A new approach for modeling Cenozoic oceanic lithium isotope paleo-variations: the key role of climate
Summary: We develop here a new approach that couples the carbon and lithium cycles for reconstructing the Cenozoic Li isotope record. We show that this record does not provide persuasive, unique evidence for Cenozoic change in erosional forcing as it could, alternatively, be consistent with climatic control on soil production rates. The Li storage in continental secondary phases plays a key role, in particular, during the Early Cenozoic.
Clim. Past, 11, 635-645, doi:10.5194/cp-11-635-2015, 2015
High-resolution leaf wax carbon and hydrogen isotopic record of the late Holocene paleoclimate in arid Central Asia
Clim. Past, 11, 619-633, doi:10.5194/cp-11-619-2015, 2015
Interannual climate variability seen in the Pliocene Model Intercomparison Project
Summary: Previously, model ensembles have shown little consensus in the response of the El Niño–Southern Oscillation (ENSO) to imposed forcings – either for the past or future. The recent coordinated experiment on the warm Pliocene (~3 million years ago) shows surprising agreement that there was a robustly weaker ENSO with a shift to lower frequencies. Suggested physical mechanisms cannot explain this coherent signal, and it warrants further investigation.
Clim. Past, 11, 605-618, doi:10.5194/cp-11-605-2015, 2015
Late Weichselian and Holocene palaeoceanography of Storfjordrenna, southern Svalbard
Summary: Storfjordrenna was deglaciated about 13,950 cal yr BP. During the transition from the sub-glacial to glaciomarine setting, Arctic Waters dominated its hydrography. However, the waters were not uniformly cold and experienced several warmer spells. Atlantic Water began to flow onto the shelves off Svalbard and into Storfjorden during the early Holocene, leading to progressive warming and significant glacial melting. A surface-water cooling and freshening occurred in late Holocene.
Clim. Past, 11, 587-603, doi:10.5194/cp-11-587-2015, 2015
The impact of Sahara desertification on Arctic cooling during the Holocene
Clim. Past, 11, 571-586, doi:10.5194/cp-11-571-2015, 2015
Diminished greenhouse warming from Archean methane due to solar absorption lines
Summary: High methane concentrations are thought to have helped sustain warm surface temperatures on the early Earth (~3 billion years ago) when the sun was only 80% as luminous as today. However, radiative transfer calculations with updated spectral data show that methane is a stronger absorber of solar radiation than previously thought. In this paper we show that the increased solar absorption causes a redcution in the warming ability of methane in the Archaean atmosphere.
Clim. Past, 11, 559-570, doi:10.5194/cp-11-559-2015, 2015
Inferring palaeo-accumulation records from ice-core data by an adjoint-based method: application to James Ross Island's ice core
Clim. Past, 11, 547-557, doi:10.5194/cp-11-547-2015, 2015
Technical Note: Probabilistically constraining proxy age–depth models within a Bayesian hierarchical reconstruction model
Summary: We present a Bayesian approach to simultaneously constrain the age models associated with time-uncertain proxies and inferring past climate in space and time. For the sake of exposition, the discussion focuses on annually resolved climate archives, such as varved lakes, corals, and tree rings, with dating by layer counting. Numerical experiments show that updating the probabilities associated with an ensemble of possible age models reduces uncertainty in the inferred climate.
Clim. Past, 11, 533-545, doi:10.5194/cp-11-533-2015, 2015
Evidence for the non-influence of salinity variability on the Porites coral Sr/Ca palaeothermometer
Summary: The influence of salinity on the Porites Sr/Ca palaeothermometer is still poorly documented. We test the salinity effect on Porites Sr/Ca-based SST reconstructions using a large spatial compilation of published Porites data from the Pacific, Indian Ocean, and the Red Sea. We find no evidence of a salinity bias in the Sr/Ca SST proxy at monthly and interannual timescales using two different salinity products. This result is in agreement with laboratory experiments on coral species.
Clim. Past, 11, 523-532, doi:10.5194/cp-11-523-2015, 2015
A high-resolution δ18O record and Mediterranean climate variability
Summary: The key to gaining information on climate over the last millennia is the study of proxy records in ice and sediment cores, trees, etc. We measured the oxygen isotopic ratio in planktonic foraminifera of a high-resolution, well-dated central Mediterranean core. The comparison between the variability detected in this core and that characterizing the Northern Hemisphere allows for local and global (hemispheric) climate variations to be distinguished.
Clim. Past, 11, 509-522, doi:10.5194/cp-11-509-2015, 2015
Freshwater discharge controlled deposition of Cenomanian–Turonian black shales on the NW European epicontinental shelf (Wunstorf, northern Germany)
Summary: Based on the chemistry and microfossils preserved in sediments deposited in a shallow sea, in the current Lower Saxony region (NW Germany), we conclude that changes in Earth’s orbit around the Sun led to enhanced rainfall and organic matter production. The additional supply of organic matter, depleting oxygen upon degradation, and freshwater, inhibiting the mixing of oxygen-rich surface waters with deeper waters, caused the development of oxygen-poor waters about 94 million years ago.
Clim. Past, 11, 495-508, doi:10.5194/cp-11-495-2015, 2015
Early Paleogene variations in the calcite compensation depth: new constraints using old borehole sediments from across Ninetyeast Ridge, central Indian Ocean
Clim. Past, 11, 473-493, doi:10.5194/cp-11-473-2015, 2015
Global climate simulations at 3000-year intervals for the last 21 000 years with the GENMOM coupled atmosphere–ocean model
Clim. Past, 11, 449-471, doi:10.5194/cp-11-449-2015, 2015
Statistical framework for evaluation of climate model simulations by use of climate proxy data from the last millennium – Part 3: Practical considerations, relaxed assumptions, and using tree-ring data to address the amplitude of solar forcing
Summary: Experiments with climate models can help to understand causes of past climate changes. We develop a statistical framework for comparing data from simulation experiments with temperature reconstructions for the last millennium. A combination of several external factors is found to explain a significant part of the observed variations, but our selection of data cannot tell which of two alternative choices of past solar forcing gives the best fit between simulations and reconstructions.
Clim. Past, 11, 425-448, doi:10.5194/cp-11-425-2015, 2015
Using results from the PlioMIP ensemble to investigate the Greenland Ice Sheet during the mid-Pliocene Warm Period
Summary: Climate and ice sheet models are often used to predict the nature of ice sheets in Earth history. It is important to understand whether such predictions are consistent among different models, especially in warm periods of relevance to the future. We use input from 15 different climate models to run one ice sheet model and compare the predictions over Greenland. We find that there are large differences between the predicted ice sheets for the warm Pliocene (c. 3 million years ago).
Clim. Past, 11, 403-424, doi:10.5194/cp-11-403-2015, 2015
Climate variability and ocean fertility during the Aptian Stage
Clim. Past, 11, 383-402, doi:10.5194/cp-11-383-2015, 2015
Ice sheet model dependency of the simulated Greenland Ice Sheet in the mid-Pliocene
Summary: The paper assess the Greenland Ice Sheet’s sensitivity to a warm period in the past, a time when atmospheric CO2 concentrations were comparable to current levels. We quantify ice sheet volume and locations in Greenland and find that the ice sheets are less sensitive to differences in ice sheet model configurations than to changes in imposed climate forcing. We conclude that Pliocene ice was most likely to be limited to highest elevations in eastern and southern Greenland.
Clim. Past, 11, 369-381, doi:10.5194/cp-11-369-2015, 2015
Comparing past accumulation rate reconstructions in East Antarctic ice cores using 10Be, water isotopes and CMIP5-PMIP3 models
Summary: We present a new 10Be record at EDC between 269 and 355ka. Our 10Be-based accumulation rate is in good agreement with the one associated with the EDC3 timescale except for the warm MIS 9.3 optimum. This suggests that temperature reconstruction from water isotopes may be underestimated by 2.4K for the difference between the MIS 9.3 and present day. The CMIP5-PMIP3 models do not quantitatively reproduce changes in precipitation vs. temperature increase during glacial–interglacial transitions.
Clim. Past, 11, 355-367, doi:10.5194/cp-11-355-2015, 2015
East Asian Monsoon controls on the inter-annual variability in precipitation isotope ratio in Japan
Summary: This study demonstrates that the intensity of the East Asian summer and winter monsoon is the primary driver of variations of summer and winter precipitation isotopes in central Japan. Japan lies in the northeast limits of the East Asian monsoon region. Understanding the past monsoon changes in Japan is important for determining whether the isotopic variability recorded in Chinese stalagmite reflects the East Asian summer monsoon intensity or rainfall variability in the Indian summer monsoon.
Clim. Past, 11, 339-353, doi:10.5194/cp-11-339-2015, 2015
Variability of summer humidity during the past 800 years on the eastern Tibetan Plateau inferred from δ18O of tree-ring cellulose
Clim. Past, 11, 327-337, doi:10.5194/cp-11-327-2015, 2015