scholarly journals Productivity feedback did not terminate the Paleocene-Eocene Thermal Maximum (PETM)

2010 ◽  
Vol 6 (2) ◽  
pp. 265-272 ◽  
Author(s):  
A. Torfstein ◽  
G. Winckler ◽  
A. Tripati
Keyword(s):  
Biological Pump ◽  
Accumulation Rates ◽  
Excess Carbon ◽  
Export Production ◽  
Initial Carbon ◽  
Thermal Maximum ◽  
Carbon Release ◽  
Rapid Removal ◽  
Sudden Release ◽  
A Site

Abstract. The Paleocene-Eocene Thermal Maximum (PETM) occurred approximately 55 million years ago, and is one of the most dramatic abrupt global warming events in the geological record. This warming was triggered by the sudden release of thousands of gigatons of carbon into the atmosphere and is widely perceived to be the best analogue for current anthropogenic climate change. Yet, the mechanism of recovery from this event remains controversial. A massive increase in the intensity of the marine biological pump ("productivity feedback") has been suggested to cause a drawdown of atmospheric CO2 and subsequent carbon sequestration in the ocean. A re-evaluation of the "productivity feedback hypothesis", based on biogenic barium mass accumulation rates (Ba-MARs) for a site in the Southern Ocean, finds that any increase in export production lagged the initial carbon release by at least ~70 000 years. This implies that export production did not facilitate rapid removal of excess carbon from the atmosphere. Thus, the most likely mechanism for carbon removal appears to be silicate weathering, which occurred at much slower rates than previously assumed.

scholarly journals Productivity feedback did not terminate the Paleocene-Eocene Thermal Maximum (PETM)

2009 ◽  
Vol 5 (5) ◽  
pp. 2391-2410 ◽  
Author(s):  
A. Torfstein ◽  
G. Winckler ◽  
A. Tripati
Keyword(s):  
Silicate Weathering ◽  
Biological Pump ◽  
Accumulation Rates ◽  
Excess Carbon ◽  
Export Production ◽  
Initial Carbon ◽  
Thermal Maximum ◽  
Carbon Release ◽  
Sudden Release ◽  
A Site

Abstract. The Paleocene-Eocene Thermal Maximum (PETM) occurred approximately 55 million years ago, and is one of the most dramatic abrupt global warming events in the geological record. This warming was triggered by the sudden release of thousands of gigatons of carbon into the atmosphere and is widely perceived to be the best analogue for current anthropogenic climate change. Yet, the mechanism of recovery from this event remains controversial. A massive increase in the intensity of the marine biological pump (''productivity feedback'') has been suggested to cause a drawdown of atmospheric CO2 and subsequent carbon sequestration in the ocean. A re-evaluation of the ''productivity feedback hypothesis'', based on biogenic barium mass accumulation rates (Ba-MARs) for a site in the Southern Ocean, finds that any increase in export production lagged the initial carbon release by at least ~70 000 years. This implies that export production did not rapidly remove excess carbon from the atmosphere, and renders the most likely mechanism for carbon removal to be silicate weathering, at much slower rates than previously assumed.

scholarly journals Scaled biotic disruption during early Eocene global warming events

2012 ◽  
Vol 9 (11) ◽  
pp. 4679-4688 ◽  
Author(s):  
S. J. Gibbs ◽  
P. R. Bown ◽  
B. H. Murphy ◽  
A. Sluijs ◽  
K. M. Edgar ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Threshold Value ◽  
Early Eocene ◽  
Natural Experiments ◽  
Thermal Maximum ◽  
Carbon Release ◽  
Long Time ◽  
Extinction Events ◽  
The Relationship

Abstract. Late Paleocene and early Eocene hyperthermals are transient warming events associated with massive perturbations of the global carbon cycle, and are considered partial analogues for current anthropogenic climate change. Because the magnitude of carbon release varied between the events, they are natural experiments ideal for exploring the relationship between carbon cycle perturbations, climate change and biotic response. Here we quantify marine biotic variability through three million years of the early Eocene that include five hyperthermals, utilizing a method that allows us to integrate the records of different plankton groups through scenarios ranging from background to major extinction events. Our long time-series calcareous nannoplankton record indicates a scaling of biotic disruption to climate change associated with the amount of carbon released during the various hyperthermals. Critically, only the three largest hyperthermals, the Paleocene–Eocene Thermal Maximum (PETM), Eocene Thermal Maximum 2 (ETM2) and the I1 event, show above-background variance, suggesting that the magnitude of carbon input and associated climate change needs to surpass a threshold value to cause significant biotic disruption.

scholarly journals Paleocene/Eocene carbon feedbacks triggered by volcanic activity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sev Kender ◽  
Kara Bogus ◽  
Gunver K. Pedersen ◽  
Karen Dybkjær ◽  
Tamsin A. Mather ◽  
...  
Keyword(s):  
North Atlantic ◽  
Proxy Records ◽  
The North ◽  
The Earth ◽  
Thermal Maximum ◽  
Igneous Province ◽  
Carbon Release ◽  
Carbon Reservoir ◽  
Earth’S Climate ◽  
North Atlantic Igneous Province

AbstractThe Paleocene–Eocene Thermal Maximum (PETM) was a period of geologically-rapid carbon release and global warming ~56 million years ago. Although modelling, outcrop and proxy records suggest volcanic carbon release occurred, it has not yet been possible to identify the PETM trigger, or if multiple reservoirs of carbon were involved. Here we report elevated levels of mercury relative to organic carbon—a proxy for volcanism—directly preceding and within the early PETM from two North Sea sedimentary cores, signifying pulsed volcanism from the North Atlantic Igneous Province likely provided the trigger and subsequently sustained elevated CO2. However, the PETM onset coincides with a mercury low, suggesting at least one other carbon reservoir released significant greenhouse gases in response to initial warming. Our results support the existence of ‘tipping points’ in the Earth system, which can trigger release of additional carbon reservoirs and drive Earth’s climate into a hotter state.

scholarly journals Preliminary results of ionic concentrations in snow pits along the Zhongshan–Dome A traverse route, Antarctica

2004 ◽  
Vol 39 ◽  
pp. 155-160 ◽  
Author(s):  
Ren Jiawen ◽  
Sun Junying ◽  
Qin Dahe
Keyword(s):  
Major Ions ◽  
Concentration Profiles ◽  
Accumulation Rates ◽  
Dome A ◽  
Stable Oxygen Isotope ◽  
Zhongshan Station ◽  
Ionic Concentrations ◽  
Regional Trends ◽  
Stable Oxygen ◽  
A Site

AbstractDuring an inland traverse expedition along the route from Zhongshan station on the coast to Dome A (about 4200ma.s.l.; 1400 km from Zhongshan) in East Antarctica in 1998/99, three snow pits with a depth of 2.1–3.3m were sampled continuously. Snow pits were located at sites 800–1100km from the coast, with altitudes varying from 2850 to 3760 m. The samples were analyzed for stable oxygen isotope and major ions. Seasonal variations in δ18O are not clear, so initial dating was made through comparison of concentration profiles of major ions and then adjusted according to the visible stratigraphy. Generally, average ionic concentrations decrease with increasing altitude and hence distance from the coast, but NH4+ and Ca2+ have relatively high values at a site 1000 km inland. Ionic concentrations tend to increase with depth at lower altitudes, but the opposite is true at higher altitudes. Accumulation rates increase with depth at site DT401 (3760ma.s.l.; 1097 km from Zhongshan) and decrease at DT364 (3380ma.s.l.; 1022 km from Zhongshan) and DT263 (2850ma.s.l.; 820 km from Zhongshan), suggesting that differences in regional trends exist. In all snow pits, Na+ and Cl– concentration profiles have a very good positive correlation. Profiles of nssSO42– in the pits show quite different features. At 3760ma.s.l, no remarkable nssSO42– peaks can be distinguished, but one and three peak sets are quite striking at 3380 and 2850 m, respectively.

scholarly journals Reduced carbon cycle resilience across the Palaeocene–Eocene Thermal Maximum

2018 ◽  
Vol 14 (10) ◽  
pp. 1515-1527 ◽  
Author(s):  
David I. Armstrong McKay ◽  
Timothy M. Lenton
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
Deep Ocean ◽  
Tipping Point ◽  
Tipping Points ◽  
Carbon Burial ◽  
Thermal Maximum ◽  
Organic Carbon Burial ◽  
Carbon Release ◽  
Hyperthermal Events

Abstract. Several past episodes of rapid carbon cycle and climate change are hypothesised to be the result of the Earth system reaching a tipping point beyond which an abrupt transition to a new state occurs. At the Palaeocene–Eocene Thermal Maximum (PETM) at ∼56 Ma and at subsequent hyperthermal events, hypothesised tipping points involve the abrupt transfer of carbon from surface reservoirs to the atmosphere. Theory suggests that tipping points in complex dynamical systems should be preceded by critical slowing down of their dynamics, including increasing temporal autocorrelation and variability. However, reliably detecting these indicators in palaeorecords is challenging, with issues of data quality, false positives, and parameter selection potentially affecting reliability. Here we show that in a sufficiently long, high-resolution palaeorecord there is consistent evidence of destabilisation of the carbon cycle in the ∼1.5 Myr prior to the PETM, elevated carbon cycle and climate instability following both the PETM and Eocene Thermal Maximum 2 (ETM2), and different drivers of carbon cycle dynamics preceding the PETM and ETM2 events. Our results indicate a loss of “resilience” (weakened stabilising negative feedbacks and greater sensitivity to small shocks) in the carbon cycle before the PETM and in the carbon–climate system following it. This pre-PETM carbon cycle destabilisation may reflect gradual forcing by the contemporaneous North Atlantic Volcanic Province eruptions, with volcanism-driven warming potentially weakening the organic carbon burial feedback. Our results are consistent with but cannot prove the existence of a tipping point for abrupt carbon release, e.g. from methane hydrate or terrestrial organic carbon reservoirs, whereas we find no support for a tipping point in deep ocean temperature.

scholarly journals Export production fluctuations in the eastern equatorial Pacific during the Pliocene‐Pleistocene: Reconstruction using barite accumulation rates

2015 ◽  
Vol 30 (11) ◽  
pp. 1455-1469 ◽  
Author(s):  
Zhongwu Ma ◽  
Ana Christina Ravelo ◽  
Zhonghui Liu ◽  
Liping Zhou ◽  
Adina Paytan
Keyword(s):  
Equatorial Pacific ◽  
Accumulation Rates ◽  
Export Production ◽  
Eastern Equatorial Pacific

Carbon sequestration during the Palaeocene–Eocene Thermal Maximum by an efficient biological pump

2014 ◽  
Vol 7 (5) ◽  
pp. 382-388 ◽  
Author(s):  
Zhongwu Ma ◽  
Ellen Gray ◽  
Ellen Thomas ◽  
Brandon Murphy ◽  
James Zachos ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Biological Pump ◽  
Thermal Maximum

scholarly journals Rapid shifts in circulation and biogeochemistry of the Southern Ocean during deglacial carbon cycle events

2020 ◽  
Vol 6 (42) ◽  
pp. eabb3807
Author(s):  
Tao Li ◽  
Laura F. Robinson ◽  
Tianyu Chen ◽  
Xingchen T. Wang ◽  
Andrea Burke ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Ocean Circulation ◽  
Deep Sea ◽  
Deep Ocean ◽  
Biological Pump ◽  
Last Deglaciation ◽  
Proxy Data ◽  
Ocean Ventilation ◽  
Carbon Release ◽  
The Last Deglaciation

The Southern Ocean plays a crucial role in regulating atmospheric CO2 on centennial to millennial time scales. However, observations of sufficient resolution to explore this have been lacking. Here, we report high-resolution, multiproxy records based on precisely dated deep-sea corals from the Southern Ocean. Paired deep (∆14C and δ11B) and surface (δ15N) proxy data point to enhanced upwelling coupled with reduced efficiency of the biological pump at 14.6 and 11.7 thousand years (ka) ago, which would have facilitated rapid carbon release to the atmosphere. Transient periods of unusually well-ventilated waters in the deep Southern Ocean occurred at 16.3 and 12.8 ka ago. Contemporaneous atmospheric carbon records indicate that these Southern Ocean ventilation events are also important in releasing respired carbon from the deep ocean to the atmosphere. Our results thus highlight two distinct modes of Southern Ocean circulation and biogeochemistry associated with centennial-scale atmospheric CO2 jumps during the last deglaciation.

scholarly journals Seismic Refraction and Reflection Measurements at “Byrd” Station, Antarctica

1973 ◽  
Vol 12 (64) ◽  
pp. 101-111 ◽  
Author(s):  
Heinz Kohnen ◽  
Charles R. Bentley
Keyword(s):  
Seismic Refraction ◽  
Drill Hole ◽  
Snow Accumulation ◽  
Angle Of Incidence ◽  
Accumulation Rates ◽  
Mean Velocity ◽  
The Difference ◽  
Good Determination ◽  
Ice Fabrics ◽  
A Site

Abstract Seismic refraction and reflection shooting was carried out along three profiles about 10 km long, angled 60° to one another, near “Byrd” station, Antarctica, during the 1970–71 field season. No dependence of velocity upon azimuth was found, but velocities at 200 or 300 m depth were slightly greater than at a site 30 km away where measurements were made in 1958. The difference can probably be attributed to different ice fabrics arising from a 50% difference in snow accumulation rates at the two sites. The velocity depth and density–velocity functions at the two sites are also significantly different, but close agreement was found at each site between the depths to significant changes in the velocity gradient and the depths of fundamental change in the densification process. Such agreement may permit density–depth curves, and consequently accumulation rates, to be measured by seismic refraction shooting alone. The reflection shooting on a common reflection-point profile led to a good determination of mean velocity through the ice as a function of angle of incidence. The results agree closely with similar measurements at the 1958 site, and with an anisotropic model based on glaciological and sonic logging observations in the deep drill hole. The mean vertical velocity of 3.90–3.93 km/s through the solid ice is about 2% higher than has commonly been used for determinations of ice thickness from seismic reflection shooting.

scholarly journals Increased export production during recovery from the Paleocene–Eocene thermal maximum constrained by sedimentary Ba isotopes

2019 ◽  
Vol 510 ◽  
pp. 53-63 ◽  
Author(s):  
Luke Bridgestock ◽  
Yu-Te Hsieh ◽  
Donald Porcelli ◽  
Gideon M. Henderson
Keyword(s):  
Export Production ◽  
Thermal Maximum
Sign in / Sign up

Export Citation Format

Share Document