Evidence of a prolonged drought ca. 4200 yr BP correlated with prehistoric settlement abandonment from the Gueldaman GLD1 Cave, N-Algeria
Clim. Past Discuss., 11, 2729-2762, doi:10.5194/cpd-11-2729-2015, 2015
Significant recent warming over the northern Tibetan Plateau from ice core δ18O records
Summary: This paper presents the δ18O result of an ice core drilled to bedrock from Mt. Zangser Kangri (ZK), a remote area on the northern Tibetan Plateau (TP). Combining the ZK δ18O series with those from three other ice cores, we reconstructed the regional temperature history in 1951-2008 for the northern TP. The reconstruction captured the continuous rapid warming since 1970, even during global warming hiatus period. It implied that temperature change could have behaved differently at high elevations.
Clim. Past Discuss., 11, 2701-2728, doi:10.5194/cpd-11-2701-2015, 2015
Palaeo plant diversity in subtropical Africa – ecological assessment of a conceptual model of climate–vegetation interaction
Clim. Past Discuss., 11, 2665-2700, doi:10.5194/cpd-11-2665-2015, 2015
Atlantic Multidecadal Oscillation (AMO) forcing on the late Holocene Cauca paleolake dynamics, northern Andes of Colombia
Summary: The San Nicolás laminated sediments of the Cauca paleolake in the northern Andes were deposited in a ria lake environment at 3750-350 yr BP. Wavelet analysis of the San Nicolás-1 core evidences a 70 yr Atlantic Multidecadal Oscillation (AMO) periodicity, analogous to the Cariaco Basin. This supports a correlation between enhanced precipitation and ENSO variability with a positive AMO phase during the 2000-1500 yr BP interval. Increased precipitation occurred ca. 3000 yr BP.
Clim. Past Discuss., 11, 2649-2664, doi:10.5194/cpd-11-2649-2015, 2015
The pCO2 estimates of the late Eocene in South China based on stomatal density of Nageia Gaertner leaves
Clim. Past Discuss., 11, 2615-2647, doi:10.5194/cpd-11-2615-2015, 2015
Gridded climate data from 5 GCMs of the Last Glacial Maximum downscaled to 30 arc s for Europe
Summary: Global climate model output for the Last Glacial Maximum (LGM) is downscaled to a very high resolution using the change factor method. We develop two new methods to extend current baseline climate to the LGM coastline so that the final data cover all terrestrial area at LGM. Results are gridded data for temperature, precipitation and 19 bioclimatic variables which are often used in studies on climate change impact on biological diversity, glacial refugia or migration during Holocene warming.
Clim. Past Discuss., 11, 2585-2613, doi:10.5194/cpd-11-2585-2015, 2015
Constraints on ocean circulation at the Paleocene–Eocene Thermal Maximum from neodymium isotopes
Summary: The Paleocene-Eocene Thermal Maximum (PETM) was a brief period when the Earth was in an extreme greenhouse state. We use neodymium isotopes to suggest that during this time deep ocean circulation was distinct in each basin (North, South Atlanic, Southern, Pacific) with little exchange between. Moreover, the Pacific data shows the most variability, suggesting this was a critical region possibly involved in both PETM triggering and remediation.
Clim. Past Discuss., 11, 2557-2583, doi:10.5194/cpd-11-2557-2015, 2015
Continental-scale temperature variability in PMIP3 simulations and PAGES 2k regional temperature reconstructions over the past millennium
Summary: A comparison of model simulations and reconstructions at the continental-scale over the past millennium indicates that models are in relatively good agreement with temperature reconstructions for Northern Hemisphere regions, particularly in the Arctic. This is likely due to the relatively large amplitude of the externally forced response across northern and high latitudes regions. Conversely, models disagree strongly with the reconstructions in the Southern Hemisphere.
Clim. Past Discuss., 11, 2483-2555, doi:10.5194/cpd-11-2483-2015, 2015
Effects of eustatic sea-level change, ocean dynamics, and iron fertilization on atmospheric pCO2 and seawater composition over the last 130 000 years
Summary: An earth system model was set up and applied to evaluate the effects of sea-level change, ocean dynamics, and iron fertilization on seawater composition and atmospheric pCO2 over the last glacial cycle. The model results strongly suggest that global sea-level change contributed significantly to the slow glacial decline in atmospheric pCO2 and the gradual pCO2 increase over the Holocene whereas the rapid deglacial pCO2 rise was induced by fast changes in ocean dynamics and iron fertilization.
Clim. Past Discuss., 11, 2405-2481, doi:10.5194/cpd-11-2405-2015, 2015
Palaeo sea-level and ice-sheet databases: problems, strategies and perspectives
Summary: This review/position paper addresses problems in creating new interdisciplinary databases for palaeo-climatological sea-level and ice-sheet data and gives an overview on new advances to tackle them. The focus therein is to define and explain strategies and highlight their importance to allow further progress in these fields. It also offers important insights into the general problematic to design competitive databases, which are also applicable to other communities within the palaeo environment.
Clim. Past Discuss., 11, 2389-2404, doi:10.5194/cpd-11-2389-2015, 2015
Spatial and temporal oxygen isotope variability in northern Greenland – implications for a new climate record over the past millennium
Summary: will be provided later
Clim. Past Discuss., 11, 2341-2388, doi:10.5194/cpd-11-2341-2015, 2015
Quantifying molecular oxygen isotope variations during a Heinrich Stadial
Clim. Past Discuss., 11, 2281-2339, doi:10.5194/cpd-11-2281-2015, 2015
Climate–vegetation modelling and fossil plant data suggest low atmospheric CO2 in the late Miocene
Summary: We simulated Late Miocene (11- 7 Million years ago) vegetation using two plausible CO2 concentrations, 280ppm CO2 and 450ppm CO2. We compared the simulated vegetation to existing plant fossil data for the whole Northern Hemisphere. Our results suggest that during the Late Miocene the CO2 levels have been relatively low, or that other factors that are not included in the models maintained the seasonal temperate forests and open vegetation.
Clim. Past Discuss., 11, 2239-2279, doi:10.5194/cpd-11-2239-2015, 2015
Orbital control on late Miocene climate and the North African monsoon: insight from an ensemble of sub-precessional simulations
Summary: This paper investigates the climatic response to orbital forcing through the analysis of an ensemble of simulations covering a late Miocene precession cycle. Including orbital variability in our model-data comparison reduces the mismatch between the proxy record and model output. Our results indicate that ignoring orbital variability could lead to miscorrelations in proxy reconstructions. The North African summer monsoon's sensitivity is high to orbits, moderate to paleogeography and low to CO2.
Clim. Past Discuss., 11, 2181-2237, doi:10.5194/cpd-11-2181-2015, 2015
A 250 year periodicity in Southern Hemisphere westerly winds over the last 2600 years
Summary: Southern Hemisphere westerly airflow is considered a major driver of Southern Ocean and global climate. Observational records, however, are limited. Here we present a new record from the Falkland Islands by exploiting South America pollen to reconstruct westerly airflow. We find enhanced airflow 2000-1000cal. yr BP, associated with increased burning, and a 250-year periodicity, suggesting solar forcing. Our results have important implications for understanding late Holocene global climate.
Clim. Past Discuss., 11, 2159-2180, doi:10.5194/cpd-11-2159-2015, 2015
Eastern Andean environmental and climate synthesis for the last 2000 years BP from terrestrial pollen and charcoal records of Patagonia
Clim. Past Discuss., 11, 2121-2157, doi:10.5194/cpd-11-2121-2015, 2015
Stratification of surface waters during the last glacial millennial climatic events: a key factor in subsurface and deep water mass dynamics
Summary: This study documents the hydrological variations recorded at different depths of the water column SW off Faeroe during the last glacial abrupt climatic events (Heinrich events and Dansgaard-Oeschger cycles). Our combined multiproxy and high resolution approach allows us to evidence that: 1) Greenland and Heinrich stadials were characterized by a strong stratification of surface waters, 2) this surface stratification seems to have played a key role in the dynamics of the underlying water masses.
Clim. Past Discuss., 11, 2077-2119, doi:10.5194/cpd-11-2077-2015, 2015
Environmental and climatic history in the NW Argentine Andes (24° S) over the last 2100 years inferred from a high-altitude peatland record
Summary: Cushion peatlands are versatile climate archives for the study of past environmental changes. We present the environmental history for the last 2100 years of Cerro Tuzgle peatland, which is located in the NW Argentine Puna. The results reflect prominent late Holocene climate anomalies and provide evidence that Northern Hemisphere climate oscillations were extensive. Volcanic forcing at the beginning of the 19th century seems to have had an impact on climatic settings in the central Andes.
Clim. Past Discuss., 11, 2037-2076, doi:10.5194/cpd-11-2037-2015, 2015
Glacier response to North Atlantic climate variability during the Holocene
Clim. Past Discuss., 11, 2009-2036, doi:10.5194/cpd-11-2009-2015, 2015
Comment on "Radiative forcings for 28 potential Archean greenhouse gases" by Byrne and Goldblatt (2014)
Summary: In the article Clim Past 10, 1779 (2014), the HITRAN2012 database was employed to evaluate the radiative forcing of 28 Archean gases. The authors claimed that for NO2, H2O2, C2H4, CH3OH, and CH3Br there are severe disagreements between cross sections generated from the HITRAN line-by-line data and those of the PNNL experimental database. In this work we show that the differences are not nearly at the scale suggested by the authors, and their conclusions about these gases and HO2 are not correct.
Clim. Past Discuss., 11, 1985-2007, doi:10.5194/cpd-11-1985-2015, 2015
Carbon cycle dynamics during recent interglacials
Clim. Past Discuss., 11, 1945-1983, doi:10.5194/cpd-11-1945-2015, 2015
Miocene–Pliocene stepwise intensification of the Benguela upwelling over the Walvis Ridge off Namibia
Clim. Past Discuss., 11, 1913-1943, doi:10.5194/cpd-11-1913-2015, 2015
Climatic variability and human impact during the last 2000 years in western Mesoamerica: evidences of late Classic and Little Ice Age drought events
Summary: We present results from western Mexico, where very few paleoclimatic research sites exist. The record has good chronological resolution (ca. 20yr) and clear climatic trends during the last 2ka. The most important signals are: 1. dry conditions during the late Classic (AD 500 to 1000), specially from AD 600 to 800 and 2. low lake levels during the LIA, in two phases that follow Spörer and Maunder solar minima. Dryer conditions are realted wtih a lower intentisty of the North American Monsoon.
Clim. Past Discuss., 11, 1887-1911, doi:10.5194/cpd-11-1887-2015, 2015
Carbon isotope excursions in paleosol carbonate marking five early Eocene hyperthermals in the Bighorn Basin, Wyoming
Summary: Ancient greenhouse warming episodes are studied in river floodplain sediments in the western interior of the USA. Paleohydrological changes reveal to be opposite for four smaller warming episodes than for the largest, most-studied event. Carbon cycle tracers are used to unravel whether this largest event was a similar event but scaled to the smaller ones, or if this event was distinct not only in size but also in carbon sourcing, for which the current work cannot come with a definitive solution.
Clim. Past Discuss., 11, 1857-1885, doi:10.5194/cpd-11-1857-2015, 2015
Multi-century lake area changes in the Andean high-elevation ecosystems of the Southern Altiplano
Clim. Past Discuss., 11, 1821-1855, doi:10.5194/cpd-11-1821-2015, 2015
Frequency, magnitude and character of hyperthermal events at the onset of the Early Eocene Climatic Optimum
Summary: Several episodes of global warming took place during greenhouse conditions in the early Eocene and are recorded in deep-sea sediments. The stable carbon and oxygen isotope records are used to investigate the magnitude of six of these events describing their effects on the global carbon cycle and the associated temperature response. Findings indicate that these events share a common nature and hint to the presence of multiple sources of carbon release.
Clim. Past Discuss., 11, 1795-1820, doi:10.5194/cpd-11-1795-2015, 2015
A collection of sub-daily pressure and temperature observations for the early instrumental period with a focus on the "year without a summer" 1816
Summary: A dataset of instrumental pressure and temperature observations for the early instrumental period (before ca. 1850) is described. This is the result of a digitisation effort involving the period immediately after the eruption of Mount Tambora in 1815, combined with the collection of already available sub-daily time series. The highest data availability is therefore for the years 1815 to 1817. An analysis of pressure variability and of case studies in Europe is performed for that period.
Clim. Past Discuss., 11, 1741-1794, doi:10.5194/cpd-11-1741-2015, 2015
Rapid millennial-scale vegetation changes in the tropical Andes
Summary: We compare eight pollen records reflecting environmental change in the tropical Andes over the past 50,000 years. We identify rapid responses of the tropical vegetation to millennial-scale climate variability, and relate differences between sites to moisture sources and site sensitivity.
Clim. Past Discuss., 11, 1701-1739, doi:10.5194/cpd-11-1701-2015, 2015
Astronomical calibration of the geological timescale: closing the middle Eocene gap
Summary: Testing hypotheses for mechanisms and dynamics of past climate change rely on the accuracy of geological dating. Development of a highly accurate geological time scale for the Cenozoic Era has previously been hampered by discrepancies between radio-isotopic and astronomical dating methods, and a stratigraphic gap in the middle Eocene. We close this gap and provide a fundamental advance in establishing a reliable and highly accurate geological time scale for the last 66 million years.
Clim. Past Discuss., 11, 1665-1699, doi:10.5194/cpd-11-1665-2015, 2015
The Eocene–Oligocene transition at ODP Site 1263, Atlantic Ocean: decreases in nannoplankton size and abundance and correlation with benthic foraminiferal assemblages
Summary: Deep-sea sediments at ODP Site 1263 (Walvis Ridge, South Atlantic) show that marine calcifying algae decreased in abundance and size at the Eocene-Oligocene boundary, when the Earth transitioned from a greenhouse to a more glaciated and cooler climate. This decreased the food supply for benthic foraminifer communities. The plankton rapidly responded to fast-changing conditions, such as seasonal nutrient availability, or to threshold-levels in pCO2, cooling and ocean circulation.
Clim. Past Discuss., 11, 1615-1664, doi:10.5194/cpd-11-1615-2015, 2015
Stability of ENSO and its tropical Pacific teleconnections over the Last Millennium
Clim. Past Discuss., 11, 1579-1613, doi:10.5194/cpd-11-1579-2015, 2015
Stability of the vegetation–atmosphere system in the early Eocene climate
Clim. Past Discuss., 11, 1551-1578, doi:10.5194/cpd-11-1551-2015, 2015
Phase relationships between orbital forcing and the composition of air trapped in Antarctic ice cores
Summary: We present new measurements of dO2/N2 and d18Oatm performed on well-conserved ice from EDC between MIS5 and 380-800 ka. We present a multi-proxy comparison over MIS 5 of EDC, Vostok and Dome F. Our results indicate that the dO2/N2 can be influenced by local climatic parameters. Then, combining Vostok and EDC records, we are able to discuss the delay between d18Oatm and precession over the last 800 ka. This delay has varied through time, periods of larger delay are associated with Heinrich events
Clim. Past Discuss., 11, 1437-1477, doi:10.5194/cpd-11-1437-2015, 2015
Parallelisms between sea surface temperature changes in the western tropical Atlantic (Guiana basin) and high latitude climate signals over the last 140 000 years
Summary: The alkenone sea surface temperatures in the Guiana basin show a rapid transmission of the climate variability from arctic-to-tropical latitudes during the last two interglacials (MIS1 and MIS5e) and warm long interstadials (MIS5d-a). In contrast, the abrupt variability of the glacial interval does not follow the North Atlantic climate but it is shaped by precessional changes. This arctic-to-tropical decoupling occurs when the Atlantic meridional overturning circulation is substantially reduced
Clim. Past Discuss., 11, 1143-1175, doi:10.5194/cpd-11-1143-2015, 2015
Early-Holocene warming in Beringia and its mediation by sea-level and vegetation changes
Summary: The ongoing warming of the Arctic is producing changes in vegetation and hydrology, that coupled with rising sea level, could mediate the global changes. We explore this possibility using a regional climate-model simulations of a past interval of warming in Beringia, and found that the regional-scale changes do strongly mediate the responses to global changes, amplifying them in some cases, damping them in others, and, overall, generating considerable spatial heterogeneity in climate change.
Clim. Past Discuss., 11, 873-932, doi:10.5194/cpd-11-873-2015, 2015
Optimal Ranking Regime analysis of TreeFlow dendrohydrological reconstructions
Summary: A new approach to time series analysis - the ORR method- was used to evaluate reconstructed western U.S. streamflow records during 1500-2007. This method shows an interesting pattern of alternating drought and wet periods during the late 16th and 17th centuries, a period with relatively few drought or wet periods during the 18th century, and the and the reappearance of alternating dry and wet periods during the 19th and early 20th centuries.
Clim. Past Discuss., 11, 755-803, doi:10.5194/cpd-11-755-2015, 2015
South-western Africa vegetation responses to atmospheric and oceanic changes during the last climatic cycle
Summary: We present a new pollen-based palaeoclimatic reconstruction covering the period between 190,000 and 24,000 years ago from a marine sediment core located off the Namibian coast. Our work identifies increased dryness during the three warmest periods of the last interglacial involving atmospheric and oceanic reorganizations in southern Africa that are linked to precession minima.
Clim. Past Discuss., 11, 345-376, doi:10.5194/cpd-11-345-2015, 2015