Holocene Climate History Research Articles

Holocene climatic and environmental changes inferred from midge records (Diptera: Chironomidae, Chaoboridae, Ceratopogonidae) at Lake Berkut, southern Kola Peninsula, Russia

A radiocarbon-dated sediment sequence from Lake Berkut in the southern part of the Kola Peninsula, northwest Russia, was investigated by means of midge analysis in order to reconstruct the Holocene climatic and environmental history of the region. Past mean July air temperatures at the study site and hypolimnetic oxygen contents of the lake water were inferred from chironomid-based transfer functions. The early Holocene ( c. 10 100-8400 cal. yr BP) is characterized by summer temperatures and hypolimnetic oxygen concentrations broadly similar to present-day conditions. The midge records give evidence of a lake-level fall at c. 7000 cal. yr BP, resulting in weakened thermal stratification of the lake water, and improvement of the hypolimnetic oxygen conditions. After c. 4000 cal. yr BP midge assemblages suggest a lake-level rise related to increased effective moisture. A secondary mid-Holocene climatic optimum with inferred mean July air temperatures of c. 12.1° C was recorded between 6000 and 4400 cal. yr BP, followed by minimum values (c. 11.3°C) between 3500 and 1500 cal. yr BP, accompanied by the onset of natural acidification of the lake. The late-Holocene midge assemblages suggest weakly acidic conditions, low hypolimnetic oxygen contents and a general warming trend during the last c. 1500 years, although paludification and natural acidification may have influenced the temperature reconstruction at this stage. However, the modern chironomid-inferred mean July air temperature (12.5°C) is consistent with meteorological data from a nearby station. In general, the midge records reflect relatively warm and moist conditions at Lake Berkut before c. 7000 cal. yr BP, a relatively warm and dry climate at c. 7000-4000 cal. yr BP, and a shift to cooler and wetter climatic conditions in the region after c. 4000 cal. yr BP.

Impact of climate change on soil erosion, runoff, and wheat productivity in central Oklahoma

The potential for global climate changes to increase the risk of soil erosion is clear, but the actual damage is not. The objectives of this study were to evaluate the potential impacts of climate change on soil erosion, surface runoff, and wheat productivity in central Oklahoma. Monthly projections were used from the Hadley Centre's general circulation model, HadCM3, using scenarios A2a, B2a, and GGa1 for the periods of 1950–1999 and 2070–2099. Projected changes in monthly precipitation and temperature distributions between the two periods were incorporated into daily weather series by means of a stochastic weather generator (CLIGEN) with its input parameters adjusted to each scenario. The Water Erosion Prediction Project (WEPP) model was run for four climate scenarios including a recent historical climate and three tillage systems (conventional tillage, conservation tillage, and no-till). HadCM3-projected mean annual precipitation during 2070–2099 at El Reno, Oklahoma decreased by 13.6%, 7.2%, and 6.2% for A2a, B2a, and GGa1, respectively; and mean annual temperature increased by 5.7, 4.0, and 4.7 °C, respectively. Predicted average annual soil loss in the tillage systems other than no-till, compared with historical climate (1950–1999), increased by 18–30% for A2a, remained similar for B2a, and increased by 67–82% for GGa1. Predicted soil loss in no-till did not increase in the three scenarios. Predicted mean annual runoff in all three tillage systems increased by 16–25% for A2a, remained similar for B2a, and increased by 6–19% for GGa1. The greater increases in soil loss and runoff in GGa1 were attributed to greater variability in monthly precipitation as projected by HadCM3. The increased variability led to increased frequency of large storms. Small changes in wheat yield, which ranged from a 5% decrease in B2a to a 5% increase in GGa1, were because the adverse effects of the temperature increase on winter wheat growth were largely offset by CO 2 rise as well as the bulky decrease in precipitation occurred outside the growing season. The overall results indicate that no-till and conservation tillage systems will be effective in combating soil erosion under projected climates in central Oklahoma.

Late glacial to Holocene climate and sedimentation history in the NW Black Sea

Gravity cores from the continental slope in the northwestern Black Sea were studied using high-resolution stable isotope, grain size and XRF-scanning data. The measurements provide a 30 000 years AMS 14C-dated record of variations in the hydrological regime of the Black Sea and give insight into changing paleoenvironments in the surrounding areas. Stable climatic conditions during the Last Glacial Maximum were followed by a series of meltwater pulses most likely originating from the Scandinavian ice sheet between 18 000 and 15 500 yr BP. 1 1 All dates are calibrated to calendar years B.P. (yr BP). This meltwater input rose the level of the Caspian Sea to a point that Caspian water could spill into the Black Sea via the Manych-depression north of the Caucasian mountains. High-frequency oscillations in the XRF-data during this period suggest a probable link to the arctic climate regime. Later, during the Bølling/Allerød and the early Holocene, prevailing high temperatures led to authigenic calcite precipitation through increased phytoplankton activity, interrupted by the Younger Dryas and the “8200 yr BP cold event” with dominant clastic sedimentation.

Records of Holocene Environmental Changes in Terrestrial Sedimentary Deposits on King George Island, Antarctica; A Critical Review

In this study we discuss some problems that emerged from paleolimnological and paleontological investigations of terrestrial Holocene ecosystems on King George Island (South Shetland Islands) conducted by an Argentine-Polish research group. Biological and geochemical markers commonly used in standard analytical procedures are considered insufficient in tracing overlapping records of past environmental changes preserved in peat banks, lake sediments and ornithogenic remnants. Records that might be explained by predictable natural events (related to glacio-isostatic uplift of land), roughly predictable events (ecological succession), or unpredictable events (volcanic eruptions or accidental destruction of aquatic moss) may overlap or interfinger one with another providing that signals of regional and/or global climatic changes, are hardly identifiable. A more sophisticated and more selective methods are recommended to do discrimination between records of local and regional/golbal processes in studies on Holocene climatic history of the South Shetland Islands.

Impacts of land use and climate change on regional net primary productivity

Combined with recent historical climate data and two periods of land use data sets from remote sensing data, we test the net primary productivity (NPP) data sets in North China modelled by the satellite data-driven Global Production Efficiency Model (GLO-PEM) for detecting the widespread spatial and temporal characteristics of the impacts of climate and land use change on the regional NPP. Our results show that over the past 20 years, the mean annual temperature in the study region has remarkably increased by more than 0.064 °C, but over the same period, there has been a 1.49 mm decrease in annual precipitation and decrease in NPP by an annual rate of 6.9 TgC. The NPP changes in the study region were greatly affected by the average temperature and precipitation by ten-day periods as well as the seasonal temperature and precipitation in the study region. The correlation between seasonal NPP and seasonal precipitation and temperature is highly consistent with land cover spatially, and the correlation coefficient changes with the changes of vegetation types. The analysis reveals that the related areas in land use change only take up 5.45% of the whole studied region, so the climate changes dominate the impacts on the NPP in the whole study region (90% of the total). However, land use plays an absolute dominative role in areas with land cover changes, accounting for 97% of the total. From 1981 to 2000, the NPP in the whole study region remarkably reduced due to obvious precipitation decrease and temperature rise. Between two periods of land use (about 10 years), the changes in climate are predicted to promote a decrease in NPP by 78 (±0.6) TgC, and integrated impacts of climate changes and land use to promote a decrease in NPP by 87(±0.8) TgC.

Late Holocene climatic history of northern Germany and Denmark: peat macrofossil investigations at Dosenmoor, Schleswig-Holstein, and Svanemose, Jutland

Plant macrofossil remains have been analysed from two raised peat bogs in northern Germany and Denmark. The quantified vegetation reconstructions of each profile were subjected to multivariate analyses to extract records of changing bog surface wetness (BSW), which are interpreted in these rain-fed bogs as being proxy climate signals. Age/depth models were constructed using radiocarbon dates and a number of drier and wetter phases were defined. The records both register cooler/wetter conditions around 2700, 1800 and 1400 cal. yr BP, and at the beginning of the Little Ice Age around AD 1250–1350. These rising bog water tables must have been reflected in poorer conditions for agriculture, and in particular near Dosenmoor where the profile records a catastrophic change to such conditions culminating at 2750–2600 cal. yr BP.

Late Holocene climatic history of northern Germany and Denmark: peat macrofossil investigations at Dosenmoor, Schleswig‐Holstein, and Svanemose, Jutland

Plant macrofossil remains have been analysed from two raised peat bogs in northern Germany and Denmark. The quantified vegetation reconstructions of each profile were subjected to multivariate analyses to extract records of changing bog surface wetness (BSW), which are interpreted in these rain‐fed bogs as being proxy climate signals. Age/depth models were constructed using radiocarbon dates and a number of drier and wetter phases were defined. The records both register cooler/wetter conditions around 2700, 1800 and 1400 cal. yr BP, and at the beginning of the Little Ice Age around AD 1250–1350. These rising bog water tables must have been reflected in poorer conditions for agriculture, and in particular near Dosenmoor where the profile records a catastrophic change to such conditions culminating at 2750–2600 cal. yr BP.

Midge-inferred Holocene climate history of two subalpine lakes in southern British Columbia, Canada

To investigate postglacial environmental changes in both the coastal and interior wet belts of British Columbia, fossil midges were analysed from two subalpine lakes, one adjacent to the lower Fraser canyon (Frozen Lake), and the other in Mount Revelstoke National Park (Eagle Lake). The midge stratigraphy for Frozen Lake revealed an abundance of rheophilous chironomid taxa and Simuliidae larvae, refecting the presence of an inflowing stream. An abundance of Chaoborus mandibles and Microtendipes during the early Holocene (c. 10100–7700 14C years BP, c. 11500–8500 cal. years BP) suggests warmer temperatures. A subsequent decline in the warm indicators and relative increases in cold stenotherms (Heterotrissocladius and Diamesa) indicate cooling until present day. This climate reconstruction is consistent with other quantitative and qualitative evidence for past climatic change in southern British Columbia. At Eagle Lake the warm indicators, Dicrotendipes and Polypedilum, are seen in the early Holocene (c. 8500–6730 14C years BP, c. 9600–7600 cal. years BP), but are absent during the mid-Holocene when cooler temperatures probably prevailed. In the late Holocene (c. 3800 14C years BP to present, c. 4200 cal. years BP to present) there is a resurgence of warm indicators, which contrasts with the evidence of continued cooling typically seen in reconstructions of southern British Columbia summer temperatures. The Eagle Lake record therefore appears to be anomalous. Multiproxy and multisite investigations are needed to reconstruct Holocene climatic changes more reliably.

Oxygen isotope records of goethite from ferricrete deposits indicate regionally varying Holocene climate change in the Rocky Mountain region, U.S.A.

Oxygen isotopes of goethite from ferricrete deposits were measured from both northern and southern Rocky Mountain localities to assess geographic variability in regional Holocene paleoclimate change. A ∼3.7‰ increase in oxygen isotope values of 14C-dated goethites in the northern Rocky Mountains suggests a regional-scale relative increase in amounts of isotopically heavy summer precipitation since the early Holocene. In contrast, oxygen isotope values from the southern Rocky Mountains increase abruptly ∼2.1‰ at ∼6200 14C yr B.P., then decrease ∼2.4‰ between ∼2000 14C yr B.P. and the present. We interpret this period of relatively high δ 18O values as evidence for a middle Holocene warm period combined with a relatively strong summer monsoon. These variable climate records suggest that the Rocky Mountains of the western United States have had a spatially heterogeneous Holocene climate history.

Regional ground surface temperature mapping from meteorological data

Evaluating ground surface temperature (GST) is common in applied and general geothermal research. Our main focus here is investigating GST for Switzerland because of its well-known impact on low-enthalpy resources, like borehole heat exchanger (BHE) utilization. Using mainly meteorological data, we determined the present-day GST distribution through different approaches. First, we analyzed the actual GST data from the last 20 years measured at the meteorological stations of the Swiss Meteorological Institute (SMI) by investigating recent climatic history and annual variation behavior. Recent climate change seems to have a higher impact on Alpine regions than on the Alpine Foreland. Next, we determined the GST altitude dependence in the range of 200–1800 m a.s.l., using nonlinear fitting approaches and investigated the relationship between GST and surface exposure. Contrary to previous publications, no universal correlation between GST and surface exposure was found, due to local and rapid changing meteorological conditions. Finally, we used a complete data set to consider meteorologically relevant data like soil moisture, wind speed, and vegetation cover and height. The measured GST was well reproduced for the case of low vegetation, except when covered by snow and for days of subzero surface air temperature (SAT). Other locations like urban areas could not be tested. Due to the complexity of physical interaction and the resulting assessment of large data sets, this approach is not suitable for determining regional GST distribution which we need as an input for BHE modeling. A relationship between GST and SAT was defined based on the data from the meteorological stations. By applying nonlinear approaches, we established three different altitude zones that require individual consideration. By further processing, an existing SAT map was converted into the first GST map of Switzerland. To verify this new map within the range of validity (up to altitudes of 1500 m a.s.l.), GST values extrapolated from boreholes were used as independent data sources. Generally, a fit with a standard deviation of ±1.0 K was achieved, but local deviations of 2 K also occurred. The new GST map of Switzerland provides useful estimates of regional GST, but not for local effects. It represents an important improvement in evaluating geothermal resources and determines regional GST distribution under vegetation and weather conditions typical of central Europe.

Antarctic oversnow traverse‐based southern hemisphere climate reconstruction

On 2 January 2003, the U.S. component of the International Trans Antarctic Scientific Expedition (U.S. ITASE) (Figure 1) arrived at the South Pole after completing more than 5000 km of oversnow traverses that included much of west Antarctica and a portion of east Antarctica (Figure 2). During the traverses, which were performed from 1999 through 2003, U.S. ITASE focused on collecting data that will allow the reconstruction of sub‐annual scale climate variability and changes in the chemistry of the atmosphere over the last 200+ years.ITASE is a multi‐disciplinary research program supported by 19 nations and endorsed by the Scientific Committee on Antarctic Research (SCAR) and the International Geosphere‐Biosphere Program (IGBP) [Mayewski and Goodwin, 1997]. It is designed to reconstruct the recent climate history of Antarctica through ice coring and related observations along a network of extensive intra‐continental traverses. The U.S. component of ITASE is supported by the Office of Polar Programs of the National Science Foundation. It includes scientific projects from the following institutions: Cold Regions Research and Engineering Laboratory‐U.S. Army, Desert Research Institute, NASA, Ohio State University, St. Olaf College, the University of Arizona, the University of Colorado, the University of Maine, and the University of Washington. Information concerning climate variability in the middle and high latitudes of the southern hemisphere is obtained by U.S. ITASE, through calibrations developed between US. ITASE ice core records and direct atmospheric observations [Kreutz et al., 2000; Meyerson et al., 2002; Schneider and Steig, 2002].

Holocene climatic changes and environmental history of Iturup Island, Kurile Islands, northwestern Pacific

The study of Holocene deposits on Iturup Island is very important for understanding palaeolandscape changes on the island. It is separated by deep straits from the neighbouring islands and was isolated during the last glacial maximum. Landscape changes over the last 40000 years and the role of refugia on vegetation development are discussed. Changes in natural processes in this region were controlled both by global climatic changes and by regional factors. Birch forests developed at the warming about 36-37 ka ago, whereas tundrapark landscape developed with the cooling of the last glacial maximum. Holocene environments reflect climatic changes and sea-level oscillations. The fluctuation of warm and cold currents influenced the landscape development. At the Holocene Optimum (about 6 ka) broadleaved forests with Quercus, Phellodendron, Carpinus, Juglans, Fagus, Fraxinus and Syinga occupied the Okhotsk side of central Iturup. Climate was warmer than present and the sum of active tempe]ratures (σ ≥10°C) was not less than 1800°C. The warming was coincident with the transgression with the highest sea level up to 3.5 m above present sea level (PSL). Numerous coastal lakes were formed at this time. A shallow strait occurred on the low Vetrovoy isthmus. The sea-level drop at 4700-4500 radiocarbon years BP led to the development of large dunefields only within bays with a flat coast due to the supply of sandy material from the inshore drainage zone. At the beginning of the late Holocene about 4000 BP the vegetation changed very little due to the warm current influence. Cool-temperate forests with dominant Quercus had a wide distribution, but the diversity of broadleaved genera decreased. A minor transgression occurred about 4100-4000 BP with a sea-level rise on about 2.5 m above PSL. Active accumulation of deposits took place in the coastal zone at this time. Great vegetation changes and climatic deterioration took place in the last 2000 years BP. Cool-temperate broadleaved forests were confined to the Okhotsk side of the central island. Grasslands and swamps also developed in the coastal lowlands at this time. A minor regression led to the formation of large dunefields. Isthmuses increased and coastal wetlands with lakes formed. The presence of marine diatoms in floodplain lake deposits indicates a sea-level rise at about 1060 ± 60 BP. At this time warming was not intensive, but was well pronounced. The last phase of active aeolian accumulation took place during the ‘Little Ice Age’ cooling and regression.

Reconstructing Late Holocene climate

Studying the past few millennia, the Late Holocene, can help us better understand modern‐day natural climate variability. With this in mind, a group of paleoclimate researchers and climate modelers recently convened at a workshop to discuss three distinct approaches to reconstructing Late Holocene climate history.

Paleoclimatic implications of pedogenic carbonates in Holocene soils of the Gangetic Plains, India

This study attempts to reconstruct the Holocene climatic history of the Indo-Gangetic Plains based on micromorphological characteristics and stable isotope composition of calcretes in a soil-chronoassociation between the Ramganga and Rapti rivers. The calcrete from the B2 horizon of older soils (QGH4–QGH5: 6500–13 500yearbp) consists of septaric and irregularly shaped nodules of dense micrite and diffused needles associated with the illuvial clay pedofeatures. Fabric of the calcretes of older soils show inclusion of soil constituents and precipitation of carbonates in between weathered layers of micas. Formation of this calcrete took place during the pedogenesis in an arid to semi-arid climate that also influenced vegetation and C4 type biomass such as Chenopodium and Typha angustata spread in the area. A change to warm and humid phase at 6500yearbp led to dissolution and reprecipitation of the calcretes. This led to the formation of blocky crystals and needles of calcite in voids and coarsening of the fabric in the lower horizons. The vegetation pattern also changed to woodland with Anogeissus and Tecomella spp. The younger soils (<2500yearbp) show secondary carbonate accumulation associated mainly along the voids in lower parts of the profiles. These are relatively coarse textured with little or no inclusion of soil constituents. This coarse grained calcrete results from capillary rise from a fluctuating water table in a sub-humid climate similar to present.Carbon and oxygen isotope data suggest that the formation of pedogenic carbonate in old soils (QGH4 and QGH5) by evapotranspiration during arid to semi-arid climate. In the upper horizons, the carbonates are depleted in 13C as their formation was influenced by the sparse vegetation and low soil respiration rate. In the lower horizons, the carbonates show enrichment of 13C due its extensive dissolution–reprecipitation during the humid climate. The younger soils showed the enrichment of 13C in their calcretes and support their formation from fluctuating shallow groundwater table. The oxygen isotope values similar to that of meteoric water of the area indicate calcrete precipitation in equilibrium with the soil water.

Vegetation and climate in the lower reaches of the Yana River during the Holocene

The Holocene climate history of the region near the mouth of the Yana River in Yakutia (Sakha Republic) is reconstructed from two sections of the Kazach'ye and Khocho peat bogs along the banks of the Yana River. Spore‐pollen analysis and an information‐statistical method are used to reconstruct temperature and precipitation histories that are compared with present‐day conditions.

Wisconsinan and Holocene Climate History from an Ice Core at Taylor Dome, Western Ross Embayment, Antarctica

Wisconsinan and Holocene Climate History from an Ice Core at Taylor Dome, Western Ross Embayment, Antarctica

Genetic differentiation of Anopheles claviger s.s. in France and neighbouring countries.

An investigation of polymorphism of 11 autosomal and one sex-linked allozyme loci was made on 18 samples of Anopheles claviger Meigen (Diptera: Culicidae) from localities across France and neighbouring sites in Germany and Switzerland, plus one sample of Anopheles petragnani Del Vecchio from the French Pyrénées. Genetic differentiation between these two sibling species was confirmed (Nei genetic distance 0.33-0.44) and two genetically distinct groups of populations were identified within An. claviger. These two forms of An. claviger showed contiguous geographical distributions, Group I found across western and Central France, Group II in eastern France and nearby parts of Germany and Switzerland. The two groups were in contact in a region near the Rhone Valley where two intermediate samples were found. The taxonomic significance of this finding is discussed in the context of the recent climatic history of Europe and in relation to the vector potential of each member of the An. claviger complex.

Wisconsinan and holocene climate history from an ice core at taylor dome, western ross embayment, antarctica

Geochemical data and geophysical measurements from a 554‐m ice‐core from Taylor Dome, East Antarctica, provide the basis for climate reconstruction in the western Ross Embayment through the entire Wisconsinan and Holocene. In comparison with ice cores from central East and West Antarctica, Taylor Dome shows greater variance of temperature, snow accumulation, and aerosol concentrations, reflecting significant variability in atmospheric circulation and air mass moisture content. Extreme aridity during the last glacial maximum at Taylor Dome reflects both colder temperatures and a shift in atmospheric circulation patterns associated with the advance of the Ross Sea ice sheet and accounts for regional alpine glacier retreats and high lake levels in the Dry Valleys. Inferred relationships between spatial accumulation gradients and ice sheet configuration indicate that advance of the Ross Sea ice sheet began in late marine isotope stage 5 or early stage 4. Precise dating of the Taylor Dome core achieved by trace‐gas correlation with central Greenland ice cores shows that abrupt deglacial warming at Taylor Dome was near‐synchronous with the ∼14.6 ka warming in central Greenland and lags the general warming trend in other Antarctic ice cores by at least 3000 years. Deglacial warming was following by a warm interval and transient cooling between 14.6 and 11.7 ka, synchronous with the Bølling/Allerød warming and Younger Dryas cooling events in central Greenland, and out of phase with the Antarctic Cold Reversal recorded in the Byrd (West Antarctica) ice core. Rapid climate changes during marine isotope stages 4 and 3 at Taylor Dome are similar in character to, and may be in phase with, the Northern Hemisphere stadial–interstadial (Dansgaard–Oeschger) events. Results from Taylor Dome illustrate the importance of obtaining ice cores from multiple Antarctic sites, to provide wide spatial coverage of past climate and ice dynamics.

Holocene climate history of Geographical Society Ø, East Greenland — evidence from lake sediments

Sediment cores from two lakes in the outer coastal region of East Greenland were investigated for chronology, lithology, palynology, and biogeochemistry. A 10 m long sequence recovered in Basaltsø comprises the entire lake history following the last glaciation of the area, probably during the Preboreal oscillation. This is indicated by a succession from glacial via glaciolimnic to limnic sediments. Deglaciation of the area was associated with a high sedimentation rate, mirrored also in the basal part of a 2.6 m long core from a smaller lake (B1) about 1 km south of Basaltsø. Limnic sedimentation without glacial influence commenced about 10 000 cal. yr BP according to radiocarbon-dated terrestrial plant remains. Biogeochemical and palynological data indicate an early Holocene climatic optimum from 9000 to 6500 cal. yr BP A climatic deterioration began at 6500 cal. yr BP with an increase in snow accumulation, documented by a change in the pollen assemblage and a coinciding change in the grain-size distribution. At least since 5000 cal. yr BP, a decrease in the biogeochemical parameters in both lake sediment successions indicates a temperature decline. This deterioration culminated at about 3000–1000 cal. yr BP, when the climate was cold and dry. A slight warming is indicated in the pollen assemblage between ca. 1000 and 800 cal. yr BP. Following a subsequent rise in precipitation, cooling during the Little Ice Age is mirrored in lowest dwarf shrub pollen percentages and in low contents of organic components.

A Late Holocene desiccation of Lake Hoare and Lake Fryxell, McMurdo Dry Valleys, Antarctica

Stable isotope data from waters of lakes in the McMurdo Dry Valleys (MDV) of southern Victoria Land, Antarctica are presented in order to establish the climatic history of this region over the past two millennia. New data from Lake Fryxell and Lake Hoare in Toylor Valley, along with previously published data from Lake Vanda, Wright Valley and Lake Bonney, Taylor Valley are used to infer the recent climatic history of MDV. Lakes Vanda, Fryxell and Bonney appear to have lost their ice covers and evaporated to small, hypersaline ponds by 1000 to ~1200 yr BP. Lake Hoare either desiccated or did not exist prior to 1200 yr BP. These data indicate a major lowering of lake level prior to ~1000 yr BP, followed by a warmer and/or more humid climate since then.