https://notendur.hi.is/oi/PDF%20reprints/Svendsen%20et%20al%20-%20Late%20Quaternary%20ice%20sheet%20history%20of%20northern%20Eurasia.pdf

Late quaternary ice sheet history of northern Eurasia

The oscillations between glacial and interglacial climate conditions over the past three million years have been characterized by a transfer of immense amounts of water between two of its largest reservoirs on Earth -- the ice sheets and the oceans. Since the latest of these oscillations, the Last Glacial Maximum (between about 30,000 and 19,000 years ago), approximately 50 million cubic kilometres of ice has melted from the land-based ice sheets, raising global sea level by approximately 130 metres. Such rapid changes in sea level are part of a complex pattern of interactions between the atmosphere, oceans, ice sheets and solid earth, all of which have different response timescales. The trigger for the sea-level fluctuations most probably lies with changes in insolation, caused by astronomical forcing, but internal feedback cycles complicate the simple model of causes and effects.

Links between climate and sea levels for the past three million years

We present a new time-slice reconstruction of the Eurasian ice sheets (British–Irish, Svalbard–Barents–Kara Seas and Scandinavian) documenting the spatial evolution of these interconnected ice sheets every 1000 years from 25 to 10 ka, and at four selected time periods back to 40 ka. The time-slice maps of ice-sheet extent are based on a new Geographical Information System (GIS) database, where we have collected published numerical dates constraining the timing of ice-sheet advance and retreat, and additionally geomorphological and geological evidence contained within the existing literature. We integrate all uncertainty estimates into three ice-margin lines for each time-slice; a most-credible line, derived from our assessment of all available evidence, with bounding maximum and minimum limits allowed by existing data. This approach was motivated by the demands of glaciological, isostatic and climate modelling and to clearly display limitations in knowledge. The timing of advance and retreat were both remarkably spatially variable across the ice-sheet area. According to our compilation the westernmost limit along the British–Irish and Norwegian continental shelf was reached up to 7000 years earlier (at c. 27–26 ka) than the eastern limit on the Russian Plain (at c. 20–19 ka). The Eurasian ice sheet complex as a whole attained its maximum extent (5.5 Mkm2) and volume (~24 m Sea Level Equivalent) at c. 21 ka. Our continental-scale approach highlights instances of conflicting evidence and gaps in the ice-sheet chronology where uncertainties remain large and should be a focus for future research. Largest uncertainties coincide with locations presently below sea level and where contradicting evidence exists. This first version of the database and time-slices (DATED-1) has a census date of 1 January 2013 and both are available to download via the Bjerknes Climate Data Centre and PANGAEA (www.bcdc.no; http://doi.pangaea.de/10.1594/PANGAEA.848117).

The last Eurasian ice sheets - a chronological database and time-slice reconstruction, DATED-1

Deglaciation of Fennoscandia

https://notendur.hi.is/~oi/AG-326%202006%20readings/Scandinavia%20and%20White%20Sea%20area/Boulton%20et%20al%202001.pdf

Palaeoglaciology of an ice sheet through a glacial cycle: the European ice sheet through the Weichselian

The Last Interglacial-Glacial cycle in NE Fennoscandia: a nearly continuous record from Sokli (Finnish Lapland)

A Younger Dryas Icecap in the Equatorial Andes

The onset of glaciations in the Colombian Andes as recorded by the start of glaciofluvial sedimentation in the inter-montane Bogota basin is dated near the Gauss/Matuyama polarity reversal at 2.6 Ma; episodes of increased glacial activity occurred since ca. 0.8 Ma. Moraines and till beds in the higher parts of the Andes record a series of glacier fluctuations of Late Quaternary age. Radiocarbon dates of organic-rich sediments and palaeosols found associated with glacial landforms/deposits in mountain ranges exceeding 3600 m altitude in the Eastern Cordillera, in combination with evidence provided by the radiocarbon-dated palaeosol sequence in the region, place glacial events between probably 43 ka and 38 ka, 36 to 31 ka, 23.5 to 19.5 ka, 18.0 to 15.5 ka 13.5 to 12.5 ka, and most probably 11 to 10 ka (radiocarbon years BP). Independent chronologies for the glacial and palynological records of the Eastern Cordillera suggest a close match between stadials characterised by low upper Andean forest limits and glacier advances in the surrounding high-mountain ranges. Major glacier advances during the Middle Weichselian seem to have responded to cool and humid climatic conditions. The Late Weichselian Glacial Maximum (LGM) is recorded as a two-fold glaciation maximum just before 19.5 and 15.5 ka, with glaciers advancing some 1200 to 1100 m below their present limits; during the cooling events, the forest limit was depressed by 1100 to 900 m, implying a drop in mean annual temperature of ca. 8 to 6 °C, respectively. Interstadial conditions prevailed around 18 ka, when temperatures rose considerably to values up to 4 °C higher than during the preceding and following stadial periods. Mountain ranges below 4000 m altitude were deglaciated at ca. 12.5 ka following a Late-glacial advance of cirque glaciers. Younger Dryas cooling is well-registered in the palynological record; glaciers in the highest parts of the Andes seem to have responded to the cooling by extending to elevations some 700 m lower than at present. The glacial record registers a high climatic variability in the northern Tropical Andes during the Late Quaternary period.

Karin F. Helmens

Papers

The Last Interglacial-Glacial cycle in NE Fennoscandia: a nearly continuous record from Sokli (Finnish Lapland)

A Younger Dryas Icecap in the Equatorial Andes

The Quaternary glacial record of the Colombian Andes