Large variations in Holocene solar activity: Constraints from10Be in the Greenland Ice Core Project ice core

AbstractWe performed microscopic observations and a statistical study of the number, size and shape distribution of clathrates in the GRIP (Greenland Ice Core Project) deep ice core, using 185 samples from a depth range of 1016–3014 m, spanning a period of 6 to >110 ka BP and encompassing the Holocene, Wisconsin and Eemian periods. The number concentration of the clathrates varied considerably with climatic changes. It was possible to detect the rapid climatic oscillations in the last glacial between 13 and 110 ka BP, the Dansgaard–Oeschger cycles, in the number-concentration profile of clathrates. The mean volume of clathrates is less clearly influenced by climatic factors, with a tendency towards greater volumes in warmer periods, but also a growth of clathrates with depth could be detected. This growth rate was calculated to be 3.1 × 10-12 cm3 a-1. The amount of gases captured in the clathrates is estimated to be significantly smaller than the total amount of air determined by gas-concentration measurements. This points to diffusion processes of atmospheric gases within the ice matrix.

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Tree-ring radiocarbon reveals reduced solar activity during Younger Dryas cooling

10.5194/egusphere-egu2020-11654 ◽

2020 ◽

Cited By ~ 2

Author(s):

Adam Sookdeo ◽

Bernd Kromer ◽

Florian Adolphi ◽

Jürg Beer ◽

Nicolas Brehm ◽

...

Keyword(s):

Solar Activity ◽

Tree Ring ◽

North Atlantic ◽

Little Ice Age ◽

Ice Core ◽

Younger Dryas ◽

Ice Age ◽

The North ◽

Long Duration ◽

Clear Sign

The Younger Dryas stadial (YD) was a return to glacial-like conditions in the North Atlantic region that interrupted deglacial warming around 12900 cal BP (before 1950 AD). Terrestrial and marine records suggest this event was initiated by the interruption of deep-water formation arising from North American freshwater runoff, but the causes of the millennia-long duration remain unclear. To investigate the solar activity, a possible YD driver, we exploit the cosmic production signals of tree-ring radiocarbon (14C) and ice-core beryllium-10 (10Be). Here we present the highest temporally resolved dataset of 14C measurements (n = 1558) derived from European tree rings that have been accurately extended back to 14226 cal BP (&#177;8, 2-&#963;), allowing precise alignment of ice-core records across this period. We identify a substantial increase in 14C and 10Be production starting at 12780 cal BP is comparable in magnitude to the historic Little Ice Age, being a clear sign of grand solar minima. We hypothesize the timing of the grand solar minima provides a significant amplifying factor leading to the harsh sustained glacial-like conditions seen in the YD.

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Surface accumulation in Northern Central Greenland during the last 300 years

Annals of Glaciology ◽

10.1017/aog.2020.30 ◽

2020 ◽

Vol 61 (81) ◽

pp. 214-224 ◽

Cited By ~ 2

Author(s):

Nanna B. Karlsson ◽

Sebastian Razik ◽

Maria Hörhold ◽

Anna Winter ◽

Daniel Steinhage ◽

...

Keyword(s):

Large Scale ◽

Climate Models ◽

Regional Climate ◽

Ice Core ◽

Regional Climate Models ◽

Radar Data ◽

Accumulation Rates ◽

Ground Penetrating ◽

Core Project ◽

North Greenland

AbstractThe internal stratigraphy of snow and ice as imaged by ground-penetrating radar may serve as a source of information on past accumulation. This study presents results from two ground-based radar surveys conducted in Greenland in 2007 and 2015, respectively. The first survey was conducted during the traverse from the ice-core station NGRIP (North Greenland Ice Core Project) to the ice-core station NEEM (North Greenland Eemian Ice Drilling). The second survey was carried out during the traverse from NEEM to the ice-core station EGRIP (East Greenland Ice Core Project) and then onwards to Summit Station. The total length of the radar profiles is 1427 km. From the radar data, we retrieve the large-scale spatial variation of the accumulation rates in the interior of the ice sheet. The accumulation rates range from 0.11 to 0.26 m a−1 ice equivalent with the lowest values found in the northeastern sector towards EGRIP. We find no evidence of temporal or spatial changes in accumulation rates when comparing the 150-year average accumulation rates with the 321-year average accumulation rates. Comparisons with regional climate models reveal that the models underestimate accumulation rates by up to 35% in northeastern Greenland. Our results serve as a robust baseline to detect present changes in either surface accumulation rates or patterns.

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Environmental records from polar ice cores

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1990.0026 ◽

1990 ◽

Vol 330 (1615) ◽

pp. 459-462 ◽

Cited By ~ 1

Keyword(s):

Solar Activity ◽

Ice Core ◽

Ice Cores ◽

Polar Ice ◽

Cosmogenic Isotope ◽

Wide Range ◽

Recent Part ◽

Ice Core Records

Polar ice cores provide a wide range of information on past atmospheric climate (temperature, precipitation) and environment (gas and aerosol concentrations). The dating can be very accurate for the more recent part of the records but accuracy decreases with depth and time. Measurements of cosmogenic isotope concentrations (such as 10 Be) provide information on palaeo-precipitation rates and particular events can be used to correlate ice core records. Besides these climatic applications, 10 Be concentration records in ice cores also contain information on solar activity changes.

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