Climatic interpretation of the recently extended Vostok ice records

Jouzel, Jean; Waelbroeck, Claire; Malaizé, Bruno; Bender, Michael L.; Petit, Jean‐Robert; Stiévenard, M.; Barkov, N. I.; Barnola, Jean-Marc; King, T.; Kotlyakov, V. M.; Lipenkov, V. Ya.; Lorius, C.; Raynaud, Dominique; Ritz, Catherine; Sowers, Todd

doi:10.1007/bf00207935

Cited by 151 publications

(55 citation statements)

References 52 publications

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“…The most closely related ice core parameter is δ 18 O atm , δ 18 O of atmospheric O 2 . Ice core records of δ 18 O atm are strongly correlated with variations of insolation in the precession band, with a lag assumed to be ∼ 5-6 ka as established for the last termination (glacial-interglacial transition, Bender et al, 1994;Jouzel et al, 1996;Petit et al, 1999;Shackleton et al, 2000;Dreyfus et al, 2007). The modulation of δ 18 O atm by precession operates through the biosphere productivity and changes in low-latitude water cycle (Bender et al, 1994;Malaizé et al, 1999;Wang et al, 2008;Severinghaus et al, 2009;Landais et al, 2007Landais et al, , 2010.…”

Section: Introductionmentioning

confidence: 99%

“…Because of these complex interactions, the lag between δ 18 O atm and precession should vary with time (Leuenberger, 1997;Jouzel et al, 2002). However, for dating purposes, this lag has been assumed to be constant with an uncertainty of a quarter of a precession cycle (6 ka; Jouzel et al, 1996;Parrenin et al, 2001Parrenin et al, , 2007Dreyfus et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Phase relationships between orbital forcing and the composition of air trapped in Antarctic ice cores

et al. 2016

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Abstract. Orbital tuning is central for ice core chronologies beyond annual layer counting, available back to 60 ka (i.e. thousands of years before 1950) for Greenland ice cores. While several complementary orbital tuning tools have recently been developed using δ 18 O atm , δO 2 /N 2 and air content with different orbital targets, quantifying their uncertainties remains a challenge. Indeed, the exact processes linking variations of these parameters, measured in the air trapped in ice, to their orbital targets are not yet fully understood. Here, we provide new series of δO 2 /N 2 and δ 18 O atm data encompassing Marine Isotopic Stage (MIS) 5 (between 100 and 160 ka) and the oldest part (340-800 ka) of the East Antarctic EPICA Dome C (EDC) ice core. For the first time, the measurements over MIS 5 allow an inter-comparison of δO 2 /N 2 and δ 18 O atm records from three East Antarctic ice core sites (EDC, Vostok and Dome F). This comparison highlights some site-specific δO 2 /N 2 variations. Such an observation, the evidence of a 100 ka periodicity in the δO 2 /N 2 signal and the difficulty to identify extrema and mid-slopes in δO 2 /N 2 increase the uncertainty associated with the use of δO 2 /N 2 as an orbital tuning tool, now calculated to be 3-4 ka. When combining records of δ 18 O atm and δO 2 /N 2 from Vostok and EDC, we find a loss of orbital signature for these two parameters during periods of minimum eccentricity (∼ 400 ka, ∼ 720-800 ka). Our data set reveals a time-varying offset between δO 2 /N 2 and δ 18 O atm records over the last 800 ka that we interpret as variations in the lagged response of δ 18 O atm to precession. The largest offsets are identified during Terminations II, MIS 8 and MIS 16, corresponding to periods of destabilization of the Northern polar ice sheets. We therefore suggest that the occurrence of Heinrich-like events influences the response of δ 18 O atm to precession.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phase relationships between orbital forcing and the composition of air trapped in Antarctic ice cores

et al. 2016

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“…For its spin-up, the ISM was initialisated with a simulation of the last two glacial cycles until year 3000 BP, with a time-dependent signal from the ice cores of GRIP (Dansgaard et al 1993) and VOSTOK (Jouzel et al , 1996 for the northern and southern hemisphere ice sheets, respectively, superimposed to the spatial pattern given by the present-day climatology of ERA40 (Uppala et al 2005). A linear relationship between temperature and precipitation changes has been used for precipitation forcing (Greve et al 1999).…”

Section: Set-up Of Simulationsmentioning

confidence: 99%

Climate modification by future ice sheet changes and consequences for ice sheet mass balance

et al. 2009

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The future evolution of global ice sheets under anthropogenic greenhouse forcing and its impact on the climate system, including the regional climate of the ice sheets, are investigated with a comprehensive earth system model consisting of a coupled Atmosphere-Ocean General Circulation Model, a dynamic vegetation model and an ice sheet model. The simulated control climate is realistic enough to permit a direct coupling of the atmosphere and ice sheet components, avoiding the use of anomaly coupling, which represents a strong improvement with respect to previous modelling studies. Glacier ablation is calculated with an energy-balance scheme, a more physical approach than the commonly used degree-day method. Modifications of glacier mask, topographic height and freshwater fluxes by the ice sheets influence the atmosphere and ocean via dynamical and thermodynamical processes. Several simulations under idealized scenarios of greenhouse forcing have been performed, where the atmospheric carbon dioxide stabilizes at two and four times pre-industrial levels. The evolution of the climate system and the ice sheets in the simulations with interactive ice sheets is compared with the simulations with passively coupled ice sheets. For a four-times CO 2 scenario forcing, a faster decay rate of the Greenland ice sheet is found in the non-interactive case, where melting rates are higher. This is caused by overestimation of the increase in near-surface temperature that follows the reduction in topographic height. In areas close to retreating margins, melting rates are stronger in the interactive case, due to changes in local albedo. Our results call for careful consideration of the feedbacks operating between ice sheets and climate after substantial decay of the ice sheets.

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“…We report the results with an artificial environment (Figure 1) and one based on the Vostok ice core data [25], [26] (see next Section). In order to make the different environments comparable, we normalize them so the the minimum environmental value is and the maximum environmental value is .…”

Section: Models and Resultsmentioning

confidence: 99%

“…To address this issue, we insert a more realistic timeseries in the form of the Vostok ice core data [25], [26]. This data indicates that the temperature environment over the last 400 000 years has been characterized by rapid deglaciation events, interspersed across periods of slower cooling and cold plateaus.…”

Section: Models and Resultsmentioning

confidence: 99%

Choosing Fitness-Enhancing Innovations Can Be Detrimental under Fluctuating Environments

2011

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The ability to predict the consequences of one's behavior in a particular environment is a mechanism for adaptation. In the absence of any cost to this activity, we might expect agents to choose behaviors that maximize their fitness, an example of directed innovation. This is in contrast to blind mutation, where the probability of becoming a new genotype is independent of the fitness of the new genotypes. Here, we show that under environments punctuated by rapid reversals, a system with both genetic and cultural inheritance should not always maximize fitness through directed innovation. This is because populations highly accurate at selecting the fittest innovations tend to over-fit the environment during its stable phase, to the point that a rapid environmental reversal can cause extinction. A less accurate population, on the other hand, can track long term trends in environmental change, keeping closer to the time-average of the environment. We use both analytical and agent-based models to explore when this mechanism is expected to occur.

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Climatic interpretation of the recently extended Vostok ice records

Cited by 151 publications

References 52 publications

Phase relationships between orbital forcing and the composition of air trapped in Antarctic ice cores

Phase relationships between orbital forcing and the composition of air trapped in Antarctic ice cores

Climate modification by future ice sheet changes and consequences for ice sheet mass balance

Choosing Fitness-Enhancing Innovations Can Be Detrimental under Fluctuating Environments

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