Greenland temperature response to climate forcing during the last deglaciation

Buizert, Christo; Gkinis, Vasileios; Severinghaus, Jeffrey P.; He, Feng; Lecavalier, Benoit; Kindler, Philippe; Leuenberger, Markus; Carlson, Anders E.; Vinther, Bo M.; Masson‐Delmotte, Valérie; White, James W. C.; Liu, Zhengyu; Otto‐Bliesner, Bette L.; Brook, Edward J.

doi:10.1126/science.1254961

Cited by 256 publications

(309 citation statements)

References 95 publications

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“…2B) indicates that the surface in central West Antarctica was colder during the LGM (average from 20 ka to 23 ka) than in the late Holocene by 11.3 ± 1.8 • C (2σ) (Table S3), whereas the net warming from the LGM to the middle Holocene thermal maximum (3-6 ka at this site) was perhaps as large as 13.7 (6,12,26). It is possible that there exists a real regional difference from West Antarctica, where the climate is more strongly influenced by the proximal ocean (24,27), but these values all derive from assumptions about the sensitivity of ice isotopes to climatic temperature, a method known to be inaccurate in Greenland (10,28).…”

Section: Discussionmentioning

confidence: 90%

Deglacial temperature history of West Antarctica

Cuffey

Clow

Steig

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The most recent glacial to interglacial transition constitutes a remarkable natural experiment for learning how Earth's climate responds to various forcings, including a rise in atmospheric CO 2 . This transition has left a direct thermal remnant in the polar ice sheets, where the exceptional purity and continual accumulation of ice permit analyses not possible in other settings. For Antarctica, the deglacial warming has previously been constrained only by the water isotopic composition in ice cores, without an absolute thermometric assessment of the isotopes' sensitivity to temperature. To overcome this limitation, we measured temperatures in a deep borehole and analyzed them together with ice-core data to reconstruct the surface temperature history of West Antarctica. The deglacial warming was 11.3 ± 1.8 • C, approximately two to three times the global average, in agreement with theoretical expectations for Antarctic amplification of planetary temperature changes. Consistent with evidence from glacier retreat in Southern Hemisphere mountain ranges, the Antarctic warming was mostly completed by 15 kyBP, several millennia earlier than in the Northern Hemisphere. These results constrain the role of variable oceanic heat transport between hemispheres during deglaciation and quantitatively bound the direct influence of global climate forcings on Antarctic temperature. Although climate models perform well on average in this context, some recent syntheses of deglacial climate history have underestimated Antarctic warming and the models with lowest sensitivity can be discounted.climate | paleoclimate | Antarctica | glaciology | temperature F rom the Last Glacial Maximum (LGM) around 21 ka to the middle of the Holocene, increased greenhouse gas concentrations and reduced reflectivities of the surface and atmosphere directly increased the uptake of energy to Earth's climate system by about 7W·m −2 (1-3) and warmed the surface by 3-6 • C on average (4-7). Although contributing little to this global average because of the comparatively small area involved, the warming in polar regions holds particular interest. In addition to driving changes of ice sheets, permafrost, and hydrology and modulating oceanic and atmospheric circulations, polar warming partly controlled both the evolution of surface reflectivity and the transfer of carbon dioxide from ocean to atmosphere and hence the climate forcing itself. Further, reconstructions of polar warming during deglaciation permit quantification of one key prediction of climate theory-that feedback processes amplify temperature changes in polar regions relative to the global average (4, 8, 9), a phenomenon referred to as polar amplification. Arctic data reveal a warming three to four times the global average based on a wide variety of indicators (6), including combined analyses of ice-core data and borehole temperatures (10, 11). Limited available constraints suggest a smaller but still amplified Antarctic warming, roughly 1.5 to 2.5 times greater than the global average (6, 12). T...

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Section: Discussionmentioning

confidence: 90%

Deglacial temperature history of West Antarctica

Cuffey

Clow

Steig

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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125

141

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“…(top) Greenland and (bottom) North American temperatures in the F‐21k experiment (black), T‐21k experiment (red; CCSM3), and the GISP2 temperature reconstruction (green) [ Buizert et al ., 2014]. The T‐21k Greenland temperature is shifted by −9°C to reflect elevation difference between the T‐21k simulation and GISP2.…”

Section: Methodsmentioning

confidence: 99%

“…Meltwater Pulse 1a (MWP1a) is the largest of these, identified as a 14–18 m of GMSLR in less than 340 years at 14.6 ka [ Deschamps et al ., 2012] in coral reef records from Tahiti and Barbados, as well as other sea level proxies around the world. This event also occurred around the time of an abrupt Northern Hemisphere warming of 4–5°C that took place within a few decades to centuries [ Buizert et al ., 2014; Deschamps et al ., 2012]. However, the link between this intense ice melt and warming remains elusive.…”

Section: Introductionmentioning

confidence: 99%

Abrupt Bølling warming and ice saddle collapse contributions to the Meltwater Pulse 1a rapid sea level rise

Gregoire

Otto‐Bliesner

Valdes

et al. 2016

Geophysical Research Letters

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Elucidating the source(s) of Meltwater Pulse 1a, the largest rapid sea level rise caused by ice melt (14–18 m in less than 340 years, 14,600 years ago), is important for understanding mechanisms of rapid ice melt and the links with abrupt climate change. Here we quantify how much and by what mechanisms the North American ice sheet could have contributed to Meltwater Pulse 1a, by driving an ice sheet model with two transient climate simulations of the last 21,000 years. Ice sheet perturbed physics ensembles were run to account for model uncertainties, constraining ice extent and volume with reconstructions of 21,000 years ago to present. We determine that the North American ice sheet produced 3–4 m global mean sea level rise in 340 years due to the abrupt Bølling warming, but this response is amplified to 5–6 m when it triggers the ice sheet saddle collapse.

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“…Most of these records are Holocene in age and postdate the primary melting phase of the LIS during Termination I. As a result, these are likely to yield estimates of LIS d 18 O that are more positive than LGM values, following the climate signal that is seen in Greenland when comparing Holocene ice (À26 to À36‰; Vinther et al, 2009) to LGM ice (À40 to À45‰; Buizert et al, 2014;Johnsen et al, 1972;Seierstad et al, 2014). The most direct measurements of LIS remnants, from ice on the Barnes Ice Cap, yield d 18 O values of À21 to À40‰ (Hooke and Clausen, 1982) at a high-latitude site (70 N) on Baffin Island proximal to a marine isotopic source (Andrews et al, 2002).…”

Section: Lis Melting Historymentioning

confidence: 99%

Oxygen isotope geochemistry of Laurentide ice-sheet meltwater across Termination I

Vetter

Spero

Eggins

et al. 2017

Quaternary Science Reviews

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a b s t r a c tWe present a new method that quantifies the oxygen isotope geochemistry of Laurentide ice-sheet (LIS) meltwater across the last deglaciation, and reconstruct decadal-scale variations in the d 18 O of LIS meltwater entering the Gulf of Mexico between~18 and 11 ka. We employ a technique that combines laser ablation ICP-MS (LA-ICP-MS) and oxygen isotope analyses on individual shells of the planktic values of Mississippi River discharge from discrete core intervals range from À22‰ to À38‰ VSMOW. These values suggest a dynamic melting history of different parts of the LIS, with potential contributions to Mississippi River outflow from both the low-elevation, southern margin of the LIS and high-elevation, high-latitude domes in the LIS interior that were transported to the ablation zone. Prior to~15.5 ka, the d 18 O water value of the Mississippi River was similar to that of regional precipitation or low-latitude LIS meltwater, but the Ba concentration in the Mississippi basin was affected by changes in weathering within the watershed, complicating Ba-salinity relationships in the Gulf of Mexico. After 13 ka, our data suggest Mississippi River outflow did not influence surface salinity above our Gulf of Mexico Orca Basin core site. Rather, we hypothesize that open ocean conditions prevailed as sea level rose and the paleoshoreline at the southern edge of North America retreated northward.

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Greenland temperature response to climate forcing during the last deglaciation

Cited by 256 publications

References 95 publications

Deglacial temperature history of West Antarctica

Deglacial temperature history of West Antarctica

Abrupt Bølling warming and ice saddle collapse contributions to the Meltwater Pulse 1a rapid sea level rise

Oxygen isotope geochemistry of Laurentide ice-sheet meltwater across Termination I

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