Subtropical Arctic Ocean temperatures during the Palaeocene/Eocene thermal maximum

Abstract

& the Expedition 302 Scientists †The Palaeocene/Eocene thermal maximum, ,55 million years ago, was a brief period of widespread, extreme climatic warming [1][2][3] , that was associated with massive atmospheric greenhouse gas input 4 . Although aspects of the resulting environmental changes are well documented at low latitudes, no data were available to quantify simultaneous changes in the Arctic region. Here we identify the Palaeocene/Eocene thermal maximum in a marine sedimentary sequence obtained during the Arctic Coring Expedition 5 . We show that sea surface temperatures near the North Pole increased from ,18 8C to over 23 8C during this event. Such warm values imply the absence of ice and thus exclude the influence of ice-albedo feedbacks on this Arctic warming. At the same time, sea level rose while anoxic and euxinic conditions developed in the ocean's bottom waters and photic zone, respectively. Increasing temperature and sea level match expectations based on palaeoclimate model simulations 6 , but the absolute polar temperatures that we derive before, during and after the event are more than 10 8C warmer than those model-predicted. This suggests that higher-than-modern greenhouse gas concentrations must have operated in conjunction with other feedback mechanisms-perhaps polar stratospheric clouds 7 or hurricane-induced ocean mixing 8 -to amplify early Palaeogene polar temperatures.

Anoxia and high primary production in the Paleogene central Arctic Ocean: First detailed records from Lomonosov Ridge

“…The oldest one represents the PETM event already described in detail elsewhere [Pagani et al, 2006;Sluijs et al, 2006] and probably associated with a massive greenhouse gas input [Dickens et al, 1995]. A second similar event, although of smaller magnitude, occurs at about 368 mcd (early Eocene) and may correlate with the ''Elmo Event'' probably representing another global thermal maximum [Lourens et al, 2005].…”

“…Whereas recent papers on ACEX material were restricted to short-term events such as the global Paleocene/Eocene Thermal Maximum (PETM) event [Pagani et al, 2006;Sluijs et al, 2006] and the middle Eocene ''Azolla'' freshwater event , we investigated the entire 200 m thick Paleogene sequence of the ACEX record (200 and 405 mcd (meters composite depth)) (Figure 2). This interval consists of organic-carbonrich sediments, mainly representing the late Paleocene to middle Eocene, i.e., a time interval when the Arctic Ocean was still quite isolated from the world ocean (Figure 1).…”

Warming and environmental changes in the eastern North Sea Basin during the Palaeocene–Eocene Thermal Maximum as revealed by biomarker lipids

“…50% of benthic foraminiferal species references cited therein), and a decrease in water column oxygen concentrations in deep oceans, coastal settings and isolated basins (e.g. Sluijs et al, 2006 andChun et al, 2010;Nicolo et al, 2010). It is further associated with a massive release of 13 C-depleted carbon to the oceans and atmosphere as reflected by a negative carbon isotope excursion (CIE) of >2.5 ‰ (e.g.…”

“…So far, TEX86 palaeothermometry has been applied to a limited number of PETM sections (Hollis et al, 2012;Sluijs et al, 2006Sluijs et al, , 2007Sluijs et al, , 2011Sluijs et al, , 2014Zachos et al, 2006) covering only a few locations worldwide, whereas a PETM MAT record based on the MBT/CBT proxy is available only for a single site located in the Arctic Ocean (Weijers et al, 2007a). The temperature records based on TEX86 show a similar extent of warming as those recorded by Mg/Ca and δ 18 O of foraminifera, i.e.…”

Climate modelling and deep-time climate change

“…Oxygen isotope proxies indicate that benthic temperatures (which refl ect high-latitude annual mean ocean surface conditions) could have been as high as 12 °C (Zachos et al, 2001 ). Direct reconstruction of Arctic ocean surface temperatures using the TEX86 proxy suggest values as high as 19 °C (Sluijs et al, 2006 ). High-latitude continental interiors were also much warmer than today (Greenwood and Wing, 1995 ).…”