Global Extent of Early Eocene Hyperthermal Events: A New Pacific Benthic Foraminiferal Isotope Record From Shatsky Rise (ODP Site 1209)

Self Cite

121

161

The Late Cretaceous–Early Paleogene is the most recent period in Earth history that experienced sustained global greenhouse warmth on multimillion year timescales. Yet, knowledge of ambient climate conditions and the complex interplay between various forcing mechanisms are still poorly constrained. Here we present a 14.75 million‐year‐long, high‐resolution, orbitally tuned record of paired climate change and carbon‐cycling for this enigmatic period (~67–52 Ma), which we compare to an up‐to‐date compilation of atmospheric pCO2 records. Our climate and carbon‐cycling records, which are the highest resolution stratigraphically complete records to be constructed from a single marine site in the Atlantic Ocean, feature all major transient warming events (termed “hyperthermals”) known from this time period. We identify eccentricity as the dominant pacemaker of climate and the carbon cycle throughout the Late Maastrichtian to Early Eocene, through the modulation of precession. On average, changes in the carbon cycle lagged changes in climate by ~23,000 years at the long eccentricity (405,000‐year) band, and by ~3,000–4,500 years at the short eccentricity (100,000‐year) band, suggesting that light carbon was released as a positive feedback to warming induced by orbital forcing. Our new record places all known hyperthermals of the Late Maastrichtian–Early Eocene into temporal context with regards to evolving ambient climate of the time. We constrain potential carbon cycle influences of Large Igneous Province volcanism associated with the Deccan Traps and North Atlantic Igneous Province, as well as the sensitivity of climate and the carbon‐cycle to the 2.4 million‐year‐long eccentricity cycle.

Section: Resultsmentioning

confidence: 99%

A High‐Fidelity Benthic Stable Isotope Record of Late Cretaceous–Early Eocene Climate Change and Carbon‐Cycling

Barnet

Littler

Westerhold

et al. 2019

Self Cite

121

161

“…(a) Late Paleocene‐Early Eocene (LPEE) benthic δ 13 C and δ 18 O records from ODP Sites 1209 (red and orange) and 1262 (blue and light blue), compiled by and placed on the age model of Westerhold et al () and Barnet et al (), respectively. (b) Benthic δ 13 C and δ 18 O records during Eocene Thermal Maximum 2 (ETM‐2) from ODP Sites 1209 (closed red and orange circles; Harper et al, ; McCarren, ), 1210 (open red and orange circles; this study), and 1265 (blue and light blue lines; Stap, Lourens, Thomas, et al, ).…”

Section: Resultsmentioning

confidence: 99%

The Magnitude of Surface Ocean Acidification and Carbon Release During Eocene Thermal Maximum 2 (ETM‐2) and the Paleocene‐Eocene Thermal Maximum (PETM)

Harper

Hönisch

Zeebe

et al. 2020

Self Cite

Eocene Thermal Maximum 2 (ETM‐2; 54.1 Ma) was the second largest Eocene hyperthermal. Like the Paleocene‐Eocene Thermal Maximum (PETM), ETM‐2 was characterized by massive carbon emissions and several degrees of global warming and thus can serve as a case study for assessing the impacts of rapid CO2 emissions on ocean carbonate chemistry, biota, and climate. Marine carbonate records of ETM‐2 are better preserved than those of the PETM due to more subdued carbonate dissolution. As yet, however, the magnitude of this carbon cycle perturbation has not been well constrained. Here, we present the first records of surface ocean acidification for ETM‐2, based on stable boron isotope records in mixed‐layer planktic foraminifera from two midlatitude ODP sites (1210 in the North Pacific and 1265 in the SE Atlantic), which indicate conservative minimum global sea surface acidification of −0.20 +0.12/−0.13 pH units. Using these estimates of pH and temperature as constraints on carbon cycle model simulations, we conclude that the total mass of C, released over a period of 15 to 25 kyr during ETM‐2, likely ranged from 2,600 to 3,800 Gt C, which is greater than previously estimated on the basis of other observations (i.e., stable carbon isotopes and carbonate compensation depth) alone.

“…We provide one of few available reconstructions of oceanic conditions and marine biota over a hyperthermal event occurring early within the period of peak of early Eocene warmth, the EECO, when the progressive warming of deep waters reached its acme (e.g., Lauretano et al, ; Littler et al, ). Peak EECO occurred about 1 Myr after ETM3 (Galeotti et al, ; Kirtland‐Turner et al, ; Lauretano et al, ; Westerhold, Röhl, Donner, et al, ). Our benthic oxygen isotope values are on average ~0.5‰ lower than those for ETM2, which occurred about 1 Myr earlier (Stap, Lourens, Thomas, et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…The Earth's surface warmed from the late Paleocene (58 Ma) into the early Eocene then remained warm through the Early Eocene Climate Optimum (EECO; e.g., Cramer et al, ; Dallanave et al, ; Lauretano et al, , ; Littler et al, ; Westerhold, Röhl, Donner, et al, ; Westerhold, Röhl, Wilkens, et al, ; Zachos et al, , ). Superimposed on this temperature rise were transient episodes of warming, or hyperthermal events, of which the most extreme and widely recognized was the Paleocene‐Eocene thermal maximum (PETM; e.g., Giusberti et al, ; Kennett & Stott, ; McInerney & Wing, ; Röhl et al, ; Sluijs et al, ; Thomas & Shackleton, ; Zachos et al, , ).…”

Section: Introductionmentioning

confidence: 99%

“…Lauretano et al () consider ETM3 to have occurred within the early part of EECO, which in their definition started at about 53 Ma. The start of EECO has more recently been dated and defined by Galeotti et al () and Westerhold, Röhl, Donner, et al (). The latter place it at 53.16 Ma, but note that the onset of the EECO cannot be clearly defined globally.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Early Eocene Thermal Maximum 3: Biotic Response at Walvis Ridge (SE Atlantic Ocean)

Thomas

Galazzo

Balestra

et al. 2018

Self Cite

We combine stable isotope, calcareous nannoplankton, and benthic foraminiferal records for Ocean Drilling Program Sites 1262 (paleodepth ~3,500 m) and 1263 (paleodepth ~1,500 m) on Walvis Ridge (SE Atlantic), to document the marine biotic response to Eocene Thermal Maximum 3, in the early part of the Early Eocene Climate Optimum, ~3.1 Myr after the Paleocene/Eocene Thermal Maximum. Bottom water warming may have decreased the vertical thermal gradient at both sites, but more at Site 1263 than at Site 1262. Floral and faunal changes were more muted at Site 1262 than at shallower Site 1263, indicating that carbonate dissolution was not the most important cause of biotic effects. Assemblage changes were more pronounced in benthos than in plankton. Calcareous nannofossils underwent minor ecological changes, possibly related to the presence of warmer waters, especially at Site 1263, and dissolution‐resistant taxa increased in abundance. Benthic foraminiferal diversity decreased at both sites, but benthic foraminiferal accumulation rates declined dramatically at Site 1263, remaining stable at Site 1262. Ocean circulation may have changed during ETM3, resulting in the presence of a warmer (intermediate) water mass at Site 1263. More pronounced warming may have caused enhanced remineralization of organic matter, so less food reached the benthos. The biotic response to the X‐event was less pronounced than that to earlier and more severe hyperthermal events, the Paleocene/Eocene Thermal Maximum and Eocene Thermal Maximum 2. The extent of the biotic response reflects the severity of the environmental disturbance but varies by location (e.g., paleodepth on Walvis Ridge).