Seasonal variability in Arctic temperatures during early Eocene time

Eberle, Jaelyn J.; Fricke, Henry C.; Humphrey, John; Hackett, Logan; Newbrey, Michael G.; Hutchison, J. Howard

doi:10.1016/j.epsl.2010.06.005

Cited by 82 publications

(88 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It is thought that some proxies may have a bias towards summer temperatures, e.g. the MBT-CBT proxy (Eberle et al, 2010). In addition, many of the species of foraminifera used to infer palaeoclimate are extinct, so it is impossible to know whether the values recorded by them are equilibrium values (Roberts et al, 2009).…”

Section: Sea Surface Temperaturesmentioning

confidence: 99%

Investigating vegetation–climate feedbacks during the early Eocene

2014

View full text Add to dashboard Cite

Abstract. Evidence suggests that the early Eocene was a time of extreme global warmth. However, there are discrepancies between the results of many previous modelling studies and the proxy data at high latitudes, with models struggling to simulate the shallow temperature gradients of this time period to the same extent as the proxies indicate. Vegetation-climate feedbacks play an important role in the present day, but are often neglected in these palaeoclimate modelling studies, and this may be a contributing factor to resolving the model-data discrepancy.Here we investigate these vegetation-climate feedbacks by carrying out simulations of the early Eocene climate at 2 × and 4 × pre-industrial atmospheric CO 2 with fixed vegetation (homogeneous shrubs everywhere) and dynamic vegetation.The results show that the simulations with dynamic vegetation are warmer in the global annual mean than the simulations with fixed shrubs by 0.9 • C at 2 × and 1.8 • C at 4 ×. Consequently, the warming when CO 2 is doubled from 2 × to 4 × is 1 • C higher (in the global annual mean) with dynamic vegetation than with fixed shrubs. This corresponds to an increase in climate sensitivity of 26 %. This difference in warming is enhanced at high latitudes, with temperatures increasing by over 50 % in some regions of Antarctica. In the Arctic, ice-albedo feedbacks are responsible for the majority of this warming. On a global scale, energy balance analysis shows that the enhanced warming with dynamic vegetation is mainly associated with an increase in atmospheric water vapour but changes in clouds also contribute to the temperature increase. It is likely that changes in surface albedo due to changes in vegetation cover resulted in an initial warming which triggered these water vapour feedbacks.In conclusion, dynamic vegetation goes some way to resolving the discrepancy, but our modelled temperatures cannot reach the same warmth as the data suggest in the Arctic. This suggests that there are additional mechanisms, not included in this modelling framework, behind the polar warmth or that the proxies have been misinterpreted.

show abstract

Section: Sea Surface Temperaturesmentioning

confidence: 99%

Investigating vegetation–climate feedbacks during the early Eocene

2014

View full text Add to dashboard Cite

show abstract

“…Based largely on paleoclimate proxy data from the eastern and central Arctic, early -middle Eocene Arctic climate in this region has been characterized as having warm, wet summers and mild winters [9], [10], [34], [35] [36]. High-resolution carbon isotope analysis across tree rings in mummified wood from Muskox River on northern Banks Island (,50 km south of the Eames River locality) and Stenkul Fiord on southern Ellesmere Island allow the reconstruction of seasonal precipitation patterns in the Eocene Arctic [37].…”

Section: Discussionmentioning

confidence: 99%

First FossilAlligatorfrom the Late Eocene of Nebraska and the Late Paleogene Record of Alligators in the Great Plains

Whiting

Hastings

2015

Journal of Herpetology

View full text Add to dashboard Cite

Background: Discovery of Eocene non-marine vertebrates, including crocodylians, turtles, bony fishes, and mammals in Canada's High Arctic was a critical paleontological contribution of the last century because it indicated that this region of the Arctic had been mild, temperate, and ice-free during the early -middle Eocene (,53-50 Ma), despite being well above the Arctic Circle. To date, these discoveries have been restricted to Canada's easternmost Arctic -Ellesmere and Axel Heiberg Islands (Nunavut). Although temporally correlative strata crop out over 1,000 km west, on Canada's westernmost Arctic Island -Banks Island, Northwest Territories -they have been interpreted as predominantly marine. We document the first Eocene bony fish and crocodyliform fossils from Banks Island.

show abstract

“…Estimates of early-middle Eocene Arctic mean annual temperature range from 8 to 15°C, summers probably reached 19-25°C, and winters were above freezing (Eberle et al 2010;Eberle and Greenwood 2012). Based upon carbon isotope analysis of mummified wood from the Cyclic Member near Muskox River on northern Banks Island, Schubert et al (2012) concluded that the Eocene forests on Northern Banks experienced three times more precipitation during summer than during winter, a seasonal pattern analogous to today's temperate forests of eastern Asia.…”

Section: Geologic Setting and Agementioning

confidence: 99%

“…The fossils described below were collected over the course of three field seasons (2004, 2010 that sample Eocene strata near the Eames River inside Aulavik National Park on northern Banks Island, Northwest Territories, Canada (approximately 74°10′N, 120°45-46′W, approximately 76°N paleolatitude according to GEOMAR data) (Fig. 1).…”

Section: Geologic Setting and Agementioning

confidence: 99%

New records from Banks Island expand the diversity of Eocene fishes from Canada’s western Arctic Greenhouse

Gottfried

Eberle

2017

Arctic Science

View full text Add to dashboard Cite

Eocene vertebrates from the Canadian Arctic, including sharks, bony fishes, turtles, crocodylians, birds, and mammals, have provided strong evidence for relatively warm ice-free conditions in the Arctic during the Eocene Greenhouse interval. Recent expeditions to Banks Island (Northwest Territories) in the western Arctic have recovered a relatively more marine-influenced Eocene fauna, including sand tiger sharks, bony fishes, turtle shell fragments, and a single crocodylian specimen. We report here on new additions to this fauna, including diagnostic large scales that confirm the presence of Amia in the western Arctic. One very large lateral line scale corresponds to a fish approximately 1.4 m in total length, larger than the maximum size for extant Amia calva. We also recovered approximately 100 distinctive teeth that we assign to the teleost genus Eutrichiurides, which is otherwise known from lower latitude Paleogene sites in the United States, India, Africa, and Europe. The genus is interpreted as an ambush predator in shallow marine environments, consistent with the inferred Eocene paleoenvironment of Banks Island. The presence of Eutrichiurides in the Arctic adds a distinctive new element to the Eocene Greenhouse fauna and is intriguing with respect to the biogeography and dispersal capabilities of this taxon.Key words: Eocene, Arctic, greenhouse, climate optimum, Banks Island, fishes, Amia, Eutrichiurides.Résumé : Les vertébrés éocènes de l'Arctique canadien, y compris les requins, les poissons osseux, les tortues, les crocodiliens, les oiseaux et les mammifères, fournissent une preuve solide indiquant des conditions sans glace relativement chaudes dans l'Arctique pendant l'intervalle de « serre éocène ». Les expéditions récentes à l'île Banks aux Territoires du Nord-Ouest dans la région ouest de l'Arctique ont récupéré une faune éocène plutôt d'influence marine, y compris des requins-taureaux, des poissons osseux, des fragments d'écailles de tortue et un seul spécimen crocodilien. Nous faisons rapport ici de nouveaux ajouts à cette faune, y compris des grandes écailles diagnostiques qui confirment la présence d'Amia dans la région ouest de l'Arctique. Une très grande écaille de la ligne latérale correspond à un poisson d'environ 1,4 m de longueur totale, plus grand que la taille maximale pour le genre Amia calva existant. Nous avons aussi récupéré à peu près 100 dents distinctives que nous attribuons au genre téléostéen Eutrichiurides, beaucoup plus connu aux sites de latitude inférieure de Paléogène aux États-Unis, en Inde, en Afrique et en Europe. Le genre est considéré comme un prédateur d'embuscade dans les milieux marins peu

show abstract

Seasonal variability in Arctic temperatures during early Eocene time

Cited by 82 publications

References 32 publications

Investigating vegetation–climate feedbacks during the early Eocene

Investigating vegetation–climate feedbacks during the early Eocene

First FossilAlligatorfrom the Late Eocene of Nebraska and the Late Paleogene Record of Alligators in the Great Plains

New records from Banks Island expand the diversity of Eocene fishes from Canada’s western Arctic Greenhouse

Contact Info

Product

Resources

About