The sharp decline of East Asian summer monsoon at mid-Holocene indicated by the lake-wetland transition in the Sanjiang Plain, northeastern China
Summary: The results show that the shallow-water lakes have developed in low-lying areas of the plain before 4600 yr BP, corresponding to the Holocene monsoon maximum. Thereafter, the wetlands began to initiate with the extinction of the paleolakes, marking a lake-shrinking stage with the relative dry climate.We suggest the lake-wetland transition at 4600 yr BP indicate a sharp decline of the summer monsoon.
Thermal evolution of the western South Atlantic and the adjacent continent during Termination 1
Summary: Here we show that temperatures in the western South Atlantic increased markedly during the major slowdown event of the Atlantic meridional overturning circulation (AMOC) of the last deglaciation. Over the adjacent continent, however, temperatures followed the rise in atmospheric carbon dioxide, lagging changes in oceanic temperature. Our records corroborate the notion that the long duration of the major slowdown event of the AMOC was fundamental to drive the Earth out of the last glacial.
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, discussion focusses 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.
A two thousand year annual record of snow accumulation rates for Law Dome, East Antarctica
Summary: The Law Dome, East Antarctica snow accumulation record is extended back to -22 AD using a power law vertical strain rate model. The periods 380-442 AD, 727-783 AD and 1970-2009 AD have above average snow accumulation rates, while 663-704 AD, 933-975 AD and 1429-1468 AD were below average. The calculated snow accumulation rates show good correlation with atmospheric reanalysis estimates, and significant spatial correlation over a wide expanse of East Antarctica.
Reconciling reconstructed and simulated features of the winter Pacific–North-American pattern in the early 19th century
Summary: A discrepancy exists between reconstructed and simulated Pacific North American pattern (PNA) features during the early 19th century. Pseudo-reconstructions demonstrate that the available PNA reconstruction is potentially skillful but also potentially affected by a number of sources of uncertainty and deficiencies especially at multidecadal and centennial timescales. Simulations and reconstructions can be reconciled by attributing the reconstructed PNA features to internal variability.
Twelve thousand years of dust: the Holocene global dust cycle constrained by natural archives
Summary: We propose an innovative framework to organize paleodust records, formalized in a publicly accessible database, and discuss the emerging properties of the global dust cycle during the Holocene by integrating our analysis with simulations performed with the Community Earth System Model. We show how the size distribution of dust is intrinsically related to the dust mass accumulation rates, and that only considering a consistent size range allows for a consistent analysis of the global dust cycle.
S. Albani, N. M. Mahowald, G. Winckler, R. F. Anderson, L. I. Bradtmiller, B. Delmonte, R. François, M. Goman, N. G. Heavens, P. P. Hesse, S. A. Hovan, K. E. Kohfeld, H. Lu, V. Maggi, J. A. Mason, P. A. Mayewski, D. McGee, X. Miao, B. L. Otto-Bliesner, A. T. Perry, A. Pourmand, H. M. Roberts, N. Rosenbloom, T. Stevens, and J. Sun Clim. Past Discuss., 10, 4277-4363, 2014 AbstractDiscussion Paper (PDF, 6250 KB)Supplement (8823 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for CP
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 Archean atmosphere.
Carbon isotope (δ13C) excursions suggest times of major methane release during the last 14 ka in Fram Strait, the deep-water gateway to the Arctic
Summary: A sediment core collected from a pockmark field on the Vestnesa Ridge (~80N) in the Fram Strait is presented. Our results show an undisturbed sedimentary record for the last 14 ka BP and negative carbon isotope excursions (CIEs) during the Bølling-Allerød interstadials and during the early Holocene. Both CIEs relate to periods of ocean warming, sea level rise and increased concentrations of methane (CH4) in the atmosphere, suggesting an apparent correlation with warm climatic events.
A 500 year seasonally resolved δ18O and δ13C, layer thickness and calcite fabric record from a speleothem deposited in equilibrium of the Han-sur-Lesse cave, Belgium
M. Van Rampelbergh, S. Verheyden, M. Allan, Y. Quinif, H. Cheng, L. Edwards, E. Keppens, and P. Claeys Clim. Past Discuss., 10, 4149-4190, 2014 AbstractDiscussion Paper (PDF, 4049 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for CP
22 Oct 2014
A high-resolution δ18O record and Mediterranean climate variability
Northern Hemisphere control of deglacial vegetation changes in the Rufiji uplands (Tanzania)
I. Bouimetarhan, L. Dupont, H. Kuhlmann, J. Pätzold, M. Prange, E. Schefuß, and K. Zonneveld Clim. Past Discuss., 10, 3931-3964, 2014 AbstractDiscussion Paper (PDF, 882 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for CP
30 Sep 2014
Spatial climate dynamics in the Iberian Peninsula since 15 000 Yr BP
P. Tarroso, J. Carrión, M. Dorado-Valiño, P. Queiroz, L. Santos, A. Valdeolmillos-Rodríguez, P. Célio Alves, J. C. Brito, and R. Cheddadi Clim. Past Discuss., 10, 3901-3930, 2014 AbstractDiscussion Paper (PDF, 1492 KB)Supplement (1419 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for CP
26 Sep 2014
Technical Note: How accurate can stalagmite formation temperatures be determined using vapour bubble radius measurements in fluid inclusions?
F. Spadin, D. Marti, R. Hidalgo-Staub, Y. Krüger, J. Rička, D. Fleitmann, and M. Frenz Clim. Past Discuss., 10, 3689-3713, 2014 AbstractDiscussion Paper (PDF, 2688 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for CP
09 Sep 2014
Variability of summer humidity during the past 800 years on the eastern Tibetan Plateau inferred from δ18O of tree-ring cellulose