Antarctic surface temperature and elevation during the Last Glacial Maximum

Buizert, Christo; Fudge, T. J.; Roberts, William H. G.; Steig, Eric J.; Sherriff‐Tadano, Sam; Ritz, Catherine; Lefebvre, E.; Edwards, Jon S.; Kawamura, Kenji; Oyabu, Ikumi; Motoyama, Hideaki; Kahle, Emma C.; Jones, Tyler R.; Abe‐Ouchi, Ayako; Obase, Takashi; Martín, Carlos; Corr, Hugh; Severinghaus, Jeffrey P.; Beaudette, Ross; Epifanio, Jenna; Brook, Edward J.; Martin, Kaden; Chappellaz, J.; Aoki, Shuji; Nakazawa, Takakiyo; Sowers, Todd; Alley, Richard B.; Ahn, Jinho; Sigl, Michael; Severi, Mirko; Dunbar, Nelia W.; Svensson, Anders; Fegyveresi, John M.; He, Chengfei; Liu, Zhengyu; Zhu, Jiang; Otto‐Bliesner, Bette L.; Lipenkov, Vladimir Ya.; Kageyama, Masa; Schwander, Jakob

doi:10.1126/science.abd2897

Cited by 92 publications

(109 citation statements)

References 168 publications

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“…In classical climate-forced densification models the densification rate and thus ∆age is almost entirely determined by surface temperature and accumulation rate. Buizert et al (2021) exploit this to infer past surface temperature from estimates of ∆age and accumulation rate. However, our modelling shows that horizontal strain from large scale ice flow lead to enhanced densification rates and should also be taken into account.…”

Section: Implications For Ice Core Datingmentioning

confidence: 99%

Modeling enhanced firn densification due to strain softening

Oraschewski

Grinsted

2021

Preprint

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Abstract. In the accumulation zone of glaciers and ice sheets snow is transformed into glacial ice by firn densification. Classically, this processes is assumed to solely depend on temperature and overburden pressure which is controlled by the accumulation rate. However, exceptionally thin firn layers have been observed in the high-strain shear margins of ice streams. Previously, it has been proposed that this firn thinning can be explained by an enhancement of firn densification due to the effect of strain softening inherent to power-law creep. This hypothesis has not been validated, and the greater firn densities in the presence of horizontal strain rates have not yet been reproduced by models. Here, we develop a model that corrects the firn densification rate predicted by classical, climate-forced models for the effect of strain softening. With the model it is confirmed that strain softening dominates the firn densification process when high strain rates are present. Firn densities along a cross section of the North-East Greenland ice stream (NEGIS) are reproduced with good agreement, validating the accuracy of the developed model. Finally, it is shown that strain softening has significant implications for ice core dating and that it considerably affects the firn properties over wide areas of the polar ice sheet, even at low strain rates. Therefore, we suggest that, besides temperature and accumulation rate, horizontal strain rates should generally be considered as a forcing parameter in firn densification modelling.

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Section: Implications For Ice Core Datingmentioning

confidence: 99%

Modeling enhanced firn densification due to strain softening

Oraschewski

Grinsted

2021

Preprint

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“…Next, the TALDICE gas-age ice-age difference (∆age) is established empirically by matching abrupt changes in atmospheric CH4 to the WD core; at each match point this provides one discrete ∆age constraint. A dynamical firn densification model based on Herron-Langway firn physics (Herron & Langway, 1980) is then used to interpolate between these empirical ∆age constraints, in order to obtain a gas age scale for all depths (Buizert et al, 2021).…”

Section: Development Of Wd2014 Timescale For Taldicementioning

confidence: 99%

“…The ages on AICC2012 scale were estimated to be 9.4-23.4 ka by using the depth and the WD2014 age of EDC (Bazin et al, 2013a, Buizert et al, 2021. (Severinghaus et al, 2015).…”

Section: Gas and Ice Ages Of Larsen Icementioning

confidence: 99%

Chronostratigraphy of blue ice at the Larsen Glacier in Northern Victoria Land, East Antarctica

Lee

Ahn

et al. 2021

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Abstract. Blue ice areas (BIAs) allow for the collection of large-sized old ice samples in a cost-effective way because deep ice outcrops and make old ice samples available close to the surface. However, most chronostratigraphy studies on blue ice are complicated due to fold and fault structures. Here, we report a simple stratigraphy of ice from the Larsen BIA, Antarctica, making the area valuable for paleoclimate studies. Ice layers defined by dust bands and ground penetration radar (GPR) surveys indicate a monotonic increase in age along the ice flow direction on the downstream side, while the upstream ice exhibits a potential repetition of ages on scales of tens of meters, as shown in the complicated fold structure. Stable water isotopes (δ18Oice and δ2Hice) and components of the occluded air (i.e., CO2, N2O, CH4, δ15N-N2, δ18Oatm (= δ18O-O2), δO2/N2, δAr/N2, 81Kr and 85Kr) were analyzed for surface ice and shallow ice core samples. Correlating δ18Oice, δ18Oatm, and CH4 records of Larsen ice with existing ice core records indicates that the gas age at shallow coring sites ranges between 9.2–23.4 ka BP and ice age for entire surface sampling sites between 5.6–24.7 ka BP. Absolute radiometric 81Kr dating for the two cores confirms the ages within acceptable levels of analytical uncertainty. Our study demonstrates that BIA in northern Victoria Land may help researchers obtain high-quality records for paleoclimate and atmospheric greenhouse gas compositions through the last deglaciation.

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“…The ages on AICC2012 scale were estimated to be 9.4-23.4 ka by using the depth and the WD2014 age of EDC (Bazin et al, 2013a, Buizert et al, 2021. (Rhodes et al, 2017).…”

Antarctic surface temperature and elevation during the Last Glacial Maximum

Cited by 92 publications

References 168 publications

Modeling enhanced firn densification due to strain softening

Modeling enhanced firn densification due to strain softening

Chronostratigraphy of blue ice at the Larsen Glacier in Northern Victoria Land, East Antarctica

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