scholarly journals Robust comparison of climate models with observations using blended land air and ocean sea surface temperatures

2015 ◽  
Vol 42 (15) ◽  
pp. 6526-6534 ◽  
Author(s):  
Kevin Cowtan ◽  
Zeke Hausfather ◽  
Ed Hawkins ◽  
Peter Jacobs ◽  
Michael E. Mann ◽  
...  
Keyword(s):  
Climate Models ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Surface Temperatures

Clumped isotope evidence for polar warmth and reduced salinity during the Early Jurassic

2021 ◽  
Author(s):  
Thomas Letulle ◽  
Guillaume Suan ◽  
Mikhail Rogov ◽  
Mathieu Daëron ◽  
Arnauld Vinçon-Laugier ◽  
...  
Keyword(s):  
Climate Sensitivity ◽  
Climate Models ◽  
Early Jurassic ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Arctic Seas ◽  
Proxy Data ◽  
Western Tethys ◽  
Surface Temperatures ◽  
Clumped Isotope

<p><span>Greenhouse climates are periods characterized by high atmospheric CO<sub>2</sub> levels and the absence of large continental icecaps, conditions that define most of the Phanerozoic eon. Fossil record and proxy data from the Cretaceous-Early Paleogene (145-33 My) greenhouse interval suggest increased polar warmth and reduced latitudinal gradient. Such features are challenging for most climate models. They imply either misinterpretation of paleoenvironmental data or an underestimation of climate sensitivity under greenhouse climate. Here we present a new record from polar (>80°) paleolatitudes of the Early Jurassic (~180My) global warming episode known as the Toarcian Oceanic Anoxic Event. Carbonate clumped isotope (Δ47) thermometry and stable isotope analyses (</span><span>δ<sup>18</sup>O<sub>c, </sub>δ<sup>13</sup>C</span><span>) were performed on pristine aragonite bivalve shells from the Polovinnaya River succession (N Siberia) recording exceptionally low burial. Reconstructed growing season temperatures of 9.7</span><span>±5.2 to 19.0±3.4 °C and water δ<sup>18</sup>O<sub>w</sub> values of −4.6±1.2 to −2.2±0.8‰VSMOW imply increased warmth and significant freshwater contribution in the Toarcian Arctic seas, in line with coeval Siberian paleobotanical data. The unusually low δ<sup>18</sup>O<sub>w </sub>values confirm the incorrectness of assuming a spatially uniform δ<sup>18</sup>O<sub>sw</sub> value for calculation of δ<sup>18</sup>O-derived paleotemperatures. The inferred Early Jurassic polar sea surface temperatures are in good agreement with independent high latitude proxy data from Cretaceous and Eocene warming events. Together with coeval sea surface temperatures data from the western Tethys Ocean, our new data suggest a strong reduction of latitudinal temperature gradients during the Toarcian relative to modern gradients. The reconstructed polar warmth and reduction in latitudinal temperature gradient are substantially higher than those simulated by most climate models of the Jurassic to Eocene greenhouse periods, and support the increasing amount of data and models indicating an increase of climate sensitivity with CO<sub>2</sub> levels. Our results bring critical new constraints for model simulations of Jurassic temperatures and δ<sup>18</sup>O<sub>sw</sub> values and suggest that high climate sensitivity is the hallmark of greenhouse climates since at least 180 My.</span></p>

scholarly journals Reconstruction of sea-surface temperatures in the Canary Islands during Marine Isotope Stage 11

2019 ◽  
Vol 94 ◽  
pp. 195-209
Author(s):  
Thibault Clauzel ◽  
Chloé Maréchal ◽  
François Fourel ◽  
Abel Barral ◽  
Romain Amiot ◽  
...  
Keyword(s):  
Canary Islands ◽  
Climate Models ◽  
Marine Invertebrates ◽  
Isotopic Fractionation ◽  
Sea Surface ◽  
Marine Isotope Stage ◽  
Sea Surface Temperatures ◽  
Surface Temperatures ◽  
Carbon And Oxygen Isotope ◽  
Marine Deposit

AbstractThe study of paleoclimates enables us to improve and better constrain climate models in order to forecast future climate variations. Marine Isotope Stage 11 (MIS11), which began around 425,000 yr BP and lasted about 65,000 yr, is a warm isotope stage of paramount importance, because the astronomical configuration was similar to the one characterizing the Holocene. Therefore, this warm isotope stage is the most appropriate analog to present-day climate known to date. This study aims to provide new data on sea-surface temperatures (SSTs) inferred from the carbon and oxygen isotope compositions of skeletal carbonates of marine invertebrates preserved in two marine deposits of the Canary Islands located at Piedra Alta, Lanzarote, and Arucas, Gran Canaria. According to published isotopic fractionation equations the marine deposit from Arucas recorded SSTs of 15.9 ± 2.2°C on average, while the tsunamite from Piedra Alta recorded SSTs of 21.2 ± 1.9°C on average. Absolute dating, mollusc assemblages, and calculated marine temperatures suggest that the Arucas marine deposit corresponds to the beginning of MIS11, while the Piedra Alta tsunamite was formed during MIS11c. These results show that low latitudes also experienced sizable SST changes during interglacial stages.

scholarly journals Late Paleocene–early Eocene Arctic Ocean sea surface temperatures: reassessing biomarker paleothermometry at Lomonosov Ridge

2020 ◽  
Vol 16 (6) ◽  
pp. 2381-2400 ◽  
Author(s):  
Appy Sluijs ◽  
Joost Frieling ◽  
Gordon N. Inglis ◽  
Klaas G. J. Nierop ◽  
Francien Peterse ◽  
...  
Keyword(s):  
Climate Models ◽  
Sea Surface ◽  
Temperature Sensitive ◽  
Lomonosov Ridge ◽  
Early Eocene ◽  
Sea Surface Temperatures ◽  
Surface Temperatures ◽  
Late Paleocene ◽  
Air Temperatures ◽  
Thermal Maximum

Abstract. A series of papers published shortly after the Integrated Ocean Drilling Program Arctic Coring Expedition (ACEX, 2004) on Lomonosov Ridge indicated remarkably high early Eocene sea surface temperatures (SSTs; ca. 23 to 27 ∘C) and land air temperatures (ca. 17 to 25 ∘C) based on the distribution of isoprenoid and branched glycerol dialkyl glycerol tetraether (isoGDGT and brGDGT) lipids, respectively. Here, we revisit these results using recent analytical developments – which have led to improved temperature calibrations and the discovery of new temperature-sensitive glycerol monoalkyl glycerol tetraethers (GMGTs) – and currently available proxy constraints. The isoGDGT assemblages support temperature as the dominant variable controlling TEX86 values for most samples. However, contributions of isoGDGTs from land, which we characterize in detail, complicate TEX86 paleothermometry in the late Paleocene and part of the interval between the Paleocene–Eocene Thermal Maximum (PETM; ∼ 56 Ma) and the Eocene Thermal Maximum 2 (ETM2; ∼ 54 Ma). Background early Eocene SSTs generally exceeded 20 ∘C, with peak warmth during the PETM (∼ 26 ∘C) and ETM2 (∼ 27 ∘C). We find abundant branched GMGTs, likely dominantly marine in origin, and their distribution responds to environmental change. Further modern work is required to test to what extent temperature and other environmental factors determine their distribution. Published Arctic vegetation reconstructions indicate coldest-month mean continental air temperatures of 6–13 ∘C, which reinforces the question of whether TEX86-derived SSTs in the Paleogene Arctic are skewed towards the summer season. The exact meaning of TEX86 in the Paleogene Arctic thus remains a fundamental issue, and it is one that limits our assessment of the performance of fully coupled climate models under greenhouse conditions.

Sea-Surface Temperatures and the History of Monsoon Upwelling in the Northwest Arabian Sea during the Last 500,000 Years

1995 ◽  
Vol 43 (3) ◽  
pp. 355-361 ◽  
Author(s):  
Kay-Christian Emeis ◽  
David M. Anderson ◽  
Heidi Doose ◽  
Dick Kroon ◽  
Detlef Schulz-Bull
Keyword(s):  
Arabian Sea ◽  
Climate Models ◽  
Unsaturation Index ◽  
Sea Surface ◽  
Circulation System ◽  
Monsoon Circulation ◽  
Sea Surface Temperatures ◽  
Tropical Ocean ◽  
Surface Temperatures ◽  
Monsoon Winds

AbstractArabian Sea sediments record changes in the upwelling system off Arabia, which is driven by the monsoon circulation system over the NW Indian Ocean. In accordance with climate models, and differing from other large upwelling areas of the tropical ocean, a 500,000-yr record of productivity at ODP Site 723 shows consistently stronger upwelling during interglaciations than during glaciations. Sea-surface temperatures (SSTs) reconstructed from the alkenone unsaturation index (UK′37) are high (up to 27°C) during interglaciations and low (22-24°C) during glaciations, indicating a glacial-interglacial temperature change of >3°C in spite of the dampening effect of enhanced or weakened upwelling. The increased productivity is attributed to stronger monsoon winds during interglacial times relative to glacial times, whereas the difference in SSTs must be unrelated to upwelling and to the summer monsoon intensity. The winter (NE) monsoon was more effective in cooling the Arabian Sea during glaciations then it is now.

scholarly journals Advances in Egyptian Mediterranean Coast Climate Change Monitoring

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1870
Author(s):  
Matteo Gentilucci ◽  
Abdelraouf A. Moustafa ◽  
Fagr Kh. Abdel-Gawad ◽  
Samira R. Mansour ◽  
Maria Rosaria Coppola ◽  
...  
Keyword(s):  
Climate Change ◽  
Fish Species ◽  
Mitochondrial Gene ◽  
Mediterranean Coast ◽  
Sea Surface ◽  
Homogeneity Test ◽  
Sea Surface Temperatures ◽  
Climate Trends ◽  
Surface Temperatures ◽  
Lessepsian Species

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.

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

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.

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

2018 ◽  
Vol 14 (6) ◽  
pp. 901-922 ◽  
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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