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High‐resolution records from past interglacial climates help constrain future responses to global warming, yet are rare. Here, we produce seasonally resolved climate records from subarctic‐Canada using micron‐scale measurements of oxygen isotopes (δ18O) in speleothems with apparent annual growth bands from three interglacial periods—Marine Isotope Stages (MIS) 11, 9, and 5e. We find 3‰ lower δ18O values during MIS 11 than MIS 5e, despite MIS 11 likely being warmer. We explore controls on high‐latitude speleothem δ18O and suggest low MIS 11 δ18O values reflect greater contribution of cold‐season precipitation to dripwater from longer annual ground thaw durations. Other potential influences include changes in precipitation source and/or increased fraction of cold‐season precipitation from diminished sea ice in MIS 11. Our study highlights the potential for high‐latitude speleothems to yield detailed isotopic records of Northern Hemisphere interglacial climates beyond the reach of Greenland ice cores and offers a framework for interpreting them. Plain Language Summary: Few climate records pre‐dating the last ice age exist from high‐latitude North America, which inhibits our understanding of how regions with permafrost responded to past warming and how they might change in the future. Here, we help fill this data gap by using six speleothems (cave mineral deposits) from a cave in the Northwest Territories, Canada to produce climate records that span thousands of years during former warm periods of Earth's history. We find that speleothems that grew during an exceptionally warm super‐interglacial period 400,000 years ago have 3‰ lower oxygen isotope (δ18O) values compared to those that grew during a likely cooler interglacial 125,000 years ago. We explore potential explanations for the difference in δ18O across interglacials, and suggest that lower δ18O values during warmer periods reflect greater infiltration of cool‐season precipitation with longer annual ground thaw durations. This study highlights the importance of high‐latitude speleothems to provide detailed climate records beyond the range available from Greenland ice cores. Key Points: Long high‐latitude terrestrial climate records are rare in the Northern HemisphereHigh‐latitude speleothems can provide ultra‐high‐resolution climate records beyond the reach of Greenland ice coresMean oxygen isotopes of Arctic and subarctic speleothems likely are controlled by annual ground thaw durations [ABSTRACT FROM AUTHOR]

The cave site of Lapa do Picareiro, Portugal contains a deep (~10 m) sedimentary sequence representing much of the Middle and Upper Paleolithic, with abundant animal bones, lithic/bone/shell artifacts, and charcoal/ash in hearths. A deposition model based on 49 radiocarbon ages demonstrates average sedimentation rates of 0.1–0.3 mm a −1 between 9 and 45 ka. Extrapolation suggests an age at the base of the excavation of 65–78 ka. The cave sediments are primarily limestone éboulis derived from roof spalling, and muddy fine sediment derived from weathered soil infiltrating through bedrock joints and crevices. Bone preservation in the cave is good and disturbance by bioturbation, dissolution, or erosional processes appears to be limited. Most sedimentological parameters vary conservatively with depth, indicating stable sediment sources over time. Several parameters show good agreement with paleoclimate records over the radiocarbon‐dated section. The cold‐arid Heinrich stadials are represented by coarse‐clast beds with little fine sediment and magnetic susceptibility minima, and mild Greenland interstadials correspond with muddy beds and sharp peaks in magnetic susceptibility. This study complements ongoing archaeological excavation at the site and confirms that the sequence has the proper age, resolution, and preservation to inform on Late Pleistocene cultural and climatic transitions. [ABSTRACT FROM AUTHOR]

Schmidt, S., Wagner, B., Heiri, O., Klug, M., Bennike, O. & Melles, M. 2010: Chironomids as indicators of the Holocene climatic and environmental history of two lakes in Northeast Greenland. Boreas, 10.1111/j.1502-3885.2010.00173.x. ISSN 0300-9483. Two Holocene sediment sequences from arctic lakes on Store Koldewey, an island in Northeast Greenland, were investigated for fossil chironomid assemblages. A total of 18 and 21 chironomid taxa were identified in 290- and 252-cm-long sediment sequences from Duck Lake and Hjort Lake, respectively. The chironomid assemblages were very similar in the two lakes. Canonical correspondence analysis (CCA) was used to compare fossil chironomid assemblages from Store Koldewey with chironomid assemblages and environmental conditions presently found in Canadian Arctic lakes and, hence, to infer environmental changes for Northeast Greenland. The first chironomids appeared at c. 9500 cal. a BP in Hjort Lake, and 500 years later in Duck Lake. Taxa typical for cold and nutrient-poor arctic lakes dominated the earliest assemblages. Chironomid assemblages with taxa typical of higher summer air temperatures and lakes with higher nutrient availability occur between 8000 and 5000 cal. a BP. This period probably marks the regional Holocene thermal maximum, which is relatively late compared with some palaeoenvironmental records from East Greenland. One possible reason could be the location of Store Koldewey at the very outer coast, with local climatic conditions strongly influenced by the cold East Greenland Current. From around 5000 cal. a BP, chironomid assemblages in Duck Lake and Hjort Lake again became more typical of those presently found in Northeast Greenland, indicating relatively cold and nutrient-poor conditions. This shift coincides with an increase of ice-rafting debris off East Greenland and an intensification of the East Greenland Current. [ABSTRACT FROM AUTHOR]

The role of the Arctic in future global change processes is predicted to be important because of the large carbon (C) stocks contained in frozen soils and peatlands. Lakes are an important component of arctic landscapes although their role in storing C is not well prescribed. The area around Kangerlussuaq, SW Greenland (66–68°N, 49–54°W) has extremely high lake density, with ∼20 000 lakes that cover about 14% of the land area. C accumulation rates and standing stock (kg C m−2), representing late- to mid-Holocene C burial, were calculated from AMS 14C-dated sediment cores from 11 lakes. Lake ages range from ∼10 000 cal yr bp to ∼5400 cal yr bp, and reflect the withdrawal of the ice sheet from west to east. Total standing stock of C accumulated in the studied lakes for the last ∼8000 years ranged from 28 to 71 kg C m−2, (mean: ∼42 kg C m−2). These standing stock determinations yield organic C accumulation rates of 3.5–11.5 g C m−2 yr−1 (mean: ∼6 g C m−2 yr−1) for the last 4500 years. Mean C accumulation rates are not different for the periods 8–4.5 and 4.5–0 ka, despite cooling trends associated with the neoglacial period after 4.5 ka. We used the mean C standing stock to estimate the total C pool in small lakes (<100 ha) of the Kangerlussuaq region to be ∼4.9 × 1013 g C. This C stock is about half of that estimated for the soil pool in this region (but in 5% of the land area) and indicates the importance of incorporating lakes into models of regional C balance at high latitudes. [ABSTRACT FROM AUTHOR]

Northern Hemisphere climate history through and following the Last Glacial Maximum is recorded in detail in ice cores from Greenland. However, the period between Greenland Interstadials 1 and 2 (15–23 ka), i.e. the period of deglaciation following the last major glaciation, has been difficult to resolve in great detail. We here offer a new subdivision of this in the NGRIP, GRIP and GISP2 ice cores, by newly introducing spectral trend analysis to the study of climate-related data series from ice cores. This analysis reveals patterns of change and discontinuity in the waveform properties of a data series, relating to the environmental (including climatic) history of accumulation of the rock or ice record. The application allows high-resolution correlation between the ice cores, and a greatly improved subdivision of the study interval. Nine climatic phases are recognized, within which more identifiable events can also be correlated between the three locations. [ABSTRACT FROM AUTHOR]

A 2.9 m long sedimentary record was studied from a small lake, here referred to as Duck Lake, located at 76°25′N, 18°45′W on Store Koldewey, an elongated island off the coast of Northeast Greenland. The sediments were investigated for their geophysical and biogeochemical characteristics, and for their fossil chironomid assemblages. Organic matter began to accumulate in the lake at 9.1 cal. kyr BP, which provides a minimum age for the deglaciation of the basin. Although the early to mid-Holocene is known as a thermal maximum in East Greenland, organic matter accumulation in the lake remained low during the early Holocene, likely due to late plant immigration and lack of nutrient availability. Organic matter accumulation increased during the middle and late Holocene, when temperatures in East Greenland gradually decreased. Enhanced soil formation probably led to higher nutrient availability and increased production in the lake. Chironomids are abundant throughout the record after 9.1 cal. kyr BP and seem to react sensitively to changes in temperature and nutrient availability. It is concluded that relative temperature reconstructions based on biogeochemical data have to be regarded critically, particularly in the period shortly after deglaciation when nutrient availability was low. Chironomids may be a suitable tool for climatic reconstructions even in those high arctic environments. However, a better understanding of the ecology of chironomids under these extreme conditions is needed. [ABSTRACT FROM AUTHOR]

Three NW Iberia Cantabrian Mountain pollen records are presented. They reflect the main Holocene climatic shifts in the North Atlantic region as recorded in the isotopic data from Greenland ice, Irish speleothems and reconstructed sea surface temperatures. Two brief forest regression episodes reconstructed from pollen may be synchronous with GH-11.2 and GH-8.2 events. At mid-altitude, two woodland expansion phases (7000–6000 14 C yr BP and 4000–2500 14 C yr BP) are separated by a phase of heaths and peat deposits. Major woodland declines occurred during the Galician–Roman Period (which includes the Bronze Age, the Iron Age and the Roman occupation) and from the end of the Medieval Period. The pollen data, backed up by archaeological and historical sources, suggest climatic impact of the Iron Age Cold Period, but are indecisive concerning the Little Ice Age. However, the pollen records do not support any significant ‘Neoglacial’ period (4000–3000 14 C yr BP) influence on NW Iberia. [ABSTRACT FROM AUTHOR]