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We document dense water formation (DWF) throughout the Adriatic shelf and coastal area in January/February 2012, resulting in record-breaking densities observed during and after the event. The unprecedented dense water generation was preconditioned by a dry and warm year which resulted in a significant reduction of coastal freshwaters, superimposed on a long-term basin-wide salinity increase. The final event that triggered the DWF was an extended period of cold weather with strong and severe winds. Record-breaking potential density anomalies (above 30 kgm-3) were measured at several DWF sites. Accumulated surface net heat and water losses in some coastal regions exceeded 1.5GJm-2 and 250 kgm-2 over 21 days, respectively. Excessiveness, importance of shelf-type DWF, effects on the thermohaline circulation and deep aquatic systems, and connection with climate change are discussed. [ABSTRACT FROM AUTHOR]

Eastern Boundary Upwelling Systems (EBUS) are highly productive ocean regions. Yet, substantial differences in net primary production (NPP) exist within and between these systems for reasons that are still not fully understood. Here, we explore the leading physical processes and environmental factors controlling NPP in EBUS through a comparative study of the California, Canary, Benguela, and Humboldt Current systems. The identification of NPP drivers is done with the aid of an artificial neural network analysis based on self-organizing-maps (SOMs). We show that in addition to the expected NPP enhancing effect of stronger alongshore wind, three factors have an inhibiting effect: (1) strong eddy activity, (2) narrow continental shelf, and (3) deep mixed layer. The co-variability of these 4 drivers defines in the context of the SOM a continuum of 100 patterns of NPP regimes in EBUS. These are grouped into 4 distinct classes using a Hierarchical Agglomerative Clustering (HAC) method. Our objective classification of EBUS reveals important variations of NPP regimes within each of the four EBUS, particularly in the Canary and Benguela Current systems. Our results show that the Atlantic EBUS are generally more productive and more sensitive to upwelling favorable winds because of a weaker factors inhibiting NPP. Perturbations of alongshore winds associated with climate change may therefore lead to contrasting biological responses in the Atlantic and the Pacific EBUS. [ABSTRACT FROM AUTHOR]

Recent observations suggest that El Niño–Southern Oscillation (ENSO) impacts basal melting of West Antarctic ice shelves, yet sparse ocean observations limit our understanding of the associated processes. Here we investigate how ENSO events modulate subsurface West Antarctic shelf temperatures using high‐resolution global ocean‐sea ice model simulations. During El Niño, the subsurface shelf warming between 150 m and the shelf bottom can be up to 0.5°C in front of ice shelves. This warming arises from a weaker Amundsen Sea Low (ASL) and weaker coastal easterlies that reduce on‐shelf Ekman transport of cold surface waters, enabling enhanced transport of warm Circumpolar Deep Water (CDW) onto the shelf. A largely opposite response occurs during La Niña, with a stronger ASL and stronger Ekman transport that results in less cross‐shelf CDW transport and cooling in the subsurface. These findings have implications for interpreting basal melting on interannual to decadal time‐scales in West Antarctica. Plain Language Summary: El Niño‐Southern Oscillation (ENSO) is the Earth's dominant year‐to‐year climate variation. The impacts of its two phases, El Niño and La Niña, extend from the tropics to Antarctica through atmospheric waves. Past studies have suggested that West Antarctic ice shelves melt more during El Niño because of warmer ocean waters at the ice shelf bases. However, oceanic changes during El Niño lead to warming on the shelf near the ice which is difficult to isolate. That is because ENSO is only one of many drivers that impact shelf water temperatures. In this work, we simulate isolated ENSO events using an ocean circulation model. We show that during El Niño, the on‐shelf flow of cold surface waters in West Antarctica, driven by coastal easterly winds, is reduced because the winds weaken. To balance out this mass deficit at the surface, more warm CDW flows onto the continental shelf below. During La Niña, we see a largely opposite response. Stronger coastal easterlies increase the on‐shelf flow of cold surface waters and less CDW is flowing onto the shelf. Our results show the link between ENSO and mass loss of the West Antarctic ice shelves and ice sheet. Key Points: Ocean‐sea ice model simulations of El Niño and La Niña events illustrate how they modulate West Antarctic shelf temperaturesEl Niño weakens coastal easterlies, reduces on‐shelf Ekman flow of cold waters, increasing cross‐shelf flow of warm Circumpolar Deep Water (CDW)The La Niña shelf circulation response is largely opposite and reduces cross‐shelf transport of warm CDW [ABSTRACT FROM AUTHOR]

Development of the continental shelf has accelerated significantly as nations around the world seek to harness offshore renewable energy. Many areas marked for development align with submerged palaeolandscapes. Poorly understood and difficult to protect, these vulnerable, prehistoric landscapes provide specific challenges for heritage management. Indeed, there now appears to be a schism between what underwater cultural heritage policy intends and what it is achieving in practice. Shortcomings in international and national legislature ensures that large parts of the continental shelf, including areas under development, may have little or no legal protection. Increasingly impacted by extensive development, these unique cultural landscapes are ever more at risk. However, heritage challenges posed by such development also create opportunities. An immense amount of data is being generated by development, and there is an opportunity to establish broader cooperative relationships involving industrial stakeholders, national curators, government bodies, and heritage professionals. As a matter of urgency, the archaeological community must better engage with the offshore sector and development process. If achieved, we may revolutionise our knowledge of submerged prehistoric settlement and land use. Otherwise, our capacity to reconstruct prehistoric settlement patterns, learn from past climate change, or simply manage what are among the best-preserved postglacial landscapes globally may be irreparably undermined. [ABSTRACT FROM AUTHOR]

In this paper, we investigate changes in the wave climate of the west-European shelf seas under global warming scenarios. In particular, climate change wind fields corresponding to the present (control) time-slice 1961-2000 and the future (scenario) time-slice 2061-2100 are used to drive a wave generation model to produce equivalent control and scenario wave climate. Yearly and seasonal statistics of the scenario wave climates are compared individually to the corresponding control wave climate to identify relative changes of statistical significance between present and future extreme and prevailing wave heights. Using global, regional and linked global-regional wind forcing over a set of nested computational domains, this paper further demonstrates the sensitivity of the results to the resolution and coverage of the forcing. It suggests that the use of combined forcing from linked global and regional climate models of typical resolution and coverage is a good option for the investigation of relative wave changes in the region of interest of this study. Coarse resolution global forcing alone leads to very similar results over regions that are highly exposed to the Atlantic Ocean. In contrast, fine resolution regional forcing alone is shown to be insufficient for exploring wave climate changes over the western European waters because of its limited coverage. Results obtained with the combined global-regional wind forcing showed some consistency between scenarios. In general, it was shown that mean and extreme wave heights will increase in the future only in winter and only in the southwest of UK and west of France, north of about 44-45° N. Otherwise, wave heights are projected to decrease, especially in summer. Nevertheless, this decrease is dominated by local wind waves whilst swell is found to increase. Only in spring do both swell and local wind waves decrease in average height. [ABSTRACT FROM AUTHOR]

The transport of water masses with ocean circulation is a key component of the global climate system. In this context, the Filchner Trough in the southern Weddell Sea is critical, as it is a hotspot for the cross-shelf-break exchange of Dense Shelf Water and Warm Deep Water. We present results from Lagrangian particle tracking experiments in a global-ocean–sea-ice model (FESOM-1.4) which includes ice-shelf cavities and has eddy-permitting resolution on the southern Weddell Sea continental shelf. With backward and forward experiments, we assess changes between a present-day and a future (SSP5-8.5) time slice in the origin of waters reaching the Filchner Ice Shelf front and the fate of waters leaving it. We show that particles reaching the ice-shelf front from the open ocean originate from 173 % greater depths by 2100 (median; 776 m as compared to 284 m for the present day), while waters leaving the cavity towards the open ocean end up at 35 % shallower depths (550 m as compared to 850 m for the present day). Pathways of water leaving the continental shelf increasingly occur in the upper ocean, while the on-shelf flow of waters that might reach the ice-shelf cavity, i.e., at deeper layers, becomes more important by 2100. Simultaneously, median transit times between the Filchner Ice Shelf front and the continental shelf break decrease (increase) by 6 (9.5) months in the backward (forward) experiments. In conclusion, our study demonstrates the sensitivity of regional circulation patterns in the southern Weddell Sea to ongoing climate change, with direct implications for ice-shelf basal melt rates and local ecosystems. [ABSTRACT FROM AUTHOR]

Sandy shorelines occupy ca. 80% of the coast of Mozambique, South Africa and Namibia. A geomorphological classification of sandy shorelines in the subcontinent identifies twelve major categories in four sub-regional coastal systems. The behaviour of each of the major shoreline types under rising sea level is outlined based on geological principles together with observations of former shorelines preserved onshore and on the continental shelf. Human adaptation strategies regarding shoreline change involve a binary choice (hold the shoreline in place or permit it to fluctuate) and these exert an equally important control on sandy shoreline response in the medium term as does sea-level rise itself. It is anticipated that densely urbanised sandy shorelines will be stabilised by coastal defences involving both capital works and ongoing maintenance that will be accompanied by deterioration and ultimate loss/replacement of the natural ecosystem. In contrast, currently undeveloped, natural shorelines will be permitted to adjust and will, as a consequence, survive and continue to deliver ecosystem services. The major challenge for climate-change adaptation lies in those lightly urbanised coastal areas where relatively small numbers of property owners may be, or perceive themselves to be, at risk of economic loss from shoreline change. In such cases the choice is between preserving those property interests (through sea defences) and preserving the sandy shoreline and its human and ecosystem services (via retreat). [ABSTRACT FROM AUTHOR]

Osborne, P.D. and Forest, A., 2016. Sediment dynamics from coast to slope - Southern Canadian Beaufort Sea. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 537-541. Coconut Creek (Florida), ISSN 0749-0208. Profound changes in cross-shelf sediment fluxes are anticipated in coming decades in the southern Canadian Beaufort Sea where an accelerated increase in temperature could lead to large changes in Arctic river hydrology and coastal-marine geomorphologic processes. In the past decade sediment exported to the Beaufort Shelf has increased while sea level pressure has increased accelerating the Beaufort Gyre, strengthening coastal upwelling and expanding the Mackenzie River plume offshore. Sea-ice extent has decreased while storminess has increased increasing wave action, coastal downwelling, current surge and resuspension and transport on the shoreface and shelf. This paper investigates mechanisms, quantities and rates of sediment transport operating in this cold continental shelf-slope environment. Past studies from more than 2 decades of research are compared with recent measurements to develop improved estimates of sediment sources, pathways, fate and fluxes across the shelf and slope. In particular, we explore connections between data from a long term mooring observatory deployed over the continental shelf and slope during the ArcticNet-Industry Partnership (2009-2011) and Beaufort Regional Environmental Assessment (BREA 2011-2015) to those acquired in studies focusing on nearshore and shoreface. Sediment fluxes from the Mackenzie River and erosion of permafrost coasts are compared with outer shelf-slope measurements of settling particles and near-bottom fluxes. In turn, the role of atmospheric and cryospheric processes in forcing sediment transfer from coast to slope is investigated to assess system response to changing climate and evaluate implications for marine hydrocarbon resource development along the continental margin of the Arctic Ocean. [ABSTRACT FROM AUTHOR]

Tipping points in the Earth system describe critical thresholds beyond which a single component, part of the system, or the system as a whole changes from one stable state to another. In the present-day Southern Ocean, the Weddell Sea constitutes an important dense-water formation site, associated with efficient deep-ocean carbon and oxygen transfer and low ice-shelf basal melt rates. Here, a regime shift will occur when continental shelves are continuously flushed with warm, oxygen-poor offshore waters from intermediate depth, leading to less efficient deep-ocean carbon and oxygen transfer and higher ice-shelf basal melt rates. We use a global ocean–biogeochemistry model including ice-shelf cavities and an eddy-permitting grid in the southern Weddell Sea to address the susceptibility of this region to such a system change for four twenty-first-century emission scenarios. Assessing the projected changes in shelf–open-ocean density gradients, bottom-water properties, and on-shelf heat transport, our results indicate that the Weddell Sea undergoes a regime shift by 2100 in the highest-emission scenario, SSP5–8.5, but not yet in the lower-emission scenarios. The regime shift is imminent by 2100 in the scenarios SSP3–7.0 and SSP2–4.5, but avoidable under the lowest-emission scenario SSP1–2.6. While shelf-bottom waters freshen and acidify everywhere, bottom waters in the Filchner Trough undergo accelerated warming and deoxygenation following the system change, with implications for local ecosystems and ice-shelf basal melt. Additionally, deep-ocean carbon and oxygen transfer decline, implying that the local changes ultimately affect ocean circulation, climate, and ecosystems globally. [ABSTRACT FROM AUTHOR]

Wind energy refers to the process of creating electricity using the wind, or air flows that occur naturally in the earth's atmosphere. Considered as a free and low-carbon energy, wind energy source has handy the attention of decision makers around the world. Wind energy has the possibilities of reducing the worlds dependence on fossil fuels and has a very huge potential to impart sustainable development of both climate and energy. This paper is focusing on the wind energy potentials of the Atlantic Outer Continental Shelf Region of the United States, as a strategic location to develop wind farms that would help mitigate climate change. We used a GIS based approach in identifying suitable locations for wind farms and assessing wind energy potentials as a mitigation to climate change by using a weighted overlay of geospatial layers corresponding to these criteria. Results showed that a wind turbine runs practically emissions-free for 20 years, a viable alternative to burning polluting fossil fuels that offset all emissions within the first 6 months of operation. The Atlantic OCS Region present us with enormous wind energy potentials. Findings in this paper projects that from 2020, wind power alone would save 9.25 billion tons of CO2 every year. On average, each kWh of wind power generated would avoid 600 grams of CO2 (Global Wind Energy Council). Renewable energy would help mitigate climate change in an excellent way. However, we need sustainability in order to ensure a sustainable future for generations to come. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the effect of future sea-level rise (SLR) on the tides of the northwest European Continental Shelf. The European shelf tide is dominated by semidiurnal constituents. This study therefore focuses primarily on the changes in the M2 tidal constituent and the spring and neap tidal conditions. The validated operational Dutch Continental Shelf Model is run for the present day sea-level as well as 2 and 10m SLR scenarios. The M2 tidal amplitude responds to SLR in a spatially non-uniform manner, with substantial amplitude increases and decreases in both scenarios. The M2 tidal response is non-linear between 2 and 10m with respect to SLR, particularly in the North Sea. Under the 2m SLR scenario the M2 constituent is particularly responsive in the resonant areas of the Bristol Channel and Gulf of St. Malo (with large amplitude decreases) and in the southeastern German Bight and Dutch Wadden Sea (with large amplitude increases). Changes in the spring tide are generally greater still than those in the M2 or neap tides. With 2m SLR the spring tidal range increases up to 35cm at Cuxhaven and decreases up to −49cm at St. Malo. Additionally the changes in the shallow water tides are larger than expected. With SLR the depth, wave speed and wave length (tidal resonance characteristics) are increased causing changes in near resonant areas. In expansive shallow areas SLR causes reduced energy dissipation by bottom friction. Combined these mechanisms result in the migration of the amphidromes and complex patterns of non-linear change in the tide with SLR. Despite the significant uncertainty associated with the rate of SLR over the next century, substantial alterations to tidal characteristics can be expected under a high end SLR scenario. Contrary to existing studies this paper highlights the importance of considering the modification of the tides by future SLR. These substantial future changes in the tides could have wide reaching implications; including for example, correctly calculating design level requirements for flood defences, the availability of tidal renewable energy and dredging requirements. [Copyright &y& Elsevier]

Abstract: According to the forecast of the International Energy Agency (IEA), CCS has the potential to reduce carbon dioxide emissions and could contribute to 19% of global carbon dioxide mitigation by 2050. Korean government recently announced that Korea has set its voluntary 2020 emissions reduction target to a 30% reduction from its forecast under a ”business as usual” scenario, which is equivalent to 4% less than the 594 million tons of carbon that was emitted in 2005. CCS is included to achieve this target. This paper first explains the CO2 storage potential both in onshore and offshore areas in Korea. While onshore sedimentary basins seem to have unfavorable physical properties such as porosity and permeability, offshore sedimentary basins exhibit very good physical properties in sand thickness and porosity. In order to implement CCS project at the scale needed to achieve a meaningful reduction of carbon dioxide emissions, the knowledge of the available CO2 storage capacity obtained by detailed matching of large stationary CO2 sources with geological storage sites is required. Most CCS programs in Korea, however, are not integrated with capture and storage projects. This paper considers the feasibility of CO2 capture and storage in Korea and shows several conceptual business models for CCS projects with the recent E&P activities in the continental shelf. [Copyright &y& Elsevier]

This paper presents an overview of the evolution of the Nile deep-sea turbidite system during the last 200 kyr, over a series of glacial to interglacial cycles. Six individual deep-sea fans were identified from an extensive field data set. Each fan comprises a canyon, channel system and terminal lobes. Two of these fan systems were possibly active at the same time, at least during some periods. Large-scale slope failures destroyed channel segments and caused the formation of new submarine fan systems. These slope failures thus played an important role in the overall evolution of the turbidite system. During the last glacial maximum ( ca 25 to 14·8 ka) the central and eastern parts of the Nile deep-sea turbidite system were relatively inactive. This inactivity corresponds to a lowstand in sea-level, and a period of arid climate and relatively low sediment discharge from the Nile fluvial system. Rapid accumulation of fluvial flood-derived deposits occurred across the shallower part of the submarine delta during sea-level rise between ca 14·8 and 5 ka. The most recent deep-sea channel–lobe system was very active during this period of rising sea-level, which is also associated with a wetter continental climate and increased sediment and water discharge from the Nile. Increased sediment deposition in shallower water areas led to occasional large-scale slope failure. The Nile deep-sea turbidite system was largely inactive after ca 5 ka. This widespread inactivity is due to retreat of the coastline away from the continental shelf break, and to a more arid continental climate and reduced discharge of sediment from the Nile. The Nile deep-sea turbidite system may be more active during periods of rising and high sea-level associated with wetter climates, than during lowstands, and may rapidly become largely inactive during highstands in sea-level coupled with arid periods. These acute responses to climate change have produced sedimentary/stratigraphic features that diverge from traditional sequence models in their nature and timing. This large-scale sedimentary system responded to monsoon-driven climate change and sea-level change in a system-wide and contemporaneous manner. [ABSTRACT FROM AUTHOR]

The influence of the coastal ocean on global net annual air-sea CO2 fluxes remains uncertain. However, it is well known that air-sea pCO2 disequilibria can be large (ocean pCO2 ranging from ∼400 µatm above atmospheric saturation to ∼250 µatm below) in eastern boundary currents, and it has been hypothesized that these regions may be an appreciable net carbon sink. In addition it has been shown that the high productivity in these regions (responsible for the exceptionally low surface pCO2) can cause nutrients and inorganic carbon to become more concentrated in the lower layer of the water column over the shelf relative to adjacent open ocean waters of the same density. This paper explores the potential role of the winter season in determining the net annual CO2 flux in temperate zone eastern boundary currents, using the results from a box model. The model is parameterized and forced to represent the northernmost part of the upwelling region on the North American Pacific coast. Model results are compared to the few summer data that exist in that region. The model is also used to determine the effect that upwelling and downwelling strength have on the net annual CO2 flux. Results show that downwelling may play an important role in limiting the amount of CO2 outgassing that occurs during winter. Finally data from three distinct regions on the Pacific coast are compared to highlight the importance of upwelling and downwelling strength in determining carbon fluxes in eastern boundary currents and to suggest that other features, such as shelf width, are likely to be important. [ABSTRACT FROM AUTHOR]

Predicting the impact of marine ecosystem warming on the timing and magnitude of phytoplankton production is challenging. For example, warming can advance the progression of stratification thereby changing the availability of nutrients to surface phytoplankton, or influence the surface mixed layer depth, thus affecting light availability. Here, we use a time series of sea surface temperature (SST) and chlorophyll remote sensing products to characterize the response of the phytoplankton community to increased temperature in the Northeast US Shelf Ecosystem. The rate of change in SST was higher in the summer than in winter in all ecoregions resulting in little change in the timing and magnitude of the spring thermal transition compared to a significant change in the autumn transition. Along with little phenological shift in spring thermal conditions, there was also no evidence of a change in spring bloom timing and duration. However, we observed a change in autumn bloom timing in the Georges Bank ecoregion, where bloom initiation has shifted from late September to late October between 1998 and 2020—on average 33 d later. Bloom duration in this ecoregion also shortened from ∼7.5 to 5 weeks. The shortened autumn bloom may be caused by later overturn in stratification known to initiate autumn blooms in the region, whereas the timing of light limitation at the end of the bloom remains unchanged.  These changes in bloom timing and duration appear to be related to the change in autumn thermal conditions and the significant shift in autumn thermal transition. These results suggest that the spring bloom phenology in this temperate continental shelf ecosystem may be more resilient to thermal climate change effects than blooms occurring in other times of the year. [ABSTRACT FROM AUTHOR]

A modelling approach to understand the tsunamigenic potentiality of submarine landslides will provide new perspectives on tsunami hazard threat, mostly in polar margins where global climatic change and its related ocean warming may induce future landslides. Here, we use the L-ML-HySEA (Landslide Multilayer Hyperbolic Systems and Efficient Algorithms) numerical model, including wave dispersion, to provide new insights into factors controlling the tsunami characteristics triggered by the Storfjorden LS-1 landslide (southwestern Svalbard). Tsunami waves, determined mainly by the sliding mechanism and the bathymetry, consist of two initial wave dipoles, with troughs to the northeast (Spitsbergen and towards the continent) and crests to the south (seawards) and southwest (Bear Island), reaching more than 3 m of amplitude above the landslide and finally merging into a single wave dipole. The tsunami wave propagation and its coastal impact are governed by the Storfjorden and Kveithola glacial troughs and by the bordering Spitsbergen Bank, which shape the continental shelf. This local bathymetry controls the direction of propagation with a crescent shape front, in plan view, and is responsible for shoaling effects of amplitude values (4.2 m in trough to 4.3 m in crest), amplification (3.7 m in trough to 4 m in crest) and diffraction of the tsunami waves, as well as influencing their coastal impact times. [ABSTRACT FROM AUTHOR]

Recent improvements in satellite altimetry data correction terms are encouraging studies of the remote sensed sea level anomalies (SLA) progressively closer to the coast and over shallow continental shelves. In this paper we describe and discuss the SLA trend and variability at seasonal and interannual time scales in the southeastern South American continental shelf influenced by the Río de la Plata estuary and the Patos Lagoon fresh waters. The spatio-temporal coverage of the gridded altimetry SLA data allows identify several variability patterns and the associated physical processes. On seasonal time scales, the combination of the solar radiation and wind forcing cycles accounts for up to 98% of the variability. Seasonal variability of the wind is responsible for a difference of up to 16 cm between the southern (Argentinean) Río de la Plata estuary coast and the Uruguayan and southern Brazilian coasts. On interannual time scales, positive/negative SLA anomalies are coherent with El Niño/La Niña events. Finally, a significant positive trend of up to 5 mm yr −1 is found in all the study area except in the region around the Patos Lagoon (Brazil) and part of the Río de la Plata. Besides the local relevance of the results, this study indicates that satellite altimetry data are accurate enough to unveil SLA spatio-temporal patterns close to the coast and over continental shelves in the mentioned time scales. [ABSTRACT FROM AUTHOR]

The Araucaria Plateau is a geomorphological unit that occupies approximately three-quarters of the terrain in the southern region of Brazil. The plateau displays different altitudinal levels (600 to <1400 m a.s.l.) that are locally recognized as remnants of planed surfaces (S8-S1). These surfaces are maintained by basic (S3-S8) and acidic (S1 and S2) volcanic flows from the Neocretaceous period of the Paraná Basin. The largest extent of this plateau is located in a humid subtropical climate zone. Colluvial, colluvial-alluvial, alluvial sediments and paleosols (Ab diagnostic horizons) occur predominantly in S2. The paleosols are located in low-hierarchical-order fossil valleys (first- to fourth-order in Strahler's stream classification) and valley heads, which are referred to as paleovalleys in this paper. We employed these paleosols as stratigraphic level markers of the pedogenesis of the regional Upper Quaternary and propose their importance as records of the paleoenvironmental conditions of the Araucaria Plateau in areas above 1200 m a.s.l. These paleosols were dated by 14C and show ages between 23.8 ± 0.05 kyr BP (28.06-29.08 kyr cal. BP) and 41.16 ± 0.48 kyr BP (44.13-45.58 kyr cal. BP). The calibrated ages are related to Marine Isotope Stage 3 (MIS 3), in which the last period of global warming occurred (approximately 60-25 kyr cal. BP). We integrated the morphological, pedogeochemical, clay fraction mineralogy, micromorphological and δC-13 analyses of five paleosols from S2 to verify the paleoenvironmental conditions of the Araucaria Plateau and its correspondence with the paleoclimatic phenomena that were identified on a global scale during MIS 3 in the Southern Hemisphere. We obtained the following conclusions: a) the properties of paleosols reflect pedological processes that are adjusted to the paleoenvironmental conditions at the end of MIS 3 and the transition to MIS 2 (Last Glacial Maximum); b) aplasmogenic partial acidolysis was the predominant pedogeochemical process during MIS 3; c) during this period, the water regime was sufficiently humid to develop hydromorphic horizons in the valley bottoms of the entire drainage network to the valley heads; d) regional change toward a drier hydric regime occurred in MIS 2, when erosion of the paleosols predominated; and e) in MIS 1 (current Holocene interglacial), burial of the paleosols and relief inversion occurred, which resulted in fossilization of the valleys. [ABSTRACT FROM AUTHOR]

Assessment of zooplankton abundance, distribution, community composition, and temporal variability is critical to understanding the effects of climate variability and change on lower trophic level production and availability for consumption by larger consumers. Zooplankton sampling is performed across the Canadian continental shelf system by Fisheries and Oceans Canada's Atlantic Zone Monitoring Programme (AZMP). Sampling includes semi-monthly to monthly collection of zooplankton using vertical net tows (VNTs) deployed from near-bottom to surface at stations on the central Scotian Shelf (Stn 2, 150 m depth) and Newfoundland Shelf (Stn 27, 175 m depth), and by Continuous Plankton Recorders (CPRs) in the near-surface layers along routes over the Scotian and Newfoundland shelves (0–10 m depth). Here, we compare abundance metrics for 11 copepod taxa collected using both gear types in both regions between 1999 and 2015. Seasonal cycles of VNT and CPR abundance were similar for near-surface residents. VNT: CPR abundance ratios varied year-round for vertical migrants, as ontogenetic migrants shifted their vertical distribution, and as diel migrants changed their migratory behaviour. For some taxa, differences in annual average VNT: CPR abundance ratios between regions suggest differences in vertical distribution, while for others differences in inter-annual variability for VNT and CPR abundances suggest differences in the dynamics of the near- and sub-surface components of the populations. [ABSTRACT FROM AUTHOR]

We characterize long‐term trends of sea surface temperature (SST), absolute dynamic topography, and chlorophyll‐a (CHL) in the Patagonian shelf break front (SBF) using 27 years (1993–2019) of satellite data. Warming of the Argentinean shelf waters and the southwestward displacement of the Brazil‐Malvinas Confluence (BMC) impact the northernmost extension of the SBF. Cooling of the Malvinas Current (MC) and the concurrent warming of the adjacent shelf waters lead to a significant increase of SST gradients along the outer shelf. The southwestward displacement of the BMC implies a similar shift of the SBF. An increase in CHL trend appears to be associated with southerly wind anomalies along the shelf break. We estimate a southward shift of the northernmost penetration of the MC of −0.11 ± 0.076°/decade. Plain Language Summary: Climate change is drastically affecting global fisheries, impacting marine resources, economic revenues and the livelihood of local communities. This manuscript describes the impact of climate change on one of the largest chlorophyll‐a hotspots of the world ocean: The frontal system of the Patagonian shelf break, which is located in the southwestern portion of the South Atlantic Ocean. The urgency to study this highly productive but scarcely sampled region is predicated upon the necessity to bring it to the attention of scientific and political stakeholders, who are largely unaware of the climate related changes of the regional oceanic conditions and their impact on the marine ecosystems. We report that as a consequence of climate change there has been a warming of the Argentine shelf waters, a southwestward displacement of the Shelf Break Front, a change of speed of major currents, and a positive trend of chlorophyll‐a concentration associated with southerly wind anomalies along the shelf break. The rate of southward shift of the Shelf Break Front is −0.11 ± 0.076° decade. Key Points: Warming of continental shelf waters strengthens the cross‐shelf break temperature gradientsObservations indicate a long‐term southward and westward displacements of the Brazil Current and Brazil‐Malvinas ConfluenceWe present a new methodology to determine the northernmost latitude of the Malvinas Current [ABSTRACT FROM AUTHOR]

The provision of reliable results from numerical wave models implemented over vast ocean areas can be considered as a time-consuming process. In this regard, the estimation of areas with maximum similarity in wave climate spatial areas and the determination of associated representative point locations for these areas can play an important role in climate research and in engineering applications. To deal with this issue, we apply a state-of-the-art clustering method, Geo-SOM, to determine geographical areas with similar wave regimes, in terms of mean wave direction (MWD), mean wave period (T0), and significant wave height (Hs). Although this method has many strengths, a weakness is related to detection and accounting of the most extreme and rare events. To resolve this deficiency, an initial preprocessing method (called PG-Geo-SOM) is applied. To evaluate the performance of this method, extreme wave parameters, including Hs and T0, are calculated. We simulate the present climate, represented as 1979 to 2017, compared to the future climate, 2060–98, following the Intergovernmental Panel on Climate Change (IPCC) future scenario RCP8.5 in the northwestern Atlantic Ocean. In this approach, the wave parameter data are divided into distinct groups, or clusters, motivated by their geographical positions. For each cluster, the centroid spatial point and the time series of data are extracted, for Hs, MWD, and T0. Extreme values are estimated for 5-, 10-, 25-, 50-, and 100-yr return periods, using Gumbel, exponential, and Weibull stochastic models, for both present and future climates. Results show that for parameter T0, the impact of climate change for the study area is a decreasing trend, while for Hs, in coastal and shelf areas up to about 1000 km from the coastline, increasing trends are estimated, and in open-ocean areas, far from the coast, decreasing trends are obtained. [ABSTRACT FROM AUTHOR]

Abstract: The wide, sediment-starved continental shelf and modern coastal areas of the southeastern United States retain well-preserved but scattered remnants of a submerged paleolandscape. This paper presents a conceptual model of stratigraphic deposition and landscape formation since the last interglacial on the continental shelf of South Carolina, with portions of North Carolina, Georgia, and Florida (USA). Data for this study include multibeam bathymetry surveys, sidescan sonar mosaics, high-resolution subbottom profiles, and ground-truth surveys from −250m to the modern tidewater region. Four bathymetric zones are recognized with eleven landforms and landform indicators. The described zones range in depths from the modern shoreline, across the shelf, and over the shelf edge to −250m MSL. Relative sea level curves are presented for the area and discussed in conjunction with cultural and climatic events. The potential for preservation of Paleoamerican sites is high at the shelf edge between −130m and −45m, with Archaic and later occupations likely in depths of less than −25m. Prominent vantage points for Paleoamericans (>11kya) would have existed at the shelf edge, and tidewater resources would have been available nearby for a period of almost 6ka. Rapid transgression rates (>60km/ka) after the sea level rose over the shelf edge make preservation of tidewater sites less likely on the outer and middle shelf. Searches for the earliest Paleoamericans should focus on promontories at the edge of the shelf and along future discoveries of paleoincisions on the shelf. Mapping and delineating this paleolandscape and associated unconsolidated sedimentary deposits interspersed with rocky plains and ledges will continue to be a priority to marine archeologists, coastal managers, fishery scientists, and marine spatial planners over the next several decades. [Copyright &y& Elsevier]

Landfast sea ice (fast ice) is an important though poorly understood component of the cryosphere on the Antarctic continental shelf, where it plays a key role in atmosphere–ocean–ice-sheet interaction and coupled ecological and biogeochemical processes. Here, we present a first in-depth baseline analysis of variability and change in circum-Antarctic fast-ice distribution (including its relationship to bathymetry), based on a new high-resolution satellite-derived time series for the period 2000 to 2018. This reveals (a) an overall trend of -882±824 km 2 yr -1 (-0.19±0.18 % yr -1) and (b) eight distinct regions in terms of fast-ice coverage and modes of formation. Of these, four exhibit positive trends over the 18-year period and four negative. Positive trends are seen in East Antarctica and in the Bellingshausen Sea, with this region claiming the largest positive trend of +1198±359 km 2 yr -1 (+1.10±0.35 % yr -1). The four negative trends predominantly occur in West Antarctica, with the largest negative trend of -1206±277 km 2 yr -1 (-1.78±0.41 % yr -1) occurring in the Victoria and Oates Land region in the western Ross Sea. All trends are significant. This new baseline analysis represents a significant advance in our knowledge of the current state of both the global cryosphere and the complex Antarctic coastal system, which are vulnerable to climate variability and change. It will also inform a wide range of other studies. [ABSTRACT FROM AUTHOR]

The first and second branches of the Tsushima Warm Current flow on the continental shelf and along the shelf break/slope in the southwestern Japan Sea, respectively. The second branch corresponds to the offshore side of the bottom temperature front between the offshore cold and nearshore warm waters. Across the Tsushima Warm Current on the continental shelf and the shelf edge, five bottom‐mounted ADCPs with temperature sensors were deployed between middle June and late July 2014. At the shelf edge, the bottom temperature varied with the diurnal tidal cycle. The offshore bottom cold‐water intruded into the continental shelf region in conjunction with the fortnightly spring‐neap (2‐week) cycle which is the modulation of the diurnal K1 and O1 internal tides. The bottom temperature front and the first branch of the Tsushima Warm Current on the continental shelf intensified in response to the bottom cold‐water intrusion. Plain Language Summary: The path of Tsushima Warm Current and its variation, in the southwestern Japan Sea after passing through the Tsushima Straits, are not well understood because of the mesoscale eddy activities and the strong tidal currents. In this study, using the observational time series data of the current profiles and the bottom temperatures, we found that the Tsushima Warm Current on the continental shelf intensified about every 2 weeks. The velocity enhancement was caused by the short‐term variation and its modulation of the diurnal internal tides. Key Points: Fortnightly variation of the Tsushima Warm Current on continental shelfVariation of the Tsushima Warm Current locally controlled by internal tidesRelation between the Tsushima Warm Current and the bottom temperature front [ABSTRACT FROM AUTHOR]

Abstract: In this paper, it was hypothesized that coastal upwelling increases in western boundary current influenced regions due to global warming. A state-space decomposition of the alongshore wind stress time-series exhibited an intensification during the “upwelling season” in the last 20 years (1988–2008), which agrees well with the above hypothesis. However, when applying the same decomposition to a temperature time-series at Qinglan station (located at the eastern Hainan coast) over the past 50 years (1960–2006), a negative trend was found. This indicates that the simple relation between alongshore wind stress and upwelling strength is not valid in the study area, but that other non-local factors might influence the inter-annual variability of the upwelling significantly. To identify these possible non-local effects, results of a model simulation were analyzed. From these model data an acceptable relationship between the non-locally driven western boundary current and the strength of the upwelling can be inferred. Furthermore, an “SST (sea surface temperature) upwelling index” was introduced, calculated by the simulated offshore–onshore temperature difference. This index exhibits a good correlation with the Qinglan “observational upwelling time-series”, demonstrating that the latter is a good indicator of the upwelling trend. Finally, it is shown that inter-annual oscillations of employed temperature records correlate well with the El Niño signal. [Copyright &y& Elsevier]

This paper reviews North Atlantic shelf seas palaeoclimate during the interval 4–3Ma, prior to and incorporating the ‘Mid-Pliocene warm period’ (ca 3.29–2.97Ma). Fossil assemblages and stable isotope data demonstrate northwards extension of subtropical faunas along the coast of the Carolinas–Virginia (Yorktown and Duplin Formations) relative to the present day, suggesting a more vigorous Florida Current, with reduced seasonality and warm water extending north of Cape Hatteras (reconstructed annual range for Virginia 12–30°C). This interpretation supports conceptual models of increased meridional heat transport for the Pliocene. Sea temperatures for Florida (Lower Pinecrest Beds) were similar to or slightly cooler than (summers 25–27°C) today, and were probably influenced by seasonal upwelling of cold deep water. Reduced seasonality is also apparent in the Coralline Crag Formation of the southern North Sea, with ostracods suggesting winter sea temperatures of 10°C (modern 4°C). However, estimates from Pliocene bivalves (3.6–16.6°C) are similar to or cooler than the present day. This ‘mixed’ signal is problematic given warmer seas in the Carolinas–Virginia, and climate model and oceanographic data that show warmer seas in the ‘Mid-Pliocene’ eastern North Atlantic. This may be because the Coralline Crag Formation was deposited prior to peak Mid-Pliocene warmth. [ABSTRACT FROM AUTHOR]

The Southern Ocean has been disproportionately affected by climate change and is therefore an ideal place to study the influence of changing environmental conditions on ecosystems. Changes in the demography of predator populations are indicators of broader shifts in food web structure, but long‐term data are required to study these effects. Southern elephant seals (Mirounga leonina) from Macquarie Island have consistently decreased in population size while all other major populations across the Southern Ocean have recently stabilized or are increasing. Two long‐term mark‐recapture studies (1956–1967 and 1993–2009) have monitored this population, which provides an opportunity to investigate demographic performance over a range of climatic conditions. Using a 9‐state matrix population model, we estimated climate influences on female survival by incorporating two major climatic indices into our model: The Southern Annular Mode (SAM) and the Southern Oscillation Index (SOI). Our best model included a 1 year lagged effect of SAM and an unlagged SOI as covariates. A positive relationship with SAM1 (lagged) related the previous year's SAM with juvenile survival, potentially due to changes in local prey availability surrounding Macquarie Island. The unlagged SOI had a negative effect on both juvenile and adult seals, indicating that sea ice dynamics and access to foraging grounds on the East Antarctic continental shelf could explain the different contributions of ENSO events on the survival of females in this population. [ABSTRACT FROM AUTHOR]

It has been reported that the sea surface temperature (SST) trend of the East China Sea during the twentieth century was a couple of times larger than the global mean SST trend. However, the detailed spatial structure of the SST trend in the East China Sea and its mechanism have not been understood. The present study examines the SST trend in the East China Sea from 1901 to 2010 using observational data and a Regional Ocean Modeling System (ROMS) with an eddy-resolving horizontal resolution. A comparison among two observational datasets and the model output reveals that enhanced SST warming occurred along the Kuroshio and along the coast of China over the continental shelf. In both regions, the SST trends were the largest in winter. The heat budget analysis using the model output indicates that the upper-layer temperature rises in both regions were induced by the trend of ocean advection, which was balanced in relation to the increase of surface net heat release. In addition, the rapid SST warming along the Kuroshio was induced by the acceleration of the Kuroshio. Sensitivity experiments revealed that this acceleration was likely caused by the negative wind stress curl anomalies over the North Pacific. In contrast, the enhanced SST warming along the China coast resulted from the ocean circulation change over the continental shelf by local atmospheric forcing. [ABSTRACT FROM AUTHOR]

Physical oceanography of New Zealand/Aotearoa shelf seas - a review. Keywords: Oceanography; shelf seas; climate change; open data; continental shelf EN Oceanography shelf seas climate change open data continental shelf 1 5 5 02/20/21 20210301 NES 210301 Aotearoa New Zealand is a marine nation. The motivation for this special issue on New Zealand's Shelf Seas emerged from the 2017 Physical Oceanography Workshop held in Wellington organised by Dr. Natalie Robinson of NIWA. At the meeting it was clear that there was a critical mass of mature regionally-specific research to form the basis of a special issue on physical oceanography of New Zealand's shelf seas. [Extracted from the article]

Under climate change, the Bering–Chukchi continental shelves have experienced drastic sea ice loss, breaking the minimum sea ice extent record in 2018. In this paper, we report a distinctive spring phytoplankton bloom in the Bering Strait based on year-round mooring observations during 2016–2018. A near-bottom fluorescence sensor mounted on a mooring and satellite observations indicate that, despite the early sea ice retreat in spring of 2018 (mid-April), the spring phytoplankton bloom was not observed for more than 20 days after sea ice retreat. In contrast, in 2017 when sea ice retreat did not occur as early as it did in 2018 (early May), the bloom and sea ice retreat occurred in tighter synchrony. Mooring (2016–2018) and satellite observations (2003–2011, 2013–2018) suggest that an open-water bloom rather than an ice-edge bloom occurred in the Bering Strait in the spring of 2018. Early sea ice retreat apparently provided unfavorable conditions for an ice-edge bloom due to weak sunlight and winter-like weather. Mid-winter sea ice loss was promoted by unusual southerly winds, bringing in warm water from the south. For the Bering Strait, the end of April is a reference date for sea ice retreat that distinguishes between an open-water bloom and an ice-edge bloom, which is approximately one month later than that in the southeastern Bering Sea. [ABSTRACT FROM AUTHOR]

Conodonts, one of the longest-lived early groups of vertebrates, have a very complete fossil record ranging from the late Cambrian to the end of the Triassic and persisted through many global climatic and biotic events. In this paper, we analyse a large dataset harvested from the Paleobiology Database to compute global diversity curves at the generic level and explore patterns of conodont paleogeographic distribution. Our results partly confirm the most prominent findings of earlier studies including the occurrence of an Ordovician acme, a Permian nadir and a short-lived Triassic recovery. Major peaks of origination were found in the Early Ordovician and Early Triassic, while major extinctions occurred in the Upper Ordovician and Pennsylvanian. Paleogeographical extent of conodonts was impacted by i) the position of paleo-continents (notably impacting the latitudinal gradient of diversity), ii) the available continental shelf area and iii) ice sheets expansion. Diversity trends were mostly impacted by transitions between hothouse and icehouse ages, with major glaciations and associated marine regressions co-occurring with major extinctions. The influence of global sea level was less marked than that of temperature. However, the final demise of conodonts at the end of the Triassic did not coincide with either a major glaciation or marine regression. This supports the view that extinction of the group was mostly due to biotic factors such as competition with 'Mesozoic' taxa. • Conodont biodiversity was significantly impacted by sea-level and sea temperature; • Hit by end-Ordovician and end-Carboniferous extinction peaks; • Major extinctions were related to glaciation and sea-level drop; • Abiotic context of final extinction was different, suggesting biotic effects. [ABSTRACT FROM AUTHOR]

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Projecting the future effects of climate change on marine fished populations can help prepare the fishing industry and management systems for resulting ecological, social and economic changes. Generating projections using multiple climate scenarios can provide valuable insights for fisheries stakeholders regarding uncertainty arising from future climate data.Using a range of climate projections based on the Intergovernmental Panel on Climate Change A1B, RCP4.5 and RCP8.5 climate scenarios, we modelled abundance of eight commercially important bottom dwelling fish species across the Celtic Sea, English Channel and southern North Sea through the 21st century. This region spans a faunal boundary between cooler northern waters and warmer southern waters, where mean sea surface temperatures are projected to rise by 2 to 4°C by 2098.For each species, Generalized Additive Models were trained on spatially explicit abundance data from six surveys between 2001 and 2010. Annual and seasonal temperatures were key drivers of species abundance patterns. Models were used to project species abundance for each decade through to 2090.Projections suggest important future changes in the availability and catchability of fish species, with projected increases in abundance of red mullet Mullus surmuletus L., Dover sole Solea solea L., John dory Zeus faber L. and lemon sole Microstomus kitt L. and decreases in abundance of Atlantic cod Gadus morhua L., anglerfish Lophius piscatorius L. and megrim Lepidorhombus whiffiagonis L. European plaice Pleuronectes platessa L. appeared less affected by projected temperature changes. Most projected abundance responses were comparable among climate projections, but uncertainty in the rate and magnitude of changes often increased substantially beyond 2040.Synthesis and applications. These results indicate potential risks as well as some opportunities for demersal fisheries under climate change. These changes will challenge current management systems, with implications for decisions on target fishing mortality rates, fishing effort and allowable catches. Increasingly flexible and adaptive approaches that reduce climate impacts on species while also supporting industry adaptation are required. [ABSTRACT FROM AUTHOR]

Iron (Fe) is a productivity-limiting nutrient in the ocean. However, the sources of dissolved Fe (dFe) in the deep ocean and how they respond to tectonic and climate changes are still poorly understood. In the northern hemisphere, dust flux to the low-latitude western Pacific has increased dramatically since the late Miocene associated with intense aridification of the Asian inland. Meanwhile, the terrigenous material supply to the open ocean might have also changed as a result of the reorganization of the Pacific circulation due to the gradual closure of seaways in the low latitudes. Therefore, the western Pacific is a characteristic region for understanding the sources of dFe in the deep ocean and their responses to long term climate changes. Here, we present data on isotopic evolution of dFe and dissolved Pb since ∼8 Ma based on ferromanganese crust METG-03 (16.0°N, 152.0°E, 3850 m water depth) in the western Pacific deep water. Our results show that δ56Fe of the crust remains fairly stable since the late Miocene, i.e., about −0.32±0.08‰ (2SD). We infer that δ56Fe of dFe in the deep western Pacific is relatively invariant at ∼0.45 ±0.1‰ based on the Fe isotopic fractionation between hydrogenetic crust and the seawater dissolved component. The reconstructed isotope signature is similar to the measured δ56Fe value (0.37±0.15‰) of the intermediate to deep waters in the modern low-latitude western Pacific region close to the island arcs, but is significantly higher than that of the eastern Pacific deep waters near South America which is controlled by the reductive dissolution of continental shelf sediments and the hydrothermal inputs (δ56Fe<−0.1‰). The deep-water 206Pb/204Pb ratio recorded by METG-03 displays systematic increase at about 8–4 Ma, reflecting increased input from sediment dissolution of low-latitude island arcs associated with reorganization of the western Pacific deep circulation. Notably, Fe isotopes of terrigenous materials from different sources are similar, while their dissolved Fe isotopic signatures released to the ocean are mainly controlled by the mechanism of particle dissolution. The stability of δ56Fe and systematic changes in Pb isotopes over the last ∼8 Ma thus suggest that Asian dust dissolution and hydrothermal inputs are likely only minor sources of dFe in the low-latitude deep western Pacific, while the acquisition and transport of dFe from shelf sediments by organic ligand binding in the oxic environment is the major dFe source which keeps stable on tectonic time scales since the late Miocene. [ABSTRACT FROM AUTHOR]

Divergent movement strategies have enabled wildlife populations to adapt to environmental change. In recent decades, the Southern Beaufort Sea subpopulation of polar bears (Ursus maritimus) has developed a divergent movement strategy in response to diminishing sea ice where the majority of the subpopulation (73–85%) stays on the sea ice in summer and the remaining bears move to land. Although declines in sea ice are generally considered a challenge to energy balance in polar bears residing in some regions of the Arctic, little quantitative data exists concerning the seasonal energy expenditures of this apex marine carnivore. We used GPS satellite collars with tri‐axial accelerometers and conductivity sensors to measure the location, behavior, and energy expenditure of five adult female polar bears in the southern Beaufort Sea across seasons of sea ice breakup and minimum extent. Using a Bayesian mixed‐effects model, we found that energy expenditure was influenced by month, ocean depth, and habitat type (sea ice or land). Total energy expenditure from May through September ranged from 37.7 to 47.2 mJ/kg for individual bears. Bears that moved to land expended 7% more energy on average from May through September than bears that remained on the receding sea ice. In August, when bears were moving from the sea ice to land or moving north with the receding pack ice, bears that moved to land spent 7% more time swimming and expended 22% more energy. This means the immediate cost of moving to land exceeded the cost of remaining on the receding summer pack ice. These findings suggest a physiological reason why the majority of the Southern Beaufort Sea subpopulation continues to inhabit a diminishing summer ice platform. However, bears that moved to land spent 29% more time in preferred hunting habitats over the continental shelf than bears that remained on the sea ice. Bears on land also had access to subsistence‐harvested bowhead whale carcasses. Hence, our findings indicate there may be a greater overall energetic benefit to move to land in this region, which suggests that the use of the diminishing summer sea ice may be functioning as an ecological trap. [ABSTRACT FROM AUTHOR]

The mid to late Pliocene (~4.2–2.8 Ma.) represents an experiment in climate sensitivity to orbital pacing in which nearly all continental ice was confined to the Southern Hemisphere. Most studies have emphasized the dominant role of obliquity in determining changes in ice volume and temperature at this time, although most records come from the Northern Hemisphere, instead of the hemisphere where the bulk of ice resided. We present the first orbitally‐resolved, mid to late Pliocene Southern Hemisphere paired records of surface and subsurface variability from two deep ocean archives from the Southwest Pacific Ocean (Sites 594 and 1125). These records indicate dominance of low frequencies centered at ~100 kyr for this time period. Because these signatures extend coherently and synchronously from middepth water properties (δ13C, δ18O of benthic foraminifera), which have their chemistry set in the subantarctic belt, to the surface (alkenone‐derived surface temperature estimates, color reflectance, and magnetic susceptibility), we infer that the fingerprint of the ~100‐kyr cycles must have extended over a large region of the Southern Hemisphere. We propose that nonlinearities in climate response to precessional forcing—most likely through ice sheet and/or carbon cycle behavior—generated the observed low frequency. A review of published mid to late Pliocene time series suggests that the ~100‐kyr pacing may be a widespread phenomenon and that major approximately 100‐kyr excursions in Pliocene climate were an important overlay to the underlying 41‐kyr glacial‐interglacial rhythm. These results caution against uncritical use of existing Pliocene isotopic templates to construct high‐resolution age models. Plain Language Summary: We recreated a detailed account of surface and subsurface ocean change at two locations within the Southern Hemisphere in the middle to late Pliocene Epoch (~4.2–2.8 Ma) using data obtained from deep‐ocean sediment cores. Our work showed that all variables measured (each representing a response from different parts of the climate system) fluctuated synchronously through time at specific rhythms and one of which, at approximately 100 kyr, was surprising to find. We found that the pervasive nature of this rhythm at ~100 kyr in our reconstructions is also found in other data sets connected to the Antarctic region. First, we propose that approximately 100‐kyr excursions in Pliocene climate are an important component in the overall pacing of glacial to interglacial times in the Pliocene. Such large excursions in climate would require powerful nonlinear feedbacks to forcing from the Earth's orbital precession cycle, likely involving ice sheet or carbon cycle dynamics. Second, we suggest that current global benthic isotope stacks (taken as an average representation of deep ocean temperature and ice volume changes on Earth) may not be fully representative of climate variability in some intervals of the Pliocene and therefore must be used carefully if used as a means to convert depth to time. Key Points: New, high‐resolution, paired surface‐subsurface paleoclimate reconstructions from the Southern Hemisphere, mid to late Pliocene EpochDominance of low frequencies centered at 100 kyr, extending coherently and synchronously from middepth water properties to the surfaceLow‐frequency dominance in power spectra likely related to underlying sensitivity to precessional forcing, requiring nonlinear amplifiers [ABSTRACT FROM AUTHOR]

Stratigraphic pollen analysis of terrestrial peat–mud layers from a buried bald cypress (Taxodium distichum) forest allows study of autochthonous fossil pollen profiles from a glacial refugium along the northern Gulf of Mexico coast in the context of fluctuating sea levels. The site is in 18 m of water, offshore from Orange Beach, Alabama, USA. Exposed cypress stumps are in growth position, still rooted in sediment. Radiocarbon dating of peat and optically stimulated luminescence dating of subjacent sediments yielded an age range of 72–45 ka. We hypothesize the site was rapidly buried by floodplain aggradation from pulsed sea‐level rise during the glacial interval. Pollen results from the lowermost peat layer are consistent with a bald cypress − tupelo gum (Nyssa aquatica) backwater forest. This was followed by a brief transitional period where the pollen assemblage is similar to Atlantic Coastal Plain Blackwater Levee/Bar Forests, but may be evidence of a no‐modern analog community. Final Pleistocene pollen spectra indicate a more open environment, dominated by grasses (Poaceae) and sedges (Cyperaceae). [ABSTRACT FROM AUTHOR]

Basal melting of Antarctic ice shelves is expected to increase during the twenty-first century as the ocean warms, which will have consequences for ice sheet stability and global sea level rise. Here we present future projections of Antarctic ice shelf melting using the Finite Element Sea Ice/Ice-Shelf Ocean Model (FESOM) forced with atmospheric output from models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). CMIP5 models are chosen based on their agreement with historical atmospheric reanalyses over the Southern Ocean; the best-performing models are ACCESS 1.0 and the CMIP5 multimodel mean. Their output is bias-corrected for the representative concentration pathway (RCP) 4.5 and 8.5 scenarios. During the twenty-first-century simulations, total ice shelf basal mass loss increases by between 41% and 129%. Every sector of Antarctica shows increased basal melting in every scenario, with the largest increases occurring in the Amundsen Sea. The main mechanism driving this melting is an increase in warm Circumpolar Deep Water on the Antarctic continental shelf. A reduction in wintertime sea ice formation simulated during the twenty-first century stratifies the water column, allowing a warm bottom layer to develop and intrude into ice shelf cavities. This effect may be overestimated in the Amundsen Sea because of a cold bias in the present-day simulation. Other consequences of weakened sea ice formation include freshening of High Salinity Shelf Water and warming of Antarctic Bottom Water. Furthermore, freshening around the Antarctic coast in our simulations causes the Antarctic Circumpolar Current to weaken and the Antarctic Coastal Current to strengthen. [ABSTRACT FROM AUTHOR]

Knowledge of regional wave climates is critical for coastal planning, management, and protection. In order to develop a regional wave climate, it is important to understand the atmospheric systems responsible for wave generation. This study examines the variability of the southwest Western Australian (SWWA) shelf and nearshore wind wave climate and its relationship to southern hemisphere climate variability represented by various atmospheric indices: the southern oscillation index (SOI), the Southern Annular Mode (SAM), the Indian Ocean Dipole Mode Index (DMI), the Indian Ocean Subtropical Dipole (IOSD), the latitudinal position of the subtropical high-pressure ridge (STRP), and the corresponding intensity of the subtropical ridge (STRI). A 21-year wave hindcast (1994-2014) of the SWWA continental shelf was created using the third generation wave model Simulating WAves Nearshore (SWAN), to analyse the seasonal and inter-annual wave climate variability and its relationship to the atmospheric regime. Strong relationships between wave heights and the STRP and the STRI, a moderate correlation between the wave climate and the SAM, and no significant correlation between SOI, DMI, and IOSD and the wave climate were found. Strong spatial, seasonal, and inter-annual variability, as well as seasonal longer-term trends in the mean wave climate were studied and linked to the latitudinal changes in the subtropical high-pressure ridge and the Southern Ocean storm belt. As the Southern Ocean storm belt and the subtropical high-pressure ridge shifted southward (northward) wave heights on the SWWA shelf region decreased (increased). The wave height anomalies appear to be driven by the same atmospheric conditions that influence rainfall variability in SWWA. [ABSTRACT FROM AUTHOR]

Abstract: Refugia are areas relatively buffered from contemporary climate change that enable the persistence of valued physical, ecological, or sociocultural resources. Spatially identifying refugia is important for conservation and applied management. Yet the concept of refugia has not been broadly extended to marine ecosystems. Here, we analyze data from a unique and long‐term (1999–2015) standardized survey of pelagic marine and anadromous species off Oregon and Washington in the northern California Current to identify such refugia. We use quantitative approaches to assess locations with high species richness and community persistence relative to local and basin‐scale environmental fluctuations. We have identified a potential climate change refugial zone along the continental shelf of Washington State in the Northeastern Pacific Ocean, characterized by a species‐rich community with low interannual temporal community change. This region contrasts with adjacent areas to the south and offshore that have lower species richness, and higher temporal species community change. Also, using spatially variant generalized additive mixed models, we identify areas with species compositions that are more influenced by basin‐scale climatic fluctuations than others. We propose that upwelling regions with retentive topographic features, such as wide continental shelves, can function as marine refugia for pelagic fauna, whereas offshore locations are potentially more climatically sensitive and experience high temporal change in species composition. Further identification of these marine refugia using in situ data for pelagic biodiversity and climatically sensitive areas can help guide management in the face of inevitable climatically driven change. [ABSTRACT FROM AUTHOR]

Mesoscale eddies drive variability in phytoplankton functional trait composition and primary productivity (PP) relative to adjacent waters. Offshore waters in southeast Australia are subject to substantial mesoscale eddies that form when the East Australian Current (EAC) travels poleward along the coast, forming distinctive habitats in the upper ocean. Eddies provide an important enrichment mechanism in the nitrogen-limited waters of the Tasman Sea, yet there is limited knowledge of PP within cold- and warm-core eddies in the region and how physico-chemical and biological factors affect phytoplankton communities in this variable environment. We addressed the scarcity of observations by quantifying net PP using 13C isotopic enrichment incubations of surface waters over 10 degrees of latitude, comparing phytoplankton species composition in five different environments: a coastal shelf station, an oceanic cold and warm-core eddy, and a coastal dipole. Cold-core (cyclonic) eddies were significantly more productive than their warm-core (anticyclonic) counterparts (∼35 versus 0 mg C m−3 d−1), with centric diatoms the most prominent phytoplankton group, with a relatively high centric:pennate ratio. The diffuse attenuation coefficient, K d (PAR), and silicate were the best overall predictors of phytoplankton composition, explaining 88% of variation based on pigment analysis and size fractionation. Variance in net PP did not correlate significantly with physico-chemical parameters frequently used in PP models (temperature, K d [PAR], Chl a), yet inclusion of size-fractionated Chl a generated substantial improvement in our statistical model (from 36 to 77%). We show that cold-core eddies play a key role in regulating PP in eastern Australian waters and highlight a need for eddy-resolving models to incorporate descriptors of phytoplankton size structure to improve the accuracy of PP forecasts in eddy intensive regions. • Mesoscale eddies modulate primary productivity dynamics along the East Australian coast. • Knowledge of phytoplankton size structure improves prediction of primary productivity. • Phytoplankton community structure can be predicted from light and silicate levels. • Centric diatoms are the most prominent phytoplankton group in East Australian cyclonic eddies. [ABSTRACT FROM AUTHOR]

Records of past warm periods are essential for understanding interglacial climate system dynamics. Marine Isotope Stage 11 occurred from 425 to 394 ka, when global ice volume was the lowest, sea level was the highest, and terrestrial temperatures were the warmest of the last 500 kyr. Because of its extreme character, this interval has been considered an analog for the next century of climate change. The Bering Sea is ideally situated to record how opening or closing of the Pacific-Arctic Ocean gateway (Bering Strait) impacted primary productivity, sea ice, and sediment transport in the past; however, little is known about this region prior to 125 ka. IODP Expedition 323 to the Bering Sea offered the unparalleled opportunity to look in detail at time periods older than had been previously retrieved using gravity and piston cores. Here we present a multi-proxy record for Marine Isotope Stages 12 to 10 from Site U1345, located near the continental shelf-slope break. MIS 11 is bracketed by highly productive laminated intervals that may have been triggered by flooding of the Beringian shelf. Although sea ice is reduced during the early MIS 11 laminations, it remains present at the site throughout both glacials and MIS 11. High summer insolation is associated with higher productivity but colder sea surface temperatures, which implies that productivity was likely driven by increased upwelling. Multiple examples of Pacific-Atlantic teleconnections are presented including laminations deposited at the end of MIS 11 in synchrony with millennial-scale expansions in sea ice in the Bering Sea and stadial events seen in the North Atlantic. When global eustatic sea level was at its peak, a series of anomalous conditions are seen at U1345. We examine whether this is evidence for a reversal of Bering Strait throughflow, an advance of Beringian tidewater glaciers, or a turbidite. [ABSTRACT FROM AUTHOR]

Sponge communities on the Antarctic continental shelf currently represent one of the most extensive sponge grounds in the world, and all sponge classes are known to occur in the Southern Ocean. Main objectives of this study conducted at the tip of the Antarctic Peninsula were (1) to identify all sampled sponges and (2) to investigate whether the species composition and species richness of Southern Ocean sponge communities in the area of the Antarctic Peninsula are significantly influenced by environmental variables. The studied material originated from 25 AGT catches and was sampled during the expedition ANT-XXIX/3 of RV Polarstern. Samples were collected in three large-scale areas in the vicinity of the Antarctic Peninsula: Bransfield Strait, Drake Passage and Weddell Sea. The following six environmental variables were measured from bottom water samples (except for sea-ice cover): depth (m), light transmission (%), oxygen (µmol/kg), salinity, sea-ice cover (%) and temperature (°C). Two hundred and sixty-three sponge samples were analyzed, and 81 species of 33 genera from all Porifera classes (Calcarea, Demospongiae, Hexactinellida and Homoscleromorpha) were identified. Total numbers of sponge species per sample station ranged from 1 to 29. A detrended correspondence analysis and a backward-stepwise model selection were performed to check whether species composition and richness were significantly influenced by environmental variables. The analyses revealed that none of the measured environmental variables significantly influenced species composition but that species richness was significantly influenced by (1) temperature and (2) the combination of temperature and depth. Results of this study are of crucial importance for development, performance and assessment of future protection strategies in case of ongoing climatic changes at the Antarctic Peninsula. [ABSTRACT FROM AUTHOR]

The Peruvian coastal upwelling is one of the most productive systems in the global ocean, with important impacts on the carbon cycle. Primary productivity there displays strong variations at the interannual to decadal timescales. However, down-core investigations rarely reach sufficient temporal resolution to assess the response of productivity to climatic variations at these timescales beyond the instrumental and historical periods. We here analyzed diatom assemblages, sea-surface temperatures (SSTs), and nitrogen and organic carbon contents on a laminated sediment core from the Peruvian continental shelf to trace variations in regional productivity over the last 3000 years. Our record provides evidence for different climatic and oceanic conditions with more humid and less productive conditions older than 2500 cal. yr BP and drier and more productive conditions younger than 2500 cal. yr BP. The last 2500 years also present much stronger centennial-scale variability with the occurrence of six intervals with higher total diatom abundances and stronger percentages in upwelling-related diatom species, representative of intensified productivity, congruent to lower percentages in benthic diatoms, indicative of reduced rainfall. These six periods were synchronous to intervals of enhanced Walker circulation, suggesting a strong imprint of the Pacific zonal circulation on productivity variations off Peru. Our record also demonstrates that SSTs did not vary in phase with productivity, arguing against the idea of regional SSTs controlled by the upwelling intensity, but were rather in agreement to SST records off southern Chile, suggesting that Peruvian SST variations were largely controlled by oceanic currents at southern high latitudes. [ABSTRACT FROM AUTHOR]

Deltas and estuaries built by the Mississippi/Atchafalaya River (MAR) in the United States and the Usumacinta/Grijalva River (UGR) in Mexico account for 80 percent of all Gulf of Mexico (GoM) coastal wetlands outside of Cuba. They rank first and second in freshwater discharge to the GoM and owe their natural resilience to a modular geomorphology that spreads risk across the coast-scape while providing ecosystem connectivity through shelf plumes that connect estuaries. Both river systems generate large plumes that strongly influence fisheries production over large areas of the northern and southern GoM continental shelves. Recent watershed process simulations (DLEM, MAPSS) driven by CMIP3 General Circulation Model (GCM) output indicate that the two systems face diverging futures, with the mean annual discharge of the MAR predicted to increase 11 to 63 percent, and that of the UGR to decline as much as 80 percent in the 21st century. MAR delta subsidence rates are the highest in North America, making it particularly susceptible to channel training interventions that have curtailed a natural propensity to shift course and deliver sediment to new areas, or to refurbish zones of high wetland loss. Undoing these restrictions in a controlled way has become the focus of a multi-billion-dollar effort to restore the MAR delta internally, while releasing fine-grained sediments trapped behind dams in the Great Plains has become an external goal. The UGR is, from an internal vulnerability standpoint, most threatened by land use changes that interfere with a deltaic architecture that is naturally resilient to sea level rise. This recognition has led to successful efforts in Mexico to protect still intact coastal systems against further anthropogenic impacts, as evidenced by establishment of the Centla Wetland Biosphere Preserve and the Terminos Lagoon Protected Area. The greatest threat to the UGR system, however, is an external one that will be imposed by the severe drying predicted for the entire Mesoamerican "climate change hot-spot", a change that will necessitate much greater international involvement to protect threatened communities and lifeways as well as rare habitats and species. [ABSTRACT FROM AUTHOR]

Climate change and decadal variability are impacting marine fish and invertebrate species worldwide and these impacts will continue for the foreseeable future. Quantitative approaches have been developed to examine climate impacts on productivity, abundance, and distribution of various marine fish and invertebrate species. However, it is difficult to apply these approaches to large numbers of species owing to the lack of mechanistic understanding sufficient for quantitative analyses, as well as the lack of scientific infrastructure to support these more detailed studies. Vulnerability assessments provide a framework for evaluating climate impacts over a broad range of species with existing information. These methods combine the exposure of a species to a stressor (climate change and decadal variability) and the sensitivity of species to the stressor. These two components are then combined to estimate an overall vulnerability. Quantitative data are used when available, but qualitative information and expert opinion are used when quantitative data is lacking. Here we conduct a climate vulnerability assessment on 82 fish and invertebrate species in the Northeast U.S. Shelf including exploited, forage, and protected species. We define climate vulnerability as the extent to which abundance or productivity of a species in the region could be impacted by climate change and decadal variability. We find that the overall climate vulnerability is high to very high for approximately half the species assessed; diadromous and benthic invertebrate species exhibit the greatest vulnerability. In addition, the majority of species included in the assessment have a high potential for a change in distribution in response to projected changes in climate. Negative effects of climate change are expected for approximately half of the species assessed, but some species are expected to be positively affected (e.g., increase in productivity or move into the region). These results will inform research and management activities related to understanding and adapting marine fisheries management and conservation to climate change and decadal variability. [ABSTRACT FROM AUTHOR]