Temperature changes derived from phenological and natural evidences in South Central China from 1850 to 2008
Clim. Past Discuss., 11, 4077-4095, doi:10.5194/cpd-11-4077-2015, 2015
Palaeoclimatic oscillations in the Pliensbachian (Lower Jurassic) of the Asturian Basin (Northern Spain)
Summary: One of challenges is to elucidate if climate during the Jurassic was warmer than present day, with no ice caps. The Pliensbachian Cooling event (Lower Jurassic) has been pointed out as one of the main candidates to have developed ice caps. The Rodiles section of the Asturian Basin (Northern Spain), allows the characterization of several climatic changes of probable global extent.
Clim. Past Discuss., 11, 4039-4076, doi:10.5194/cpd-11-4039-2015, 2015
Pliocene Model Intercomparison (PlioMIP) Phase 2: scientific objectives and experimental design
Clim. Past Discuss., 11, 4003-4038, doi:10.5194/cpd-11-4003-2015, 2015
Variability of sulfate signal in ice-core records based on five replicate cores
Summary: We evaluate the local scale variability of a sulfate profile in a low accumulation site (Dome C, Antarctica), in order to assess the representativeness of one ice-core for volcanic reconstructions. Peaks statistical occurrence as well as depth and flux variability are evaluated from 5 cores. Due to local scale variability, 64 volcanic peaks can be identified through a five cores analysis, while only half of them can be assessed as such from 2 cores. Flux is uncertain by 60 % on average.
Clim. Past Discuss., 11, 3973-4002, doi:10.5194/cpd-11-3973-2015, 2015
Laurentide Ice Sheet basal temperatures at the Last Glacial Cycle as inferred from borehole data
Clim. Past Discuss., 11, 3937-3971, doi:10.5194/cpd-11-3937-2015, 2015
The MIS 5 palaeoenvironmental record in the SE Mediterranean coast of the Iberian Peninsula (Río Antas, Almería, Spain)
Summary: Borehole SRA and the raised beach deposits in the surroundings of the Antas river mouth allowed to reconstruct the Pleistocene palaeoenvironmental evolution of the southern Mediterranean coast of the Iberian Peninsula. The record contains MIS11, MIS6 and MIS5 deposits the latter extensively represented: a sand barrier developed, creating a shallow lagoon with alternating alluvial fan progradation, with evidence of seven scenarios characterized by alternating arid and relatively humid conditions
Clim. Past Discuss., 11, 3897-3936, doi:10.5194/cpd-11-3897-2015, 2015
The influence of non-stationary ENSO teleconnections on reconstructions of paleoclimate using a pseudoproxy framework
Clim. Past Discuss., 11, 3853-3895, doi:10.5194/cpd-11-3853-2015, 2015
The "Dirty Weather" diaries of Reverend Richard Davis: insights about early Colonial-era meteorology and climate variability for Northern New Zealand, 1839–1851
Summary: The meteorological diary of Reverend Richard Davis (1839-1844; 1848-1851) is the earliest continuous daily instrumental weather observation record for New Zealand. It pre-dates James Hector’s meteorological network by more than 20 years, and it contains evidence that temperatures for May-August were on average colder than present day in Northland. Some weather extremes Davis also witnessed may have been more frequent in the mid-1800s relative to the modern era, including frost, ice and snow.
Clim. Past Discuss., 11, 3799-3851, doi:10.5194/cpd-11-3799-2015, 2015
Development of coccolithophore-based transfer functions in the Western Mediterranean Sea: a sea surface salinity reconstruction for the last 15.5 kyr
Summary: Coccolithophore distribution in 88 surface sediment samples in the Atlantic Ocean and Western Mediterranean Sea was mainly influenced by salinity at 10 m depth (SSS). A quantitative coccolithophore-based transfer function was developed and applied to a fossil sediment core to estimate SSS. The good quality of the transfer function and the reliability of the SSS reconstruction were assessed through statistical analyses. Several millennial and centennial SSS changes are identified and discussed.
Clim. Past Discuss., 11, 3759-3798, doi:10.5194/cpd-11-3759-2015, 2015
Multi-time scale data assimilation for atmosphere–ocean state estimates
Summary: We present a novel data assimilation algorithm that incorporates proxy data at arbitrary time scales. Within a synthetic-test framework, we find that atmosphere-ocean states are most skilfully reconstructed by incorporating proxies across multiple time scales compared to using them at short or long time scales alone. Additionally, reconstructions that incorporate long time-scale proxies improve the low-frequency components of the reconstructions relative to using only high-resolution proxies.
Clim. Past Discuss., 11, 3729-3757, doi:10.5194/cpd-11-3729-2015, 2015
A Late Pleistocene sea level stack
Summary: This study presents an average of seven Late Pleistocene sea level records, which improves the signal-to-noise ratio for estimates of sea level change during glacial cycles of the past 800,000 years.
Clim. Past Discuss., 11, 3699-3728, doi:10.5194/cpd-11-3699-2015, 2015
Palaeoceanographic changes in Hornsund Fjord (Spitsbergen, Svalbard) over the last millennium: new insights from ancient DNA
Summary: The presented study focuses on the last millennium of the palaeoclimatic history of Svalbard region. The investigation was based on classical paleoceanographic proxies, strengthened by the analysis of ancient foraminiferal DNA in down-core sediment samples. This study is the first attempt to implement the aDNA record in the paleoenvironmental reconstruction. The aDNA data revealed even small environmetal changes, that were not evidenced in the sedimentological and micropaleontological record.
Clim. Past Discuss., 11, 3665-3698, doi:10.5194/cpd-11-3665-2015, 2015
Hydroclimatic variability in the Levant during the early last glacial (∼ 117–75 ka) derived from micro-facies analyses of deep Dead Sea sediments
Summary: Micro-facies changes and elemental variations in deep Dead Sea sediments are used to reconstruct relative lake level changes for the early last glacial period. The results indicate a close link of hydroclimatic variability in the Levant to North Atlantic-Mediterranean climates during the time of the build-up of Northern Hemisphere ice shields. First petrographic analyses of gravels in the deep core question the recent hypothesis of a Dead Sea dry-down at the end of the last interglacial.
Clim. Past Discuss., 11, 3625-3663, doi:10.5194/cpd-11-3625-2015, 2015
Impact of the oceanic geothermal heat flux on a glacial ocean state
Summary: We investigate the impact of the ocean geothermal heating (OGH) on a glacial ocean state using numerical simulations. We found that the OGH is a significant forcing of the abyssal ocean and thermohaline circulation. Applying the OGH warms the Antarctic Bottom Water by ~0.4°C and strengthens the deep circulation by 15% to 30%. The geothermally heated waters are advected from the Indo-Pacific to the North Atlantic basin, indirectly favouring the deep convection in the North Atlantic.
Clim. Past Discuss., 11, 3597-3624, doi:10.5194/cpd-11-3597-2015, 2015
Relationship between climate change and wars between nomadic and farming groups from the Western Han Dynasty to the Tang Dynasty period
Summary: In ancient China, the change in regional agriculture and animal husbandry productivity caused by climate change led to either wars or peaceful relations between nomadic and farming groups. Through the analysis, to explore the relationship between climate change and wars between nomadic and farming groups.
Clim. Past Discuss., 11, 3567-3595, doi:10.5194/cpd-11-3567-2015, 2015
Climate variability and human impact on the environment in South America during the last 2000 years: synthesis and perspectives
Summary: This paper serves as a guide to high-quality pollen records in South America that capture environmental variability during the last two millennia. We identify the pollen records suitable for climate modelling and discuss their sensitivity to the spatial signature of climate modes. Furthermore, evidence for human land use in pollen records is useful for archaeological hypothesis testing and important in distinguishing natural from anthropogenically driven vegetation change.
Clim. Past Discuss., 11, 3475-3565, doi:10.5194/cpd-11-3475-2015, 2015
The WAIS Divide deep ice core WD2014 chronology – Part 2: Annual-layer counting (0–31 ka BP)
Summary: Here we present a chronology (WD2014) for the upper part (0-2850m, 31.2 ka BP) of the West Antarctic Ice Sheet (WAIS)-Divide ice core which is based on layer counting of distinctive annual cycles preserved in the elemental, chemical and electrical conductivity records. We validated the chronology by comparing to independent high-accuracy, absolutely dated chronologies. Given its demonstrated high accuracy, WD2014 can become a reference chronology for the Southern Hemisphere.
Clim. Past Discuss., 11, 3425-3474, doi:10.5194/cpd-11-3425-2015, 2015
The influence of tropical volcanic eruptions on the climate of South America during the last millennium
Summary: Volcanic forcing is the most important source of forced variability during the pre-industrial component of the Last Millennium (~850-1850 C.E) and is important during the last century. Here, we focus on the climate impact over South America in a study that is largely model-based. Emphasis is given to temperature, precipitation, and oxygen isotope variability (allowing for potential contact made with paleoclimate-based observations)
Clim. Past Discuss., 11, 3375-3424, doi:10.5194/cpd-11-3375-2015, 2015
Abrupt climate variability of eastern Anatolia vegetation during the last glacial
Clim. Past Discuss., 11, 3341-3373, doi:10.5194/cpd-11-3341-2015, 2015
Insights into the early Eocene hydrological cycle from an ensemble of atmosphere–ocean GCM simulations
Clim. Past Discuss., 11, 3277-3339, doi:10.5194/cpd-11-3277-2015, 2015
Paleoclimate reconstruction in the Levant region from the petrography and the geochemistry of a MIS 5 stalagmite from the Kanaan Cave, Lebanon
Summary: The Levant is a key area to study palaeoclimatic responses over G-IG cycles. A precisely dated MIS 5 stalagmite (129–84 ka) from the Kanaan Cave, Lebanon with growth rate and isotopic records variations indicate a warm humid phase at the last interglacial (~129-125 ka). A shift in δ18O values (125-122 ka) is driven by the source effect of the East Med during Sapropel S5. Low growth rates and high δ18O- δ13C values (~122-84 ka) mark the onset of glacial inception and transition to drier phase.
Clim. Past Discuss., 11, 3241-3275, doi:10.5194/cpd-11-3241-2015, 2015
Terrigeneous material supply to the Peruvian central continental shelf (Pisco 14° S) during the last 1100 yr: paleoclimatic implications
Summary: Comparison between records reveals a coherent match between the meridional displacement of the ITCZ-SPSH system and the regional fluvial and aeolian terrigenous input variability. The aeolian input intensity and the anoxic conditions recorded by marine sediments showed a close link that suggests a mechanism associated with SPSH displacement. Changes in sediment discharge to the continental shelf are linked to the southward displacement of the ITCZ-SPSH.
Clim. Past Discuss., 11, 3211-3239, doi:10.5194/cpd-11-3211-2015, 2015
Holocene climate variability in the North-Western Mediterranean Sea (Gulf of Lions)
Clim. Past Discuss., 11, 3187-3209, doi:10.5194/cpd-11-3187-2015, 2015
Revisiting carbonate chemistry controls on planktic foraminifera Mg / Ca: implications for sea surface temperature and hydrology shifts over the Paleocene–Eocene Thermal Maximum and Eocene–Oligocene Transition
Summary: We show that seawater pH exerts a substantial control on planktic foraminifera Mg/Ca, a widely applied palaeothermometer. As a result, temperature reconstructions based on this proxy are likely inaccurate over climatic events associated with a significant change in pH. We examine the implications of our findings for hydrological and temperature shifts over the Paleocene-Eocene Thermal Maximum, and for the degree of surface ocean precursor cooling before the Eocene-Oligocene Transition.
Clim. Past Discuss., 11, 3143-3185, doi:10.5194/cpd-11-3143-2015, 2015
A tree-ring perspective on temporal changes in the frequency and intensity of hydroclimatic extremes in the territory of the Czech Republic since 761 AD
Summary: A new dataset of 3194 oak (Quercus spp.) ring width samples collected across the Czech Republic and covering the past 1250 years was analysed. The temporal distribution of negative and positive TRW extremes occurring is regular with no indication of clustering. Negative TRW extremes coincided with above-average March-May and June-August temperature means and below-average precipitation totals. Positive extremes coincided with higher summer precipitation, while temperatures were mostly normal.
Clim. Past Discuss., 11, 3109-3142, doi:10.5194/cpd-11-3109-2015, 2015
Intra-interglacial climate variability from Marine Isotope Stage 15 to the Holocene
Summary: A set of 13 interglacial time slice experiments was carried out using CCSM3-DGVM model to study global climate variability between and within the Quaternary interglaciations of MIS 1, 5, 11, 13, and 15. The different effects of obliquity, precession and greenhouse gas forcing on global surface temperature and precipitation fields are highlighted. Particularly, we found a significant role of meridional insolation-gradient forcing by obliquity variations in forcing the West African monsoon.
Clim. Past Discuss., 11, 3071-3107, doi:10.5194/cpd-11-3071-2015, 2015
On the state-dependency of the equilibrium climate sensitivity during the last 5 million years
Summary: We find that the specific equilibrium climate sensitivity caused by radiative forcing of CO2 and land ice albedo is state-dependent for the last 2.1Myr (most of the Pleistocene). Its value is during intermediate glaciated climates and interglacial periods about 45% larger than during Pleistocene full glacial conditions. The state-dependency is mainly caused by a latitudinal dependency in ice sheet area changes. Firm conclusions for the Pliocene are due to uncertainties in CO2 not yet possible.
Clim. Past Discuss., 11, 3019-3069, doi:10.5194/cpd-11-3019-2015, 2015
Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the Southwest Pacific
Clim. Past Discuss., 11, 2977-3018, doi:10.5194/cpd-11-2977-2015, 2015
Synchronizing the Greenland ice core and radiocarbon timescales over the Holocene – Bayesian wiggle-matching of cosmogenic radionuclide records
Summary: Here we employ common variations in tree-ring 14C and Greenland ice core 10Be records to synchronize the Greenland ice core and the radiocarbon timescale over the Holocene. We propose a transfer function between both timescales that allows continuous comparisons between radiocarbon dated and ice core climate records at unprecedented chronological precision. We show that absolute ice core layer counting uncertainties have likely been underestimated for large parts of the Holocene.
Clim. Past Discuss., 11, 2933-2975, doi:10.5194/cpd-11-2933-2015, 2015
A massive input of coarse-grained siliciclastics in the Pyrenean Basin during the PETM: the missing ingredient of a coeval abrupt change in hydrological regime
Summary: An abrupt increase in seasonal precipitation during the PETM in the Pyrenean Gulf had earlier been proposed, based on the occurrence of extensive fine-grained siliciclastic deposits. This paper provides evidence that coarse-grained siliciclastics were also delivered, indicative of episodes of intense rainy intervals in an otherwise semiarid PETM climate. Further, evidence is presented that PETM kaolinites were most likely resedimented from Cretaceous lateritic profiles developed in the basement
Clim. Past Discuss., 11, 2889-2931, doi:10.5194/cpd-11-2889-2015, 2015
Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?
Summary: The impact of Neo-Tethys closure on early Cenozoic warming has been tested. First, the volume of subducted sediments and the amount of CO2 emitted along the northern Tethys margin has been calculated. Second, corresponding pCO2 have been tested using the GEOCLIM model. Despite high CO2 production, maximum pCO2 values (750 ppm) do not reach values inferred from proxies. Other cited sources of excess CO2 such as the NAIP are also below fluxes required by GEOCLIM to fit with proxy data.
Clim. Past Discuss., 11, 2847-2888, doi:10.5194/cpd-11-2847-2015, 2015
Terrestrial responses of low-latitude Asia to the Eocene–Oligocene climate transition revealed by integrated chronostratigraphy
Summary: An integrated litho-, bio-, cyclo-, and magnetostratigraphy constrain the onset of the depositional environmental change from a lacustrine to a deltaic environment in low latitude China at 33.77±0.04 Ma. This change coincides with the global cooling during the Eocene-Oligocene transition (EOT) and represents terrestrial responses of low latitude Asia to the EOT. The greatly refined chronology permits detailed examination of the Late Paleogene climate change in Asia.
Clim. Past Discuss., 11, 2811-2845, doi:10.5194/cpd-11-2811-2015, 2015
Inferring climate variability from nonlinear proxies: application to paleo-ENSO studies
Summary: Ignoring nonlinearity in paleoclimate records (e.g. continental runoff proxies) runs the risk of severely overstating changes in climate variability. Even with the correct model and parameters, some information is irretrievably lost by such proxies. However, we find that a simple empirical transform can do much to improve the situation, and makes them amenable to classical analyses. Doing so on two paleo-ENSO records markedly changes some of the quantitative inferences made from such records.
Clim. Past Discuss., 11, 2763-2809, doi:10.5194/cpd-11-2763-2015, 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
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
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
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