shore, Furness is feeding a long rope into the water, which carries a little hessian bag of seagrass seeds every metre. “We’ve passed the 800,000 seed mark now,” she says. [...]"

Source: The Guardian

Rad the full article here.


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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Even fish at the bottom of the ocean can’t escape climate change

"The fish that live at the bottom of the sea are a hardy bunch. They’re adapted to handle crushing pressure, little to no sunlight, and a meager supply of food. But these otherwise gritty fish are also very sensitive to changes in the climate of the water around them, a new study suggests.

Scientists surveyed different patches of seafloor in the Gulf of California and saw that variations in temperature and oxygen levels had a huge impact on whether the fish community was thriving or sparse. In particular, the researchers found that one specific combination—warmer waters mixed with low oxygen levels—didn’t bode well for deep sea fish. This means that these creatures are likely to be vulnerable to the impacts of climate change, the researchers reported March 5 in Marine Ecology Progress Series. [...]"

Source: Popular Science
 

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Defining Southern Ocean fronts and their influence on biological and physical processes in a changing climate

Abstract.

"The Southern Ocean is a critical component of the global climate system and an important ecoregion that contains a diverse range of interdependent flora and fauna. It also hosts numerous fronts: sharp boundaries between waters with different characteristics. As they strongly influence exchanges between the ocean, atmosphere and cryosphere, fronts are of fundamental importance to the climate system. However, rapid advances in physical oceanography over the past 20 years have challenged previous definitions of fronts and their response to anthropogenic climate change. [...]"

Source: Nature Climate Change
Authors: Christopher C. Chapman et al.
DOI: 10.1038/s41558-020-0705-4

Read the full article here.


Trends and decadal oscillations of oxygen and nutrients at 50 to 300 m depth in the equatorial and North Pacific

Abstract.

"A strong oxygen-deficient layer is located in the upper layers of the tropical Pacific Ocean and deeper in the North Pacific. Processes related to climate change (upper-ocean warming, reduced ventilation) are expected to change ocean oxygen and nutrient inventories. In most ocean basins, a decrease in oxygen (“deoxygenation”) and an increase in nutrients have been observed in subsurface layers. Deoxygenation trends are not linear and there could be multiple influences on oxygen and nutrient trends and variability. [...]"

Source: Biogeosciences
Authors: Lothar Stramma et al.
DOI: 10.5194/bg-17-813-2020

Read the full article here.


Preparatory Meeting Stresses 2020 as a New Chapter of Ocean Action

"Participants at the 2020 UN Ocean Conference Preparatory Meeting highlighted the importance of a healthy ocean in implementing and achieving the SDGs and stressed that 2020 must be a year of concrete action for the ocean. The 2020 Ocean Conference is one of the first milestones of the UN Secretary-General’s Decade of Action for the SDGs and is expected to provide inputs into the High-level Political Forum on Sustainable Development (HLPF) and the UN Decade of Ocean Science for Sustainable Development. [...]"

Read the full article here.


No “Ocean Super-Year” without Marine Regions

"This new decade starts at a critical moment for the future of the Ocean. There is strong agreement among experts that decisions taken in the next ten years will be critical for the future of the Ocean. The current ecological crisis demands a radical shift in the way we treat the marine environment, its precious wildlife, and its invaluable natural resources. We are witnessing continued loss of biodiversity, overfishing, habitat destruction, pollution, and many other serious impacts from human activities – all compounded by climate change, Ocean deoxygenation and acidification. [...]"

Source: International Institute for Sustainable Development

Read the full article here.


When microbiologists plunge into the ocean

Microbiologists stake their claim: assessing climate change involves new ways of studying the ocean’s microbes.

"Microbiology wants in. No longer should microbes and microbial processes be left out of climate change assessments, state 33 researchers from nine countries in their consensus statement1, “Scientists’ warning to humanity: microorganisms and climate change.” There’s a “need to act,” the authors write. By underappreciating the importance of microbial processes both on land and in the oceans, “we fundamentally limit our understanding of Earth’s biosphere and response to climate change and thus jeopardize efforts to create an environmentally sustainable future.” [...]"

Source: Nature Methods 
Authors: Vivien Marx
DOI: 10.1038/s41592-020-0736-9

Read the full article here.


Climate Change and Harmful Algal Blooms: Insights and perspective

Abstract.

"Climate change is transforming aquatic ecosystems. Coastal waters have experienced progressive warming, acidification, and deoxygenation that will intensify this century. At the same time, there is a scientific consensus that the public health, recreation, tourism, fishery, aquaculture, and ecosystem impacts from harmful algal blooms (HABs) have all increased over the past several decades. [...]"

Source: Harmful Algae
Author: Christopher J.Gobler
DOI: 10.1016/j.hal.2019.101731

Read the full article here.


Ocean deoxygenation : everyone’s problem

Abstract.

"The ocean represents 97% of the physical habitable space on the planet and is central to sustaining all life on Earth. Since 2000 significant and dedicated effort has been directed at raising awareness and understanding of the consequences of greenhouse gas emissions on the ocean. Carbon dioxide emitted by human activities is driving the ocean towards more acidic conditions. Only in the past decade has it started to become more widely recognized that the temperature of the global ocean is also being significantly affected as a result of the effect that the carbon dioxide and other potent greenhouse gases are having in the Earth’s atmosphere. [...]"

Source: IUCN
Authors: D. Laffoley and J. M. Baxter
DOI: 10.2305/IUCN.CH.2019.13.en

Read the full article here.


Article Open Access Published: 29 November 2019 Role of synoptic activity on projected changes in upwelling-favourable winds at the ocean’s eastern bo

Abstract.

"The climate of the ocean’s eastern boundaries is strongly influenced by subtropical anticyclones, which drive a surface wind stress that promotes coastal upwelling of nutrient-rich subsurface water that supports high primary productivity and an abundance of food resources. Understanding the projected response of upwelling-favourable winds to climate change has broad implications for coastal biogeochemistry, ecology, and fisheries. [...]"

Source: npj Climate and Atmospheric Science
Authors: Catalina Aguirre et al.
DOI: 10.1038/s41612-019-0101-9

Read the full article here.


Large projected decline in dissolved oxygen in a eutrophic estuary due to climate change

Abstract.

"Climate change is known to cause deoxygenation in the open ocean, but its effects on eutrophic and seasonally hypoxic estuaries and coastal oceans are less clear. Using Chesapeake Bay as a study site, we conducted climate downscaling projections for dissolved oxygen and found that the hypoxic and anoxic volumes would increase by 10‐30% between the late 20th and mid‐21st century. [...]"

Source: JGR Oceans
Authors: Wenfei Ni et al. 
DOI: 10.1029/2019JC015274

Read the full article here.


Meeting climate targets by direct CO2 injections: what price would the ocean have to pay?

Abstract.

"We investigate the climate mitigation potential and collateral effects of direct injections of captured CO2 into the deep ocean as a possible means to close the gap between an intermediate CO2 emissions scenario and a specific temperature target, such as the 1.5 C target aimed for by the Paris Agreement. For that purpose, a suite of approaches for controlling the amount of direct CO2 injections at 3000 m water depth are implemented in an Earth system model of intermediate complexity. [...]"

Source: Earth System Dynamics
Authors: Fabian Reith et al.
DOI: 10.5194/esd-10-711-2019

Read the full article here.


Oceanic organic carbon as a possible first-order control on the carbon cycle during the Bathonian–Callovian

Abstract.

"Oceans are the largest, readily exchangeable, superficial carbon reservoir; a current challenge in investigating past and present environments and predict future evolution relates to the role of oceanic carbon in regulating Earths' carbon cycle and climate. At least one paired δ13Ccarb-TOC decoupling event is noted in the Late Bathonian–Early Callovian. [...]"

Source: Global and Planetary Change
Authors: Ricardo L.Silva et al.
DOI: 10.1016/j.gloplacha.2019.103058


Read the full article here.


Defining CO2 and O2 syndromes of marine biomes in the Anthropocene

Abstract.

"Research efforts have intensified to foresee the prospects for marine biomes under climate change and anthropogenic drivers over varying temporal and spatial scales. Parallel with these efforts is the utilization of terminology, such as ‘ocean acidification’ and ‘ocean deoxygenation’, that can foster rapid comprehension of complex processes driving carbon dioxide (CO2) and oxygen (O2) concentrations in the global ocean and thus, are now widely used in discussions within and beyond academia. [...]"

Source: Global Change Biology
Authors: Shannon G. Klein et al.
DOI: 10.1111/gcb.14879

Read the full article here.


Ocean-Atmosphere Observations in Philippine Sea by Moored Buoy

Abstract.

"Offequatorial extension of equatorial buoy arrays such as Tropical Atmosphere and Ocean/Triangle Trans-Ocean Buoy Network (TAO/TRITON) buoy array is required to monitor global and regional climates. On December 3, 2016, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) deployed a moored buoy (Ph buoy) at 13°N, 137° E in the Philippine Sea and are measuring temperature, salinity, and dissolved oxygen concentration from the sea surface to 300 m and atmospheric parameters. [...]"

Source: MTS/IEEE Kobe Techno-Oceans (OTO), 2018 OCEANS
Authors: Akira Nagano  et al.
DOI: 10.1109/OCEANSKOBE.2018.8558886

Read the full article here.


Using machine learning to understand climate change

"Methane is a potent greenhouse gas that is being added to the atmosphere through both natural processes and human activities, such as energy production and agriculture.

To predict the impacts of human emissions, researchers need a complete picture of the atmosphere’s methane cycle. They need to know the size of the inputs—both natural and human—as well as the outputs. They also need to know how long methane resides in the atmosphere.

To help develop this understanding, Tom Weber, an assistant professor of earth and environmental sciences at the University of Rochester; undergraduate researcher Nicola Wiseman ’18, now a graduate student at the University of California, Irvine; and their colleague Annette Kock at the GEOMAR Helmholtz Centre for Ocean Research in Germany, used data science to determine how much methane is emitted from the ocean into the atmosphere each year.  [...]"

Source: University of Rochester

Read the full article here.


Researchers find global ocean methane emissions dominated by shallow coastal waters

"Methane is a potent greenhouse gas that is being added to the atmosphere through both natural processes and human activities, such as energy production and agriculture.

To predict the impacts of human emissions, researchers need a complete picture of the atmosphere's methane cycle. They need to know the size of the inputs—both natural and human—as well as the outputs. They also need to know how long methane resides in the atmosphere. [...]"

Source: Phys.org

Read the full article here.


Global ocean methane emissions dominated by shallow coastal waters

Abstract.

"Oceanic emissions represent a highly uncertain term in the natural atmospheric methane (CH4) budget, due to the sparse sampling of dissolved CH4 in the marine environment. Here we overcome this limitation by training machine-learning models to map the surface distribution of methane disequilibrium (∆CH4). Our approach yields a global diffusive CH4 flux of 2–6TgCH4yr−1 from the ocean to the atmosphere, after propagating uncertainties in ∆CH4 and gas transfer velocity.  [...]"

Source: Nature Communications
Authors: Thomas Weber, Nicola A. Wiseman & Annette Kock 
DOI: 10.1038/s41467-019-12541-7

Read the full article here.


Deep Atlantic mysteries unveiled in the face of climate change

"ATLAS is one of these projects you can’t do justice to in a single-page article. For over 3.5 years now, a consortium of multinational industries, SMEs, governments and academia have been sailing across the Atlantic to assess its deep-sea ecosystems. In doing so, they’ve already managed to deeply enhance our understanding of the consequences of climate change as well as inform the development of better management policies and practices. [...]"

Source: Cordis

Read the full article here.


The IPCC oceans report is a wake-up call for policymakers

"The importance of the ocean in climate regulation is enormous—yet undervalued. The ocean is estimated to have absorbed 93 percent of the excess heat generated by human activities since the 1970s, acting as a buffer against the global warming we've seen to date. The majority of the global carbon cycle circulates through the ocean, through marine food-webs and other processes, and carbon is locked-away in coastal and marine habitats and deep in ocean sediments. Coastal ecosystems alone sequester more carbon than terrestrial forest per unit area. [...]"

Source: Phys.org

Read the full article here.


To solve climate change, remember the ocean

"More than two-thirds of the planet is covered by ocean, but these waters have not received their due in terms of research dollars or public attention. That means the dangers that the seas face from climate change — and the solutions that they offer — are often overlooked. [...]"

Source: Nature
Authors: Janis Searles Jones
DOI: 10.1038/d41586-019-02832-w

Read the full article here.


Ocean phosphorus inventory: large uncertainties in future projections on millennial timescales and their consequences for ocean deoxygenation

Abstract.

"Previous studies have suggested that enhanced weathering and benthic phosphorus (P) fluxes, triggered by climate warming, can increase the oceanic P inventory on millennial timescales, promoting ocean productivity and deoxygenation. In this study, we assessed the major uncertainties in projected P inventories and their imprint on ocean deoxygenation using an Earth system model of intermediate complexity for the same business-as-usual carbon dioxide (CO2) emission scenario until the year 2300 and subsequent linear decline to zero emissions until the year 3000. [...]"

Source: Earth System Dynamics
Authors: Tronje P. Kemena et al.
DOI: 10.5194/esd-10-539-2019

Read the full article here.


A Synthesis of Opportunities for Applying the Telecoupling Framework to Marine Protected Areas

Abstract.

"The world’s oceans face unprecedented anthropogenic threats in the globalized era that originate from all over the world, including climate change, global trade and transportation, and pollution. Marine protected areas (MPAs) serve important roles in conservation of marine biodiversity and ecosystem resilience, but their success is increasingly challenged in the face of such large-scale threats. [...]"

Source: Sustainability
Authors: Vanessa Hull et al.
DOI: 10.3390/su11164450

Read the full article here.


Study tests resilience of the Salish Sea to climate change impacts

"What will the ecology of the Salish Sea look like in the year 2095?

It's an important question for millions of people who live along and near the shores of this intricate, interconnected network of coastal waterways, inlets, bays, and estuaries that encompasses Puget Sound in Washington state and the deep waters of southwest British Columbia. A research team from PNNL found that the inner Salish Sea is resilient, and that future response to climate change—while significant—will be less severe than the open ocean. [...]"

Source: phys.org

Read the full article here.


High-resolution underwater laser spectrometer sensing provides new insights into methane distribution at an Arctic seepage site

Abstract.

"Methane (CH4) in marine sediments has the potential to contribute to changes in the ocean and climate system. Physical and biochemical processes that are difficult to quantify with current standard methods such as acoustic surveys and discrete sampling govern the distribution of dissolved CH4 in oceans and lakes. [...]"

Source: Ocean Science
Authors: Pär Jansson et al. 
DOI: 10.5194/os-15-1055-2019

Read the full article here.


Subseafloor life and its biogeochemical impacts

Abstract.

"Subseafloor microbial activities are central to Earth’s biogeochemical cycles. They control Earth’s surface oxidation and major aspects of ocean chemistry. They affect climate on long timescales and play major roles in forming and destroying economic resources. In this review, we evaluate present understanding of subseafloor microbes and their activities, identify research gaps, and recommend approaches to filling those gaps. [...]"

Source: Nature Communications
Authors: Steven D’Hondt et al.
DOI: 10.1038/s41467-019-11450-z

Read the full article here.


Uncovering mechanisms of global ocean change effects on the Dungeness crab (Cancer magister) through metabolomics analysis

Abstract.

"The Dungeness crab is an economically and ecologically important species distributed along the North American Pacific coast. To predict how Dungeness crab may physiologically respond to future global ocean change on a molecular level, we performed untargeted metabolomic approaches on individual Dungeness crab juveniles reared in treatments that mimicked current and projected future pH and dissolved oxygen conditions. [...]"

Source: Scientific Reports
Authors: Shelly A. Trigg et al.
DOI: 10.1038/s41598-019-46947-6

Read the full article here.


Scientists, students to conduct first live, interactive public broadcasts from arctic ocean

"A team of natural and social scientists, supported by 25 post-secondary students from the U.S. and Canada, will study vital signs of a rapidly changing Arctic Ocean this summer, and offer the public a chance to share the experience in real time.

The innovative, 18-day Northwest Passage Project research expedition will depart on July 18 from the U.S. Air Base in Thule, Greenland, aboard the Swedish Icebreaker Oden, returning to Thule August 4 after a 2,000 nautical mile voyage through the Northwest Passage [...]"

Source: EurekAlert!

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Observing an anticyclonic eddy in the South China Sea using multiple underwater gliders

Abstract.

"Mesoscale eddies, as a considerable contributor to the transport of ocean heat, dissolved oxygen and other biochemical tracers, have an important influence on the distribution of marine resources and global climate change. The purpose of this research is to capture the high variability of an anticyclonic eddy in South China Sea to observe its thermohaline vertical structure in different transections. [...]"

Source: OCEANS 2018 MTS/IEEE Charleston
Authors: Shufeng Li et al.
DOI: 10.1109/OCEANS.2018.8604623

Read the full article here 


The far-future ocean: Warm yet oxygen-rich

"The oceans are losing oxygen. Numerous studies based on direct measurements in recent years have shown this. Since water can dissolve less gas as temperatures rise, these results were not surprising. In addition to global warming, factors such as eutrophication of the coastal seas also contribute to the ongoing deoxygenation. [...]"

Source: Phys.org

Read the full article here.


Loss of fixed nitrogen causes net oxygen gain in a warmer future ocean

Abstract.

"Oceanic anoxic events have been associated with warm climates in Earth history, and there are concerns that current ocean deoxygenation may eventually lead to anoxia. Here we show results of a multi-millennial global-warming simulation that reveal, after a transitory deoxygenation, a marine oxygen inventory 6% higher than preindustrial despite an average 3 °C ocean warming. [...]"

Source: Nature Communications
Authors: Andreas Oschlies et al.
DOI: 10.1038/s41467-019-10813-w

Read the full article here.


Will giant polar amphipods be first to fare badly in an oxygen-poor ocean? Testing hypotheses linking oxygen to body size

Abstract.

"It has been suggested that giant Antarctic marine invertebrates will be particularly vulnerable to declining O2 levels as our ocean warms in line with current climate change predictions. Our study provides some support for this oxygen limitation hypothesis, with larger body sizes being generally more sensitive to O2 reductions than smaller body sizes. [...]"

Source: Philosophical Transactions of the Royal Society B
Authors: John I. Spicer  and Simon A. Morley
DOI: 10.1098/rstb.2019.0034

Read the full article here.


The complex fate of Antarctic species in the face of a changing climate

"Researchers have presented support for the theory that marine invertebrates with larger body size are generally more sensitive to reductions in oxygen than smaller animals, and so will be more sensitive to future global climate change. However, evolutionary innovation can to some extent offset any respiratory disadvantages of large body size. [...]"

Source: Science Daily / University of Plymouth

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.


Multi-faceted particle pumps drive carbon sequestration in the ocean

Abstract.

"The ocean’s ability to sequester carbon away from the atmosphere exerts an important control on global climate. The biological pump drives carbon storage in the deep ocean and is thought to function via gravitational settling of organic particles from surface waters. However, the settling flux alone is often insufficient to balance mesopelagic carbon budgets or to meet the demands of subsurface biota. [...]"

Source: Nature
Authors: Philip W. Boyd et al.
DOI: 10.1038/s41586-019-1098-2

Read the full article here.


Uncovering mechanisms of global ocean change effects on the Dungeness crab (Cancer magister) through metabolomics analysis

Abstract.

"The Dungeness crab is an economically and ecologically important species distributed along the North American Pacific coast. To predict how Dungeness crab may physiologically respond to future global ocean change on a molecular level, we performed untargeted metabolomic approaches on individual Dungeness crab juveniles reared in treatments that mimicked current and projected future pH and dissolved oxygen conditions. We found 94 metabolites and 127 lipids responded in a condition-specific manner, with a greater number of known compounds more strongly responding to low oxygen than low pH exposure. [...]"

Source: bioRxiv
Authors: Shelly A. Trigg et al.
DOI: 10.1101/574798

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.


Consequences of climate-induced low oxygen conditions for commercially important fish

Abstract.

"Oxygen availability is key in determining habitat suitability for marine fish. As a result of climate change, low oxygen conditions are predicted to occur more frequently and over a greater geographic extent. Studies assessing the long-term chronic effects and impacts for commercially important fish are rare. To assess the potential effects of climate-induced low oxygen on fisheries, physiological data, such as critical thresholds, derived from laboratory experiments on 5 commercial fish species were integrated with hindcast and future oxygen projections from the hydrodynamic-biogeochemical model GETM-ERSEM. [...]"

Source: Marine Ecology Progress Series (2017)
Authors: Bryony L. Townhill et al.
DOI: 10.3354/meps12291

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.


Effects of Higher CO2 and Temperature on Exopolymer Particle Content and Physical Properties of Marine Aggregates

Abstract.

"We investigated how future ocean conditions, and specifically the interaction between temperature and CO2, might affect marine aggregate formation and physical properties. Initially, mesocosms filled with coastal seawater were subjected to three different treatments of CO2 concentration and temperature: (1) 750 ppm CO2, 16°C, (2) 750 ppm CO2, 20°C, and (3) 390 ppm CO2, 16°C. Diatom-dominated phytoplankton blooms were induced in the mesocosms by addition of nutrients. [...]"

Source: Frontiers in Marine Science
Authors: Carolina Cisternas-Novoa et al.
DOI: 10.3389/fmars.2018.00500

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.


Evolving paradigms in biological carbon cycling in the ocean

Abstract.

"Carbon is a keystone element in global biogeochemical cycles. It plays a fundamental role in biotic and abiotic processes in the ocean, which intertwine to mediate the chemistry and redox status of carbon in the ocean and the atmosphere. The interactions between abiotic and biogenic carbon (e.g. CO2, CaCO3, organic matter) in the ocean are complex, and there is a half-century-old enigma about the existence of a huge reservoir of recalcitrant dissolved organic carbon (RDOC) that equates to the magnitude of the pool of atmospheric CO2. The concepts of the biological carbon pump (BCP) and the microbial loop (ML) shaped our understanding of the marine carbon cycle.  [...]"

Source: National Science Review
Authors: Chuanlun Zhang et al.
DOI: 10.1093/nsr/nwy074

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.

 


Finding forced trends in oceanic oxygen

Abstract.

"Anthropogenically forced trends in oceanic dissolved oxygen are evaluated in Earth system models in the context of natural variability. A large ensemble of a single Earth system model is used to clearly identify the forced component of change in interior oxygen distributions and to evaluate the magnitude of this signal relative to noise generated by internal climate variability. The time of emergence of forced trends is quantified on the basis of anomalies in oxygen concentrations and trends. [...]"

Source: Global Biogeochemical Cycles
Authors: Matthew C. Long, Curtis Deutsch and Taka Ito
DOI: 10.1002/2015GB005310 

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.


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.


Manifestation, Drivers, and Emergence of Open Ocean Deoxygenation

Abstract.

"Oxygen loss in the ocean, termed deoxygenation, is a major consequence of climate change and is exacerbated by other aspects of global change. An average global loss of 2% or more has been recorded in the open ocean over the past 50–100 years, but with greater oxygen declines in intermediate waters (100–600 m) of the North Pacific, the East Pacific, tropical waters, and the Southern Ocean. Although ocean warming contributions to oxygen declines through a reduction in oxygen solubility and stratification effects on ventilation are reasonably well understood, it has been a major challenge to identify drivers and modifying factors that explain different regional patterns, especially in the tropical oceans. [...]"

Source: Annual Review of Marine Science
Author: L. Levin
DOI: 10.1146/annurev-marine-121916-063359

Read the full article here.


Investigator Voyage to Address Puzzle of Southern Ocean Current

"An IMAS-led voyage on the Marine National Facility research vessel Investigator today sailed from Hobart with scientists aiming to solve a Southern Ocean puzzle with important ramifications for the global climate.

The researchers will survey a ‘standing meander’ south of Tasmania that they hope will help them to understand why the east-flowing Antarctic Circumpolar Current (ACC) has remained constant despite westerly winds strengthening by 20% over the last two decades. [...]"

Source: IMAS

Read the full article here.


Global-ocean redox variations across the Smithian-Spathian boundary linked to concurrent climatic and biotic changes

Abstract.

"The Smithian-Spathian boundary (SSB) was an interval characterized by a major global carbon cycle perturbation, climatic cooling from a middle/late Smithian boundary hyperthermal condition, and a major setback in the recovery of marine necto-pelagic faunas from the end-Permian mass extinction. Although the SSB has been linked to changes in oceanic redox conditions, key aspects of this redox variation (e.g., duration, extent, and triggering mechanisms) and its relationship to coeval climatic and biotic changes remain unresolved. [...]"

Source: Earth-Science Reviews
Authors: Feifei Zhang et al.
DOI: 10.1016/j.earscirev.2018.10.012

Read the full article here.


The impact of ocean acidification on the byssal threads of the blue mussel (Mytilus edulis)

Abstract.

"Blue mussel (Mytilus edulis) produce byssal threads to anchor themselves to the substrate. These threads are always exposed to the surrounding environmental conditions. Understanding how environmental pH affects these threads is crucial in understanding how climate change can affect mussels. This work examines three factors (load at failure, thread extensibility, and total thread counts) that indicate the performance of byssal threads as well as condition index to assess impacts on the physiological condition of mussels held in artificial seawater acidified by the addition of CO2. [...]"

Source: PLOS ONE
Authors: Grant Dickey et al.
DOI: 10.1371/journal.pone.0205908

Read the full article here.


(2010) The Growing Human Footprint on Coastal and Open-Ocean Biogeochemistry

Abstract.

"Climate change, rising atmospheric carbon dioxide, excess nutrient inputs, and pollution in its many forms are fundamentally altering the chemistry of the ocean, often on a global scale and, in some cases, at rates greatly exceeding those in the historical and recent geological record. Major observed trends include a shift in the acid-base chemistry of seawater, reduced subsurface oxygen both in near-shore coastal water and in the open ocean, rising coastal nitrogen levels, and widespread increase in mercury and persistent organic pollutants. [...]"

Source: Science
Author: Scott C. Doney
DOI: 10.1126/science.1185198

Read the full article here.


Spatial congruence between multiple stressors in the Mediterranean Sea may reduce its resilience to climate impacts

Abstract.

"Climate impacts on marine ecosystems may be exacerbated by other, more local stressors interacting synergistically, such as pollution and overexploitation of marine resources. The reduction of these human stressors has been proposed as an achievable way of retaining ecosystems within a “safe operating space” (SOS), where they remain resilient to ongoing climate change. However, the operability of an SOS requires a thorough understanding of the spatial distribution of these climate and human impacts. [...]"

Source: Scientific Reports
Authors: Francisco Ramírez et al.
DOI: 10.1038/s41598-018-33237-w

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Last interglacial ocean changes in the Bahamas: climate teleconnections between low and high latitudes

Abstract.

"Paleorecords and modeling studies suggest that instabilities in the Atlantic Meridional Overturning Circulation (AMOC) strongly affect the low-latitude climate, namely via feedbacks on the Atlantic Intertropical Convergence Zone (ITCZ). Despite the pronounced millennial-scale overturning and climatic variability documented in the subpolar North Atlantic during the last interglacial period (MIS 5e), studies on cross-latitudinal teleconnections remain very limited. This precludes a full understanding of the mechanisms controlling subtropical climate evolution across the last warm cycle. [...]"

Source: Climate of the Past
Authors: Anastasia Zhuravleva and Henning A. Bauch
DOI: 10.5194/cp-14-1361-2018

Read the full article here.


Projected amplification of food web bioaccumulation of MeHg and PCBs under climate change in the Northeastern Pacific

Abstract.

"Climate change increases exposure and bioaccumulation of pollutants in marine organisms, posing substantial ecophysiological and ecotoxicological risks. Here, we applied a trophodynamic ecosystem model to examine the bioaccumulation of organic mercury (MeHg) and polychlorinated biphenyls (PCBs) in a Northeastern Pacific marine food web under climate change. We found largely heterogeneous sensitivity in climate-pollution impacts between chemicals and trophic groups. Concentration of MeHg and PCBs in top predators, including resident killer whales, is projected to be amplified by 8 and 3%, respectively, by 2100 under a high carbon emission scenario (Representative Concentration Pathway 8.5) relative to a no-climate change control scenario. [...]"

Source: Scientific Reports
Authors: Juan José Alava et al.
DOI: 10.1038/s41598-018-31824-5

Read the full article here.


Decomposing the effects of ocean environments on predator–prey body-size relationships in food webs

Abstract.

"Body-size relationships between predators and their prey are important in ecological studies because they reflect the structure and function of food webs. Inspired by studies on the impact of global warming on food webs, the effects of temperature on body-size relationships have been widely investigated; however, the impact of environmental factors on body-size relationships has not been fully evaluated because climate warming affects various ocean environments. Thus, here, we comprehensively investigated the effects of ocean environments and predator–prey body-size relationships by integrating a large-scale dataset of predator–prey body-size relationships in marine food webs with global oceanographic data. We showed that various oceanographic parameters influence prey size selection. [...]"

Source: Royal Society Open Science
Authors: Tomoya Dobashi, Midori Iida, Kazuhiro Takemoto
DOI: 10.1098/rsos.180707

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.


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.


Changing storminess and global capture fisheries

"Climate change-driven alterations in storminess pose a significant threat to global capture fisheries. Understanding how storms interact with fishery social-ecological systems can inform adaptive action and help to reduce the vulnerability of those dependent on fisheries for life and livelihood."

Source: Nature Climate Change
Authors: Nigel C. Sainsbury et al.
DOI: 10.1038/s41558-018-0206-x

Read the full article here.


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