Glacier extent and climate in the Maritime Alps during the Younger Dryas

Matteo Spagnolo (Corresponding Author), Adriano Ribolini

Research output: Contribution to journalArticle

Abstract

This study focuses on an Egesen-stadial moraine located at 1906-1920 m asl in the NE Maritime Alps, Europe. Three moraine boulders are dated, via cosmogenic isotope analyses, to 12,490 ± 1120, 12,260 ± 1220 and 13,840 ± 1240 yr, an age compatible with the Younger Dryas cooling event. The reconstructed glacier that deposited the moraine has an equilibrium line altitude of 2349 ± 5 m asl, calculated with an Accumulation Area Balance Ratio of 1.6. The result is very similar to the equilibrium line altitude of another reconstructed glacier that deposited a moraine also dated to Younger Dryas, in the SW Maritime Alps. The similarity suggests comparable climatic conditions across the region during the cooling event. The Younger Dryas palaeoprecipitation is 1549 ±26 mm/yr, calculated using the empirical law that links precipitation and temperature at a glacier equilibrium line altitude, with palaeotemperatures obtained from nearby palynological and chironomids studies. The palaeoprecipitation is similar to the present, thus indicating non-arid conditions during the Younger Dryas. This is probably due to the Maritime Alps peculiar position, at the crossroads between air masses from the Mediterranean and the North Atlantic, the latter displaced by the southward migration of the polar front. The equilibrium line altitude interval defined by the two reconstructed glaciers, is used to model the extent of another 66 potential Younger Dryas glaciersin the region. Each modelled glacier is reconstructed by iteratively changing the position of its front until the reconstructed glacier has an ELA that falls within the interval. The result, which is checked against geomorphological evidence, shows that glaciers covered 83.74 km2 during the Younger Dryas, with a volume of 5.39 km3. All valley heads were occupied by ice, except for the Maddalena/Larche Pass (1999 m asl), an ideal site for future archaeological, palaeoecological and palaeozoological studies.
Original languageEnglish
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Publication statusAccepted/In press - 4 Oct 2019

Fingerprint

maritime climate
Younger Dryas
glaciers
glacier
equilibrium line
moraine
climate
cooling
polar front
paleotemperature
Chironomidae
air mass
isotopes
ice
valleys
isotope
valley
air

Keywords

  • Younger Dryas
  • glacier reconstruction
  • equilibrium line altitude
  • palaeoclimate
  • cosmogenic dates
  • Maritime Alps

Cite this

@article{009357ad67aa4b5ca337aebb14db09d8,
title = "Glacier extent and climate in the Maritime Alps during the Younger Dryas",
abstract = "This study focuses on an Egesen-stadial moraine located at 1906-1920 m asl in the NE Maritime Alps, Europe. Three moraine boulders are dated, via cosmogenic isotope analyses, to 12,490 ± 1120, 12,260 ± 1220 and 13,840 ± 1240 yr, an age compatible with the Younger Dryas cooling event. The reconstructed glacier that deposited the moraine has an equilibrium line altitude of 2349 ± 5 m asl, calculated with an Accumulation Area Balance Ratio of 1.6. The result is very similar to the equilibrium line altitude of another reconstructed glacier that deposited a moraine also dated to Younger Dryas, in the SW Maritime Alps. The similarity suggests comparable climatic conditions across the region during the cooling event. The Younger Dryas palaeoprecipitation is 1549 ±26 mm/yr, calculated using the empirical law that links precipitation and temperature at a glacier equilibrium line altitude, with palaeotemperatures obtained from nearby palynological and chironomids studies. The palaeoprecipitation is similar to the present, thus indicating non-arid conditions during the Younger Dryas. This is probably due to the Maritime Alps peculiar position, at the crossroads between air masses from the Mediterranean and the North Atlantic, the latter displaced by the southward migration of the polar front. The equilibrium line altitude interval defined by the two reconstructed glaciers, is used to model the extent of another 66 potential Younger Dryas glaciersin the region. Each modelled glacier is reconstructed by iteratively changing the position of its front until the reconstructed glacier has an ELA that falls within the interval. The result, which is checked against geomorphological evidence, shows that glaciers covered 83.74 km2 during the Younger Dryas, with a volume of 5.39 km3. All valley heads were occupied by ice, except for the Maddalena/Larche Pass (1999 m asl), an ideal site for future archaeological, palaeoecological and palaeozoological studies.",
keywords = "Younger Dryas, glacier reconstruction, equilibrium line altitude, palaeoclimate, cosmogenic dates, Maritime Alps",
author = "Matteo Spagnolo and Adriano Ribolini",
note = "We would like to acknowledge: Prof. Rea and Dr Pellitero for fruitful discussions on various aspects of this work, and in particular on the use of glacier reconstruction and ELA GIS tools and extraction of climatic variables at a glacier ELA; Dr Ortu for kindly providing easy access to pollen data and for discussions on the climate of the Younger Dryas across the Alps; Prof. Edwards for discussions on pollen analyses; and Prof. Federici, for inspiring glaciological research in this beautiful region. The constructive and useful feedback provided by Dr Monegato and an anonymous reviewer is greatly appreciated. L. Cignoni is thanked for reviewing the English. MS acknowledges support from NERC (CIAF 9092.1010).",
year = "2019",
month = "10",
day = "4",
language = "English",
journal = "Palaeogeography Palaeoclimatology Palaeoecology",
issn = "0031-0182",
publisher = "Elsevier",

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TY - JOUR

T1 - Glacier extent and climate in the Maritime Alps during the Younger Dryas

AU - Spagnolo, Matteo

AU - Ribolini, Adriano

N1 - We would like to acknowledge: Prof. Rea and Dr Pellitero for fruitful discussions on various aspects of this work, and in particular on the use of glacier reconstruction and ELA GIS tools and extraction of climatic variables at a glacier ELA; Dr Ortu for kindly providing easy access to pollen data and for discussions on the climate of the Younger Dryas across the Alps; Prof. Edwards for discussions on pollen analyses; and Prof. Federici, for inspiring glaciological research in this beautiful region. The constructive and useful feedback provided by Dr Monegato and an anonymous reviewer is greatly appreciated. L. Cignoni is thanked for reviewing the English. MS acknowledges support from NERC (CIAF 9092.1010).

PY - 2019/10/4

Y1 - 2019/10/4

N2 - This study focuses on an Egesen-stadial moraine located at 1906-1920 m asl in the NE Maritime Alps, Europe. Three moraine boulders are dated, via cosmogenic isotope analyses, to 12,490 ± 1120, 12,260 ± 1220 and 13,840 ± 1240 yr, an age compatible with the Younger Dryas cooling event. The reconstructed glacier that deposited the moraine has an equilibrium line altitude of 2349 ± 5 m asl, calculated with an Accumulation Area Balance Ratio of 1.6. The result is very similar to the equilibrium line altitude of another reconstructed glacier that deposited a moraine also dated to Younger Dryas, in the SW Maritime Alps. The similarity suggests comparable climatic conditions across the region during the cooling event. The Younger Dryas palaeoprecipitation is 1549 ±26 mm/yr, calculated using the empirical law that links precipitation and temperature at a glacier equilibrium line altitude, with palaeotemperatures obtained from nearby palynological and chironomids studies. The palaeoprecipitation is similar to the present, thus indicating non-arid conditions during the Younger Dryas. This is probably due to the Maritime Alps peculiar position, at the crossroads between air masses from the Mediterranean and the North Atlantic, the latter displaced by the southward migration of the polar front. The equilibrium line altitude interval defined by the two reconstructed glaciers, is used to model the extent of another 66 potential Younger Dryas glaciersin the region. Each modelled glacier is reconstructed by iteratively changing the position of its front until the reconstructed glacier has an ELA that falls within the interval. The result, which is checked against geomorphological evidence, shows that glaciers covered 83.74 km2 during the Younger Dryas, with a volume of 5.39 km3. All valley heads were occupied by ice, except for the Maddalena/Larche Pass (1999 m asl), an ideal site for future archaeological, palaeoecological and palaeozoological studies.

AB - This study focuses on an Egesen-stadial moraine located at 1906-1920 m asl in the NE Maritime Alps, Europe. Three moraine boulders are dated, via cosmogenic isotope analyses, to 12,490 ± 1120, 12,260 ± 1220 and 13,840 ± 1240 yr, an age compatible with the Younger Dryas cooling event. The reconstructed glacier that deposited the moraine has an equilibrium line altitude of 2349 ± 5 m asl, calculated with an Accumulation Area Balance Ratio of 1.6. The result is very similar to the equilibrium line altitude of another reconstructed glacier that deposited a moraine also dated to Younger Dryas, in the SW Maritime Alps. The similarity suggests comparable climatic conditions across the region during the cooling event. The Younger Dryas palaeoprecipitation is 1549 ±26 mm/yr, calculated using the empirical law that links precipitation and temperature at a glacier equilibrium line altitude, with palaeotemperatures obtained from nearby palynological and chironomids studies. The palaeoprecipitation is similar to the present, thus indicating non-arid conditions during the Younger Dryas. This is probably due to the Maritime Alps peculiar position, at the crossroads between air masses from the Mediterranean and the North Atlantic, the latter displaced by the southward migration of the polar front. The equilibrium line altitude interval defined by the two reconstructed glaciers, is used to model the extent of another 66 potential Younger Dryas glaciersin the region. Each modelled glacier is reconstructed by iteratively changing the position of its front until the reconstructed glacier has an ELA that falls within the interval. The result, which is checked against geomorphological evidence, shows that glaciers covered 83.74 km2 during the Younger Dryas, with a volume of 5.39 km3. All valley heads were occupied by ice, except for the Maddalena/Larche Pass (1999 m asl), an ideal site for future archaeological, palaeoecological and palaeozoological studies.

KW - Younger Dryas

KW - glacier reconstruction

KW - equilibrium line altitude

KW - palaeoclimate

KW - cosmogenic dates

KW - Maritime Alps

M3 - Article

JO - Palaeogeography Palaeoclimatology Palaeoecology

JF - Palaeogeography Palaeoclimatology Palaeoecology

SN - 0031-0182

ER -