Regional and global significance of Pliocene sea surface temperatures from the Gulf of Cadiz (Site U1387) and the Mediterranean

This paper characterizes non-indigenous fish species (NIS) and analyses both atmospheric and sea surface temperatures for the Mediterranean coast of Egypt from 1991 to 2020, in relation to previous reports in the same areas. Taxonomical characterization depicts 47 NIS from the Suez Canal (Lessepsian/alien) and 5 from the Atlantic provenance. GenBank accession number of the NIS mitochondrial gene, cytochrome oxidase 1, reproductive and commercial biodata, and a schematic Inkscape drawing for the most harmful Lessepsian species were reported. For sea surface temperatures (SST), an increase of 1.2 °C to 1.6 °C was observed using GIS software. The lack of linear correlation between annual air temperature and annual SST at the same detection points (Pearson r) could suggest a difference in submarine currents, whereas the Pettitt homogeneity test highlights a temperature breakpoint in 2005–2006 that may have favoured the settlement of non-indigenous fauna in the coastal sites of Damiette, El Arish, El Hammam, Alexandria, El Alamain, and Mersa Matruh, while there seems to be a breakpoint present in 2001 for El Sallum. This assessment of climate trends is in good agreement with the previous sightings of non-native fish species. New insights into the assessment of Egyptian coastal climate change are discussed.

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Absolute seasonal temperature estimates from clumped isotopes in bivalve shells suggest warm and variable greenhouse climate

Communications Earth & Environment ◽

10.1038/s43247-021-00193-9 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Niels J. de Winter ◽

Inigo A. Müller ◽

Ilja J. Kocken ◽

Nicolas Thibault ◽

Clemens V. Ullmann ◽

...

Keyword(s):

Seasonal Variability ◽

Sea Water ◽

Isotope Composition ◽

Sea Surface ◽

Mean Annual Temperature ◽

Seasonal Temperature ◽

Sea Surface Temperatures ◽

Surface Temperatures ◽

Temperature Reconstructions ◽

Bivalve Shells

AbstractSeasonal variability in sea surface temperatures plays a fundamental role in climate dynamics and species distribution. Seasonal bias can also severely compromise the accuracy of mean annual temperature reconstructions. It is therefore essential to better understand seasonal variability in climates of the past. Many reconstructions of climate in deep time neglect this issue and rely on controversial assumptions, such as estimates of sea water oxygen isotope composition. Here we present absolute seasonal temperature reconstructions based on clumped isotope measurements in bivalve shells which, critically, do not rely on these assumptions. We reconstruct highly precise monthly sea surface temperatures at around 50 °N latitude from individual oyster and rudist shells of the Campanian greenhouse period about 78 million years ago, when the seasonal range at 50 °N comprised 15 to 27 °C. In agreement with fully coupled climate model simulations, we find that greenhouse climates outside the tropics were warmer and more seasonal than previously thought. We conclude that seasonal bias and assumptions about seawater composition can distort temperature reconstructions and our understanding of past greenhouse climates.

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A spatiotemporal reconstruction of sea-surface temperatures in the North Atlantic during Dansgaard–Oeschger events 5–8

Climate of the Past ◽

10.5194/cp-14-901-2018 ◽

2018 ◽

Vol 14 (6) ◽

pp. 901-922 ◽

Cited By ~ 6

Author(s):

Mari F. Jensen ◽

Aleksi Nummelin ◽

Søren B. Nielsen ◽

Henrik Sadatzki ◽

Evangeline Sessford ◽

...

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

North Atlantic ◽

General Circulation ◽

Sea Surface ◽

Reconstruction Method ◽

Sea Surface Temperatures ◽

Proxy Data ◽

Surface Temperatures ◽

Temperature Reconstructions

Abstract. Here, we establish a spatiotemporal evolution of the sea-surface temperatures in the North Atlantic over Dansgaard–Oeschger (DO) events 5–8 (approximately 30–40 kyr) using the proxy surrogate reconstruction method. Proxy data suggest a large variability in North Atlantic sea-surface temperatures during the DO events of the last glacial period. However, proxy data availability is limited and cannot provide a full spatial picture of the oceanic changes. Therefore, we combine fully coupled, general circulation model simulations with planktic foraminifera based sea-surface temperature reconstructions to obtain a broader spatial picture of the ocean state during DO events 5–8. The resulting spatial sea-surface temperature patterns agree over a number of different general circulation models and simulations. We find that sea-surface temperature variability over the DO events is characterized by colder conditions in the subpolar North Atlantic during stadials than during interstadials, and the variability is linked to changes in the Atlantic Meridional Overturning circulation and in the sea-ice cover. Forced simulations are needed to capture the strength of the temperature variability and to reconstruct the variability in other climatic records not directly linked to the sea-surface temperature reconstructions. This is the first time the proxy surrogate reconstruction method has been applied to oceanic variability during MIS3. Our results remain robust, even when age uncertainties of proxy data, the number of available temperature reconstructions, and different climate models are considered. However, we also highlight shortcomings of the methodology that should be addressed in future implementations.

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Latest Miocene restriction of the Mediterranean Outflow Water: a perspective from the Gulf of Cádiz

Geo-Marine Letters ◽

10.1007/s00367-021-00693-9 ◽

2021 ◽

Vol 41 (2) ◽

Author(s):

Zhi Lin Ng ◽

F. Javier Hernández-Molina ◽

Débora Duarte ◽

Francisco J. Sierro ◽

Santiago Ledesma ◽

...

Keyword(s):

Mass Exchange ◽

Water Mass ◽

Atlantic Water ◽

Meridional Overturning Circulation ◽

Gulf Of Cadiz ◽

Mediterranean Outflow Water ◽

Gulf Of Cádiz ◽

Mediterranean Outflow ◽

The Mediterranean ◽

Water Mass Exchange

AbstractThe Mediterranean-Atlantic water mass exchange provides the ideal setting for deciphering the role of gateway evolution in ocean circulation. However, the dynamics of Mediterranean Outflow Water (MOW) during the closure of the Late Miocene Mediterranean-Atlantic gateways are poorly understood. Here, we define the sedimentary evolution of Neogene basins from the Gulf of Cádiz to the West Iberian margin to investigate MOW circulation during the latest Miocene. Seismic interpretation highlights a middle to upper Messinian seismic unit of transparent facies, whose base predates the onset of the Messinian salinity crisis (MSC). Its facies and distribution imply a predominantly hemipelagic environment along the Atlantic margins, suggesting an absence or intermittence of MOW preceding evaporite precipitation in the Mediterranean, simultaneous to progressive gateway restriction. The removal of MOW from the Mediterranean-Atlantic water mass exchange reorganized the Atlantic water masses and is correlated to a severe weakening of the Atlantic Meridional Overturning Circulation (AMOC) and a period of further cooling in the North Atlantic during the latest Miocene.

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