Fires Support Biome Shifts in E Siberia? Interglacial Fire-Vegetation-Climate Feedbacks Reconstructed from MIS-11-Sediments of Lake El’gygytgyn

Abstract. Preliminary analyses of Lake El'gygytgyn sediment indicate a wide range of ecosystem responses to warmer than present climates. While palynological work describing all interglacial vegetation is ongoing, sufficient data exist to compare recent warm events (the postglacial thermal maximum, PGTM, and marine isotope stage, MIS5) with "super" interglaciations (MIS11, MIS31). Palynological assemblages associated with these climatic optima suggest two types of vegetation responses: one dominated by deciduous taxa (PGTM, MIS5) and the second by evergreen conifers (MIS11, MIS31). MIS11 forests show a similarity to modern Picea–Larix–Betula–Alnus forests of Siberia. While dark coniferous forest also characterizes MIS31, the pollen taxa show an affinity to the boreal forest of the lower Amur valley (southern Russian Far East). Despite vegetation differences during these thermal maxima, all glacial–interglacial transitions are alike, being dominated by deciduous woody taxa. Initially Betula shrub tundra established and was replaced by tundra with tree-sized shrubs (PGTM), Betula woodland (MIS5), or Betula–Larix (MIS11, MIS31) forest. The consistent occurrence of deciduous forest and/or high shrub tundra before the incidence of maximum warmth underscores the importance of this biome for modeling efforts. The El'gygytgyn data also suggest a possible elimination or massive reduction of Arctic plant communities under extreme warm-earth scenarios.

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Quantitative and qualitative constraints on hind-casting the formation of multiyear lake-ice covers at Lake El'gygytgyn

Climate of the Past ◽

10.5194/cp-9-1253-2013 ◽

2013 ◽

Vol 9 (3) ◽

pp. 1253-1269 ◽

Cited By ~ 15

Author(s):

M. Nolan

Keyword(s):

Water Exchange ◽

Sediment Cores ◽

Ice Cover ◽

Lake Ice ◽

Ice Growth ◽

Temperature Reduction ◽

Air Temperatures ◽

Lake El’Gygytgyn ◽

Oxygen Conditions ◽

Multiyear Ice

Abstract. Analysis of the 3.6 Ma, 318 m long sediment core from Lake El'gygytgyn suggests that the lake was covered by ice for millennia at a time for much of its history and therefore this paper uses a suite of existing, simple, empirical degree-day models of lake-ice growth and decay to place quantitative constraints on air temperatures needed to maintain a permanent ice cover on the lake. We also provide an overview of the modern climatological and physical processes that relate to lake-ice growth and decay as a basis for evaluating past climate and environmental conditions. Our modeling results indicate that modern annual mean air temperature would only have to be reduced by 3.3 °C ± 0.9 °C to initiate a multiyear ice cover and a temperature reduction of at least 5.5 °C ± 1.0 °C is likely needed to completely eliminate direct air–water exchange of oxygen, conditions that have been inferred at Lake El'gygytgyn from the analysis of sediment cores. Once formed, a temperature reduction of only 1–3 °C relative to modern may be all that is required to maintain multiyear ice. We also found that formation of multiyear ice covers requires that positive degree days are reduced by about half the modern mean, from about +608 to +322. A multiyear ice cover can persist even with summer temperatures sufficient for a two-month long thawing period, including a month above +4 °C. Thus, it is likely that many summer biological processes and some lake-water warming and mixing may still occur beneath multiyear ice-covers even if air–water exchange of oxygen is severely restricted.

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The HadGEM2 family of Met Office Unified Model climate configurations

Geoscientific Model Development ◽

10.5194/gmd-4-723-2011 ◽

2011 ◽

Vol 4 (3) ◽

pp. 723-757 ◽

Cited By ~ 532

Author(s):

◽

N. Bellouin ◽

W. J. Collins ◽

I. D. Culverwell ◽

P. R. Halloran ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Specific Model ◽

Unified Model ◽

Sea Surface ◽

Climate Feedbacks ◽

Vertical Extension ◽

Overall Performance ◽

Tropical Sea ◽

Different Levels ◽

Model Family

Abstract. We describe the HadGEM2 family of climate configurations of the Met Office Unified Model, MetUM. The concept of a model "family" comprises a range of specific model configurations incorporating different levels of complexity but with a common physical framework. The HadGEM2 family of configurations includes atmosphere and ocean components, with and without a vertical extension to include a well-resolved stratosphere, and an Earth-System (ES) component which includes dynamic vegetation, ocean biology and atmospheric chemistry. The HadGEM2 physical model includes improvements designed to address specific systematic errors encountered in the previous climate configuration, HadGEM1, namely Northern Hemisphere continental temperature biases and tropical sea surface temperature biases and poor variability. Targeting these biases was crucial in order that the ES configuration could represent important biogeochemical climate feedbacks. Detailed descriptions and evaluations of particular HadGEM2 family members are included in a number of other publications, and the discussion here is limited to a summary of the overall performance using a set of model metrics which compare the way in which the various configurations simulate present-day climate and its variability.

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Chronology of Lake El'gygytgyn sediments – a combined magnetostratigraphic, palaeoclimatic and orbital tuning study based on multi-parameter analyses

Climate of the Past ◽

10.5194/cp-9-2413-2013 ◽

2013 ◽

Vol 9 (6) ◽

pp. 2413-2432 ◽

Cited By ~ 44

Author(s):

N. R. Nowaczyk ◽

E. M. Haltia ◽

D. Ulbricht ◽

V. Wennrich ◽

M. A. Sauerbrey ◽

...

Keyword(s):

Global Climate ◽

Far East ◽

Climatic Conditions ◽

Sedimentation Rates ◽

Scientific Drilling ◽

Lake El’Gygytgyn ◽

Age Model ◽

Orbital Tuning ◽

Lake Floor ◽

The Impact

Abstract. A 318-metre-long sedimentary profile drilled by the International Continental Scientific Drilling Program (ICDP) at Site 5011-1 in Lake El'gygytgyn, Far East Russian Arctic, has been analysed for its sedimentologic response to global climate modes by chronostratigraphic methods. The 12 km wide lake is sited off-centre in an 18 km large crater that was created by the impact of a meteorite 3.58 Ma ago. Since then sediments have been continuously deposited. For establishing their chronology, major reversals of the earth's magnetic field provided initial tie points for the age model, confirming that the impact occurred in the earliest geomagnetic Gauss chron. Various stratigraphic parameters, reflecting redox conditions at the lake floor and climatic conditions in the catchment were tuned synchronously to Northern Hemisphere insolation variations and the marine oxygen isotope stack, respectively. Thus, a robust age model comprising more than 600 tie points could be defined. It could be shown that deposition of sediments in Lake El'gygytgyn occurred in concert with global climatic cycles. The upper ~160 m of sediments represent the past 3.3 Ma, equivalent to sedimentation rates of 4 to 5 cm ka−1, whereas the lower 160 m represent just the first 0.3 Ma after the impact, equivalent to sedimentation rates in the order of 45 cm ka−1. This study also provides orbitally tuned ages for a total of 8 tephras deposited in Lake El'gygytgyn.

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Carbon cycle–climate feedbacks

Ecological Climatology ◽

10.1017/cbo9780511805530.030 ◽

2013 ◽

pp. 489-519

Author(s):

Gordon B. Bonan

Keyword(s):

Carbon Cycle ◽

Climate Feedbacks

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Amplified bioproductivity during Transition IV (332 000–342 000 yr ago): evidence from the geochemical record of Lake El'gygytgyn

Climate of the Past ◽

10.5194/cp-9-679-2013 ◽

2013 ◽

Vol 9 (2) ◽

pp. 679-686 ◽

Cited By ~ 8

Author(s):

L. Cunningham ◽

H. Vogel ◽

V. Wennrich ◽

O. Juschus ◽

N. Nowaczyk ◽

...

Keyword(s):

Sharp Increase ◽

Biogenic Silica ◽

Ice Cores ◽

Climatic Conditions ◽

The Arctic ◽

Significant Shift ◽

Geochemical Parameters ◽

Lake El’Gygytgyn ◽

Arctic Russia

Abstract. To date, terrestrial archives of long-term climatic change within the Arctic have widely been restricted to ice cores from Greenland and, more recently, sediments from Lake El'gygytgyn in northeast Arctic Russia. Sediments from this lake contain a paleoclimate record of glacial-interglacial cycles during the last three million years. Low-resolution studies at this lake have suggested that changes observed during Transition IV (the transition from marine isotope stage (MIS) 10 to MIS 9) are of greater amplitude than any observed since. In this study, geochemical parameters are used to infer past climatic conditions thus providing the first high-resolution analyses of Transition IV from a terrestrial Arctic setting. These results demonstrate that a significant shift in climate was subsequently followed by a rapid increase in biogenic silica (BSi) production. Following this sharp increase, bioproductivity remained high, but variable, for over a thousand years. This study reveals differences in the timing and magnitude of change within the ratio of silica to titanium (Si/Ti) and BSi records that would not be apparent in lower resolution studies. This has significant implications for the increasingly common use of Si/Ti data as an alternative to traditional BSi measurements.

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