Papers on last interglacial climate
Posted by Ari Jokimäki on June 21, 2012
This is a list of papers on last interglacial (so called Eemian interglacial, between about 130000 and 110000 years ago) climate conditions with emphasis on papers that discuss last interglacial as an indicator of future climate conditions and consequences. The list is not complete, and will most likely be updated in future in order to make it more thorough and more representative.
European climate optimum and enhanced Greenland melt during the Last Interglacial – Goñi et al. (2012) “The Last Interglacial climatic optimum, ca. 128 ka, is the most recent climate interval significantly warmer than present, providing an analogue (albeit imperfect) for ongoing global warming and the effects of Greenland Ice Sheet (GIS) melting on climate over the coming millennium. While some climate models predict an Atlantic meridional overturning circulation (AMOC) strengthening in response to GIS melting, others simulate weakening, leading to cooling in Europe. Here, we present evidence from new proxy-based paleoclimate and ocean circulation reconstructions that show that the strongest warming in western Europe coincided with maximum GIS meltwater runoff and a weaker AMOC early in the Last Interglacial. By performing a series of climate model sensitivity experiments, including enhanced GIS melting, we were able to simulate this configuration of the Last Interglacial climate system and infer information on AMOC slowdown and related climate effects. These experiments suggest that GIS melt inhibited deep convection off the southern coast of Greenland, cooling local climate and reducing AMOC by ∼24% of its present strength. However, GIS melt did not perturb overturning in the Nordic Seas, leaving heat transport to, and thereby temperatures in, Europe unaffected.” Maria Fernanda Sánchez Goñi, Pepijn Bakker, Stéphanie Desprat, Anders E. Carlson, Cédric J. Van Meerbeeck, Odile Peyron, Filipa Naughton, William J. Fletcher, Frédérique Eynaud, Linda Rossignol and Hans Renssen, Geology, v. 40 no. 7 p. 627-630, doi: 10.1130/G32908.1. [FULL TEXT]
Sr-Nd-Pb Isotope Evidence for Ice-Sheet Presence on Southern Greenland During the Last Interglacial – Colville et al. (2012) “To ascertain the response of the southern Greenland Ice Sheet (GIS) to a boreal summer climate warmer than at present, we explored whether southern Greenland was deglaciated during the Last Interglacial (LIG), using the Sr-Nd-Pb isotope ratios of silt-sized sediment discharged from southern Greenland. Our isotope data indicate that no single southern Greenland geologic terrane was completely deglaciated during the LIG, similar to the Holocene. Differences in sediment sources during the LIG relative to the early Holocene denote, however, greater southern GIS retreat during the LIG. These results allow the evaluation of a suite of GIS models and are consistent with a GIS contribution of 1.6 to 2.2 meters to the ≥4-meter LIG sea-level highstand, requiring a significant sea-level contribution from the Antarctic Ice Sheet.” Elizabeth J. Colville, Anders E. Carlson, Brian L. Beard, Robert G. Hatfield, Joseph S. Stoner, Alberto V. Reyes, David J. Ullman, Science 29 July 2011: Vol. 333 no. 6042 pp. 620-623, DOI: 10.1126/science.1204673. [FULL TEXT]
Probabilistic assessment of sea level during the last interglacial stage – Kopp et al. (2009) “With polar temperatures ~3–5 °C warmer than today, the last interglacial stage (~125 kyr ago) serves as a partial analogue for 1–2 °C global warming scenarios. Geological records from several sites indicate that local sea levels during the last interglacial were higher than today, but because local sea levels differ from global sea level, accurately reconstructing past global sea level requires an integrated analysis of globally distributed data sets. Here we present an extensive compilation of local sea level indicators and a statistical approach for estimating global sea level, local sea levels, ice sheet volumes and their associated uncertainties. We find a 95% probability that global sea level peaked at least 6.6 m higher than today during the last interglacial; it is likely (67% probability) to have exceeded 8.0 m but is unlikely (33% probability) to have exceeded 9.4 m. When global sea level was close to its current level (≥-10 m), the millennial average rate of global sea level rise is very likely to have exceeded 5.6 m kyr-1 but is unlikely to have exceeded 9.2 m kyr-1. Our analysis extends previous last interglacial sea level studies by integrating literature observations within a probabilistic framework that accounts for the physics of sea level change. The results highlight the long-term vulnerability of ice sheets to even relatively low levels of sustained global warming.” Robert E. Kopp, Frederik J. Simons, Jerry X. Mitrovica, Adam C. Maloof & Michael Oppenheimer, Nature 462, 863-867 (17 December 2009) | doi:10.1038/nature08686. [Full text]
Response of the southern Greenland Ice Sheet during the last two deglaciations – Carlson et al. (2012) “The retreat of the southern Greenland Ice Sheet (GIS) during the last deglaciation (Termination I: TI) is poorly dated by conventional means; there is even greater uncertainty about the penultimate deglaciation (Termination II: TII), leading to the assumption that the southern GIS has a significant lag in its response to deglacial warming. Here we use geochemical terrestrial sediment proxies ([Fe] and [Ti]) from a well-studied southern Greenland marine sediment sequence to examine the behavior of the southern GIS during TI and TII. Our records show that during TI and TII the southern GIS response was essentially synchronous with deglacial North Atlantic warming, implying greater climate sensitivity than previously assumed. During TI, elevated ablation lasted ~5 k.y., whereas ablation remained elevated for ~12 k.y. during TII, suggesting a reduced southern GIS during TII that contributed a significant fraction of the higher sea level during the subsequent interglacial.” Anders E. Carlson, Joseph S. Stoner, Jeffrey P. Donnelly and Claude Hillaire-Marcel, Geology May 2008 v. 36, no. 5, p. 359-362, doi: 10.1130/G24519A.1. [FULL TEXT]
The climate in Europe during the Eemian: a multi-method approach using pollen data – Brewer et al. (2008) “The Last Interglacial period, the Eemian, offers a testbed for comparing climate evolution throughout an interglacial with the current warm period. We present here results from climatic reconstructions from 17 sites distributed across the European continent, allowing an assessment of trends and regional averages of climate changes during this period. We use a multi-method approach to allow for an improved assessment of the uncertainties involved in the reconstruction. In addition, the method takes into account the errors associated with the age model. The resulting uncertainties are large, but allow a more robust assessment of the reconstructed climatic variations than in previous studies. The results show a traditional three-part Eemian, with an early optimum, followed by slight cooling and eventually a sharp drop in both temperatures and precipitation. This sequence is however, restricted to the north, as this latter change is not observed in the south where temperatures remain stable for longer. These variations led to marked variation in the latitudinal temperature gradient during the Eemian. The difference between the two regions is also noticeable in the magnitude of changes, with greater variations in the north than the south. Some evidence is found for changes in lapse rates, however, a greater number of sites is needed to confirm this.” S. Brewer, J. Guiot, M.F. Sánchez-Goñi, S. Klotz, Quaternary Science Reviews, Volume 27, Issues 25–26, December 2008, Pages 2303–2315, http://dx.doi.org/10.1016/j.quascirev.2008.08.029.
The Deep Ocean During the Last Interglacial Period – Duplessy et al. (2007) “Oxygen isotope analysis of benthic foraminifera in deep sea cores from the Atlantic and Southern Oceans shows that during the last interglacial period, North Atlantic Deep Water (NADW) was 0.4° ± 0.2°C warmer than today, whereas Antarctic Bottom Water temperatures were unchanged. Model simulations show that this distribution of deep water temperatures can be explained as a response of the ocean to forcing by high-latitude insolation. The warming of NADW was transferred to the Circumpolar Deep Water, providing additional heat around Antarctica, which may have been responsible for partial melting of the West Antarctic Ice Sheet.” J. C. Duplessy, D. M. Roche and M. Kageyama, Science 6 April 2007: Vol. 316 no. 5821 pp. 89-91, DOI: 10.1126/science.1138582. [Full text]
Evidence for last interglacial chronology and environmental change from Southern Europe – Brauer et al. (2007) “Establishing phase relationships between earth-system components during periods of rapid global change is vital to understanding the underlying processes. It requires records of each component with independent and accurate chronologies. Until now, no continental record extending from the present to the penultimate glacial had such a chronology to our knowledge. Here, we present such a record from the annually laminated sediments of Lago Grande di Monticchio, southern Italy. Using this record we determine the duration (17.70 ± 0.20 ka) and age of onset (127.20 ± 1.60 ka B.P.) of the last interglacial, as reflected by terrestrial ecosystems. This record also reveals that the transitions at the beginning and end of the interglacial spanned only ≈100 and 150 years, respectively. Comparison with records of other earth-system components reveals complex leads and lags. During the penultimate deglaciation phase relationships are similar to those during the most recent deglaciation, peaks in Antarctic warming and atmospheric methane both leading Northern Hemisphere terrestrial warming. It is notable, however, that there is no evidence at Monticchio of a Younger Dryas-like oscillation during the penultimate deglaciation. Warming into the first major interstadial event after the last interglacial is characterized by markedly different phase relationships to those of the deglaciations, warming at Monticchio coinciding with Antarctic warming and leading the atmospheric methane increase. Diachroneity is seen at the end of the interglacial; several global proxies indicate progressive cooling after ≈115 ka B.P., whereas the main terrestrial response in the Mediterranean region is abrupt and occurs at 109.50 ± 1.40 ka B.P.” Achim Brauer, Judy R. M. Allen, Jens Mingram, Peter Dulski, Sabine Wulf, and Brian Huntley, PNAS January 9, 2007 vol. 104 no. 2 450-455, doi: 10.1073/pnas.0603321104. [Full text]
Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise – Overpeck et al. (2006) “Sea-level rise from melting of polar ice sheets is one of the largest potential threats of future climate change. Polar warming by the year 2100 may reach levels similar to those of 130,000 to 127,000 years ago that were associated with sea levels several meters above modern levels; both the Greenland Ice Sheet and portions of the Antarctic Ice Sheet may be vulnerable. The record of past ice-sheet melting indicates that the rate of future melting and related sea-level rise could be faster than widely thought.” Jonathan T. Overpeck, Bette L. Otto-Bliesner, Gifford H. Miller, Daniel R. Muhs, Richard B. Alley and Jeffrey T. Kiehl, Science 24 March 2006: Vol. 311 no. 5768 pp. 1747-1750, DOI: 10.1126/science.1115159. [FULL TEXT]
Simulating Arctic Climate Warmth and Icefield Retreat in the Last Interglaciation – Otto-Bliesner et al. (2006) “In the future, Arctic warming and the melting of polar glaciers will be considerable, but the magnitude of both is uncertain. We used a global climate model, a dynamic ice sheet model, and paleoclimatic data to evaluate Northern Hemisphere high-latitude warming and its impact on Arctic icefields during the Last Interglaciation. Our simulated climate matches paleoclimatic observations of past warming, and the combination of physically based climate and ice-sheet modeling with ice-core constraints indicate that the Greenland Ice Sheet and other circum-Arctic ice fields likely contributed 2.2 to 3.4 meters of sea-level rise during the Last Interglaciation.” Bette L. Otto-Bliesner, Shawn J. Marshall, Jonathan T. Overpeck, Gifford H. Miller, Aixue Hu and CAPE Last Interglacial Project members, Science 24 March 2006: Vol. 311 no. 5768 pp. 1751-1753, DOI: 10.1126/science.1120808. [FULL TEXT]
A model-data comparison of European temperatures in the Eemian interglacial – Kaspar et al. (2005) “We present a comparison of reconstructed and simulated January and July temperatures in Europe for a time slice (∼125 kyr BP) within the last interglacial (Eemian, ∼127–116 kyr BP). The reconstructions, based on pollen and plant macrofossils, were performed on 48 European sites using a method based on probability density functions (pdf-method). The reconstructed most probable climate values were compared with a global climate simulation which was realized with a coupled ocean-atmosphere general circulation model. Orbital parameters and greenhouse gas concentrations have been adapted to conditions at 125 kyr BP. Reconstructions and simulation are concordant in showing higher temperatures than today over most parts of Europe in summer and in revealing a west-east-gradient in winter temperature differences with increasing anomalies toward eastern Europe. The results indicate that differences in the orbital parameters are sufficient to explain the reconstructed Eemian temperature patterns.” Kaspar, F., N. Kühl, U. Cubasch, and T. Litt (2005), A model-data comparison of European temperatures in the Eemian interglacial, Geophys. Res. Lett., 32, L11703, doi:10.1029/2005GL022456. [Full text]
Increased seasonality in Middle East temperatures during the last interglacial period – Felis et al. (2004) “The last interglacial period (about 125,000 years ago) is thought to have been at least as warm as the present climate. Owing to changes in the Earth’s orbit around the Sun, it is thought that insolation in the Northern Hemisphere varied more strongly than today on seasonal timescales, which would have led to corresponding changes in the seasonal temperature cycle. Here we present seasonally resolved proxy records using corals from the northernmost Red Sea, which record climate during the last interglacial period, the late Holocene epoch and the present. We find an increased seasonality in the temperature recorded in the last interglacial coral. Today, climate in the northern Red Sea is sensitive to the North Atlantic Oscillation, a climate oscillation that strongly influences winter temperatures and precipitation in the North Atlantic region. From our coral records and simulations with a coupled atmosphere–ocean circulation model, we conclude that a tendency towards the high-index state of the North Atlantic Oscillation during the last interglacial period, which is consistent with European proxy records, contributed to the larger amplitude of the seasonal cycle in the Middle East.” Thomas Felis, Gerrit Lohmann, Henning Kuhnert, Stephan J. Lorenz, Denis Scholz, Jürgen Pätzold, Saber A. Al-Rousan & Salim M. Al-Moghrabi, Nature 429, 164-168 (13 May 2004) | doi:10.1038/nature02546. [Full text]
Timing, Duration, and Transitions of the Last Interglacial Asian Monsoon – Yuan et al. (2004) “Thorium-230 ages and oxygen isotope ratios of stalagmites from Dongge Cave, China, characterize the Asian Monsoon and low-latitude precipitation over the past 160,000 years. Numerous abrupt changes in 18O/16O values result from changes in tropical and subtropical precipitation driven by insolation and millennial-scale circulation shifts. The Last Interglacial Monsoon lasted 9.7 ± 1.1 thousand years, beginning with an abrupt (less than 200 years) drop in 18O/16O values 129.3 ± 0.9 thousand years ago and ending with an abrupt (less than 300 years) rise in 18O/16O values 119.6 ± 0.6 thousand years ago. The start coincides with insolation rise and measures of full interglacial conditions, indicating that insolation triggered the final rise to full interglacial conditions.” Daoxian Yuan, Hai Cheng, R. Lawrence Edwards, Carolyn A. Dykoski, Megan J. Kelly, Meiliang Zhang, Jiaming Qing, Yushi Lin, Yongjin Wang, Jiangyin Wu, Jeffery A. Dorale, Zhisheng An and Yanjun Cai, Science 23 April 2004: Vol. 304 no. 5670 pp. 575-578, DOI: 10.1126/science.1091220. [Full text]
Continental European Eemian and early Würmian climate evolution: comparing signals using different quantitative reconstruction approaches based on pollen – Klotz et al. (2003) “Analyses of Eemian climate dynamics based on different reconstruction methods were conducted for several pollen sequences in the northern alpine foreland. The modern analogue and mutual climate sphere techniques used, which are briefly presented, complement one another with respect to comparable results. The reconstructions reveal the occurrence of at least two similar thermal periods, representing temperate oceanic conditions warmer and with a higher humidity than today. Intense changes of climate processes become obvious with a shift of winter temperatures of about 15 °C from the late Rissian to the first thermal optimum of the Eemian. The transition shows a pattern of summer temperatures and precipitation increasing more rapidly than winter temperatures. With the first optimum during the Pinus–Quercetum mixtum–Corylus phase (PQC) at an early stage of the Eemian and a second optimum period at a later stage, which is characterised by widespread Carpinus, climate gradients across the study area were less intense than today. Average winter temperatures vary between −1.9 and 0.4 °C (present-day −3.6 to 1.4 °C), summer temperatures between 17.8 and 19.6 °C (present-day 14 to 18.9 °C). The timberline expanded about 350 m when compared to the present-day limit represented by Pinus mugo. Whereas the maximum of temperature parameters is related to the first optimum, precipitation above 1100 mm is higher during the second warm period concomitant to somewhat reduced temperatures. Intermediate, smaller climate oscillations and a cooling becomes obvious, which admittedly represent moderate deterioration but not extreme chills. During the boreal semicontinental Eemian Pinus–Picea–Abies phase, another less distinct fluctuation occurs, initiating the oscillating shift from temperate to cold conditions.” Stefan Klotz, Joel Guiot, Volker Mosbrugger, Global and Planetary Change, Volume 36, Issue 4, May 2003, Pages 277–294, http://dx.doi.org/10.1016/S0921-8181(02)00222-9.
Last Interglacial Climates – Kukla et al. (2002) “The last interglacial, commonly understood as an interval with climate as warm or warmer than today, is represented by marine isotope stage (MIS) 5e, which is a proxy record of low global ice volume and high sea level. It is arbitrarily dated to begin at approximately 130,000 yr B.P. and end at 116,000 yr B.P. with the onset of the early glacial unit MIS 5d. The age of the stage is determined by correlation to uranium–thorium dates of raised coral reefs. The most detailed proxy record of interglacial climate is found in the Vostok ice core where the temperature reached current levels 132,000 yr ago and continued rising for another two millennia. Approximately 127,000 yr ago the Eemian mixed forests were established in Europe. They developed through a characteristic succession of tree species, probably surviving well into the early glacial stage in southern parts of Europe. After ca. 115,000 yr ago, open vegetation replaced forests in northwestern Europe and the proportion of conifers increased significantly farther south. Air temperature at Vostok dropped sharply. Pulses of cold water affected the northern North Atlantic already in late MIS 5e, but the central North Atlantic remained warm throughout most of MIS 5d. Model results show that the sea surface in the eastern tropical Pacific warmed when the ice grew and sea level dropped. The essentially interglacial conditions in southwestern Europe remained unaffected by ice buildup until late MIS 5d when the forests disappeared abruptly and cold water invaded the central North Atlantic ca. 107,000 yr ago.” George J. Kukla, Michael L. Bender, Jacques-Louis de Beaulieu, Gerard Bond, Wallace S. Broecker, Piet Cleveringa, Joyce E. Gavin, Timothy D. Herbert, John Imbrie, Jean Jouzel, Lloyd D. Keigwin, Karen-Luise Knudsen, Jerry F. McManus, Josef Merkt, Daniel R. Muhs, Helmut Müller, Richard Z. Poore, Stephen C. Porter, Guy Seret, Nicholas J. Shackleton, Charles Turner, Polychronis C. Tzedakis, Isaac J. Winograd, Quaternary Research, Volume 58, Issue 1, July 2002, Pages 2–13, http://dx.doi.org/10.1006/qres.2001.2316. [Full text]
High-resolution record of climate stability in France during the last interglacial period – Rioual et al. (2001) “The last interglacial period (127–110 kyr ago) has been considered to be an analogue to the present interglacial period, the Holocene, which may help us to understand present climate evolution. But whereas Holocene climate has been essentially stable in Europe, variability in climate during the last interglacial period has remained unresolved, because climate reconstructions from ice cores, continental records and marine sediment cores give conflicting results for this period. Here we present a high-resolution multi-proxy lacustrine record of climate change during the last interglacial period, based on oxygen isotopes in diatom silica, diatom assemblages and pollen–climate transfer functions from the Ribains maar in France. Contrary to a previous study, our data do not show a cold event interrupting the warm interglacial climate. Instead, we find an early temperature maximum with a transition to a colder climate about halfway through the sequence. The end of the interglacial period is clearly marked by an abrupt change in all proxy records. Our study confirms that in southwestern Europe the last interglacial period was a time of climatic stability and is therefore still likely to represent a useful analogue for the present climate.” Patrick Rioual, Valérie Andrieu-Ponel, Miri Rietti-Shati, Richard W. Battarbee, Jacques-Louis de Beaulieu, Rachid Cheddadi, Maurice Reille, Helena Svobodova & Aldo Shemesh, Nature 413, 293-296 (20 September 2001) | doi:10.1038/35095037.
Comparison of the last interglacial climate simulated by a coupled global model of intermediate complexity and an AOGCM – Kubatzki et al. (2000) “The climate at the Last Interglacial Maximum (125 000 years before present) is investigated with the atmosphere-ocean general circulation model ECHAM-1/LSG and with the climate system model of intermediate complexity CLIMBER-2. Comparison of the results of the two models reveals broad agreement in most large-scale features, but also some discrepancies. The fast turnaround time of CLIMBER-2 permits one to perform a number of sensitivity experiments to (1) investigate the possible reasons for these differences, in particular the impact of different freshwater fluxes to the ocean, (2) analyze the sensitivity of the results to changes in the definition of the modern reference run concerning CO2 levels (preindustrial versus “present”), and (3) estimate the role of vegetation in the changed climate. Interactive vegetation turns out to be capable of modifying the initial climate signals significantly, leading especially to warmer winters in large parts of the Northern Hemisphere, as indicated by various paleodata. Differences due to changes in the atmospheric CO2 content and due to interactive vegetation are shown to be at least of the same order of magnitude as differences between the two completely different models, demonstrating the importance of careful experimental design.” C. Kubatzki, M. Montoya, S. Rahmstorf, A. Ganopolski and M. Claussen, Climate Dynamics, Volume 16, Numbers 10-11 (2000), 799-814, DOI: 10.1007/s003820000078. [Full text]
Substantial contribution to sea-level rise during the last interglacial from the Greenland ice sheet – Cuffey & Marshall (2000) “During the last interglacial period (the Eemian), global sea level was at least three metres, and probably more than five metres, higher than at present. Complete melting of either the West Antarctic ice sheet or the Greenland ice sheet would today raise sea levels by 6–7 metres. But the high sea levels during the last interglacial period have been proposed to result mainly from disintegration of the West Antarctic ice sheet, with model studies attributing only 1–2 m of sea-level rise to meltwater from Greenland. This result was considered consistent with ice core evidence4, although earlier work had suggested a much reduced Greenland ice sheet during the last interglacial period6. Here we reconsider the Eemian evolution of the Greenland ice sheet by combining numerical modelling with insights obtained from recent central Greenland ice-core analyses. Our results suggest that the Greenland ice sheet was considerably smaller and steeper during the Eemian, and plausibly contributed 4–5.5 m to the sea-level highstand during that period. We conclude that the high sea level during the last interglacial period most probably included a large contribution from Greenland meltwater and therefore should not be interpreted as evidence for a significant reduction of the West Antarctic ice sheet.” Kurt M. Cuffey & Shawn J. Marshall, Nature 404, 591-594 (6 April 2000) | doi:10.1038/35007053. [Full text]
Multiproxy climate reconstructions for the Eemian and Early Weichselian – Aalbersberg & Litt (1998) “Palaeobotanical, coleopteran and periglacial data from 106 sites across northwestern Europe have been analysed in order to reconstruct palaeoclimatic conditions during the Eemian and Early Weichselian. Three time slices in the Eemian and four in the Early Weichselian have been considered. In the Pinus–Quercetum mixtum–Corylus phase of the Eemian, summer temperatures were probably at their highest and the botanic evidence suggests a southeast to northwest gradient for both the warmest and coldest month. Coleoptera indicate that the summers in southern England were several degrees warmer than those of present day. The climate during theCarpinus–Picea phase was uniform and oceanic without obvious gradients. In the final time slice of the Eemian, the Pinus–Picea–Abies phase, temperatures of the warmest month seem to drop slightly with some indication of a shift towards a more boreal and suboceanic climate. The reconstruction of the palaeoclimate in the Herning Stadial and Rederstall Stadial is hampered by the limited number of sites, but botanical evidence suggests a gradient in temperature of the coldest month from east to west. Coleoptera from the Herning Stadial in central England and eastern Germany suggest similarly cold and continental climates. During the Brørup Interstadial and the Odderade Interstadial the botanical evidence suggests that the minimum mean July temperatures rose to 15–16°C but during the coldest month these temperatures show a gradient between −13°C in the east and −5°C in the west.” Gerard Aalbersberg, Thomas Litt, Journal of Quaternary Science, Special Issue: Palaeoclimate of the last Interglacial- Glacial Cycle in Western and Central Europe, Volume 13, Issue 5, pages 367–390, September/October 1998, DOI: 10.1002/(SICI)1099-1417(1998090)13:53.0.CO;2-I..
An analysis of Eemian climate in Western and Central Europe – Zagwijn (1996) “On the basis of 31 pollen diagrams and additional data for botanical macrofossils an analysis is made of the Last Interglacial (Eemian) climatic history in Western and Central Europe. The main tool for this analysis is the climatic indicator species method. Only selected woody species are used for the quantification of data. Partial climatic range diagrams are presented for: Abies alba, Acer monspessulanum, Acer tataricum, Buxus sempervirens, Tilia tomentosa. The problem of time correlation and pollen zonation of the Eemian is discussed. The climatic analysis itself is based on an improved version of the indicator species method. In this version not every site is analysed for its climatic values. Instead maps and tables on the migrational history of Hedera, Ilex, Buxus, Abies and species of Acer, Tilia and Abies are the basis for climatic maps showing respectively January and July isotherms for the periods of the Corylus zone (E4a) and the Carpinus zone (E5). It is concluded that mean January temperatures were as much as 3°C higher at Amsterdam (The Netherlands), than at present, and mean temperatures in July were 2°C higher. However, the thermal maximum in winter was later (zone E5) than the summer thermal maximum (zone E4a). Winter temperatures changed parallel to rise and fall of global sea-level. Precipitation changes are more difficult to estimate. In the first part of the Eemian precipitation must have been relatively low, but from zone E4b onward it increased to higher values, reaching 800 mm and probably substantially more in zones E5 and E6. Hence the Eemian climate was in its beginning relatively more contintental, and later (from E4b onward) more oceanic. However, as compared with the Holocene, the Eemian climate was, generally speaking, more oceanic.” W.H. Zagwijn, Quaternary Science Reviews, Volume 15, Issues 5–6, 1996, Pages 451–469, http://dx.doi.org/10.1016/0277-3791(96)00011-X.
Rapid changes in ocean circulation and heat flux in the Nordic seas during the last interglacial period – Fronval & Jansen (1996) “THE apparent similarity of climate variability in the North Atlantic region in the last interglacial period and the present interglacial (Holocene) has recently been challenged by the rapid oscillations in climate conditions indicated by some marine and terrestrial climate records8–10 for the last interglacial. Ocean circulation in the northern North Atlantic seems to be intimately coupled to the processes of climate change on various time-scales, so that climate variability—and the associated mechanisms of change—should be well recorded by sediments from these high latitudes. Previous studies in this region have indeed indicated an apparently less stable last-interglacial climate than at middle latitudes of the North Atlantic Ocean4. Here we present detailed records from marine sediments in the Nordic seas of oceanographic conditions during the last interglacial. The records show three large sea surface temperature fluctuations, a weakening of the east–west sea surface temperature gradient with time, and changes in deep-water properties. In contrast, similar analyses of a core from the same region indicate that sea surface temperature during the Holocene has been relatively stable. Our data—along with those from the Labrador Sea7—indicate rapid changes in ocean circulation and oceanic heat fluxes at high northern latitudes during the last interglacial, which may have been associated with marked temperature changes on adjacent continents.” Torben Fronval & Eystein Jansen, Nature 383, 806 – 810 (31 October 1996); doi:10.1038/383806a0.
The Last Interglaciation in Arctic and Subarctic Regions: Time Frame, Structure, and Duration: Selected Papers from a LIGA Symposium Held in Saint-Michel des Saints, Quebec, Canada, May 4-7, 1993 – Lauritzen & Anderson (1995) Selected papers in question are included to this issue of journal Quaternary Research (including Brigham-Grette & Hopkins paper presented below). Stein-Erik Lauritzen, Patricia M. Anderson, Quaternary Research, Volume 43, Issue 2, March 1995, Pages 115–116.
Emergent Marine Record and Paleoclimate of the Last Interglaciation along the Northwest Alaskan Coast – Brigham-Grette & Hopkins (1995) “The last interglacial high sea-level stand, the Pelukian transgression of isotope substage 5e, is recorded along the western and northern coasts of Alaska by discontinuous but clearly traceable marine terraces and coastal landforms up to about 10 m altitude. The stratigraphy indicates that sea level reached this altitude only once during the last interglacial cycle. From the type area at Nome, to St. Lawrence Island in the Bering Sea, to the eastern limit of the Beaufort Sea, Pelukian deposits contain extralimital faunas indicating that coastal waters were warmer than present. Amino acid ratios in molluscs from these deposits decrease to the north toward Barrow, consistent with the modern regional temperature gradient. Fossil assemblages at Nome and St. Lawrence Island suggest that the winter sea-ice limit was north of Bering Strait, at least 800 km north of its present position, and the Bering Sea was perennially ice-free. Microfauna in Pelukian sediments recovered from boreholes indicate that Atlantic water may have been present on the shallow Beaufort Shelf, suggesting that the Arctic Ocean was not stratified and the Arctic sea-ice cover was not perennial for some period. In coastal regions of western Alaska, spruce woodlands extended westward beyond their modern range and in northern Alaska, on the Arctic Coastal Plain, spruce groves may have entered the upper Colville River basin. The Flaxman Member of the Gubik Formation on the Alaskan Arctic Coastal Plain was deposited during marine isotope substage 5a and records the breakup of an intra-stage 5 ice sheet over northwestern Keewatin.” Julie Brigham-Grette, David M. Hopkins, Quaternary Research, Volume 43, Issue 2, March 1995, Pages 159–173, http://dx.doi.org/10.1006/qres.1995.1017. [FULL TEXT]
High-resolution climate records from the North Atlantic during the last interglacial – McManus et al. (1994) “THE two deep ice cores recovered by the GRIP and GISP2 projects at Summit, Greenland, agree in detail over the past 100,000 years and demonstrate dramatic climate variability in the North Atlantic region during the last glacial, before the current period of Holocene stability. This glacial climate instability has subsequently been documented in the marine sedimentary record of surface-ocean conditions in the North Atlantic. Before 100 kyr ago the two ice core records are discrepant, however, casting doubt on whether the oxygen isotope fluctuations during the last interglacial (Eemian) seen in the GRIP core represent a true climate signal. Here we present high-resolution records of foraminiferal assemblages and ice-rafted detritus from two North Atlantic cores for the interval 65 kyr to 135 kyr ago, extending the surface-ocean record back to the Eemian. The correlation between our records and the Greenland ice-core records is good throughout the period in which the two ice cores agree, suggesting a regionally coherent climate response. During the Eemian, our marine records show a more stable climate than that implied by the GRIP ice core, suggesting that localized phenomena may be responsible for the variability in the latter record during the Eemian.” J. F. McManus, G. C. Bond, W. S. Broecker, S. Johnsen, L. Labeyrie & S. Higgins, Nature 371, 326 – 329 (22 September 1994); doi:10.1038/371326a0. [Full text]
Constraints on the age and duration of the last interglacial period and on sea-level variations – Lambeck & Nakada (1992) “The relation between height and age of shorelines formed during the last interglacial period, as revealed by coral reefs, cannot be related directly to changes in ocean volume because of the effect of isostatic uplift in response to changes in ice-sheet loading. Sea-level changes at sites near the melting ice sheet, such as Bermuda and the Caribbean islands, differ from those along the Australian margin. Modelling of these differences constrains the times of onset and termination of the last interglacial, which are at variance with those deduced from oxygen-isotope studies of deep-sea cores.” Kurt Lambeck & Masao Nakada, Nature 357, 125 – 128 (14 May 1992); doi:10.1038/357125a0.