Palaeoclimatic and morphodynamic implications of Holocene boulder-dominated periglacial and paraglacial landforms in Rondane, South Norway

2021 ◽  
Author(s):  
Philipp Marr ◽  
Stefan Winkler ◽  
Svein Olaf Dahl ◽  
Jörg Löffler
Keyword(s):  
Slope Failure ◽  
Rock Slope ◽  
Control Point ◽  
Alluvial Fan ◽  
Age Dating ◽  
The Holocene ◽  
Holocene Thermal Maximum ◽  
Exposure Age ◽  
Thermal Maximum ◽  
Exposure Ages

<p>Periglacial, paraglacial and related boulder-dominated landforms constitute a valuable, but often unexplored source of palaeoclimatic and morphodynamic information. The timing of landform formation and stabilization can be linked to past cold climatic conditions which offers the possibility to reconstruct cold climatic periods. In this study, Schmidt-hammer exposure-age dating (SHD) was applied to a variety of boulder-dominated landforms (sorted stripes, blockfield, paraglacial alluvial fan, rock-slope failure) in Rondane, eastern South Norway for the first time. On the basis of an old and young control point a local calibration curve was established from which surface exposure ages of each landform were calculated. The investigation of formation, stabilization and age of the respective landforms permitted an assessment of Holocene climate variability in Rondane and its connectivity to landform evolution. The obtained SHD age estimates range from 11.15 ± 1.22 to 3.99 ± 1.52 ka which shows their general inactive and relict character. Most surface exposure ages of the sorted stripes cluster between 9.62 ± 1.36 and 9.01 ± 1.21 ka and appear to have stabilized towards the end of the ‘Erdalen Event’ or in the following warm period prior to ‘Finse Event’. The blockfield age with 8.40 ± 1.16 ka indicates landform stabilization during ‘Finse Event’, around the onset of the Holocene Thermal Maximum (~8.0–5.0 ka). The paraglacial alluvial fan with its four subsites shows age ranges from 8.51 ± 1.63 to 3.99 ± 1.52 ka. The old exposure age points to fan aggradation follow regional deglaciation due to paraglacial processes, whereas the younger ages can be explained by increasing precipitation during the onset neoglaciation at ~4.0 ka. Surface exposure age of the rock-slope failure with 7.39 ± 0.74 ka falls into a transitional climate period towards the Holocene Thermal Maximum (~8.0–5.0 ka). This indicates that climate-driven factors such as decreasing permafrost depth and/or increasing hydrological pressure negatively influence slope stability. Our obtained first surface exposure ages from boulder-dominated landforms in Rondane give important insights to better understand the palaeoclimatic variability in the Holocene.</p>

Schmidt-hammer exposure-age dating (SHD) performed on periglacial and related landforms in Opplendskedalen, Geirangerfjellet, Norway: Implications for mid- and late-Holocene climate variability

The Holocene ◽  
2018 ◽  
Vol 29 (1) ◽  
pp. 97-109 ◽  
Author(s):  
Philipp Marr ◽  
Stefan Winkler ◽  
Jörg Löffler
Keyword(s):  
Climate Variability ◽  
Late Holocene ◽  
Slope Failure ◽  
Rock Slope ◽  
Water Pressure ◽  
Age Dating ◽  
Schmidt Hammer ◽  
Holocene Climate ◽  
Valley Bottom ◽  
Exposure Age

Schmidt-hammer exposure-age dating (SHD) was applied to a variety of boulder-dominated periglacial landforms in an attempt to establish a local mid-/late-Holocene chronology for the Geirangerfjellet in South Norway. Landform ages were obtained by application of a local calibration curve for Schmidt hammer R-values based on young and old control points comprising fresh road cuts and a bedrock surface in proximity to the study area, respectively. The area was deglaciated ~11.5 ka ago according to independent age information. Investigation of age, formation and stabilization of the periglacial landforms and processes involved allowed assessment of the underlying Holocene climate variability and its relationship to landform evolution. Our SHD ages range from 7.47 ± 0.73 ka for glacially abraded bedrock at the valley bottom to 2.22 ± 0.49 ka for surface boulders of a rock-slope failure. All landforms shared negative skewness and largely have narrow tailed frequency distributions of their R-values. This points to either substantial reworking of the boulders within a landform or continuous debris supply. Our results show that most landforms stabilized during the Holocene Thermal Maximum (~8.0–5.0 ka). The findings do not support the hypothesis that rock-slope failures predominately occur shortly after local deglaciation. Instead, it appears that they cluster during warm periods due to climate-driven factors, for example, decreasing permafrost depth or increasing cleft-water pressure leading to slope instabilities. Periglacial boulder-dominated landforms in the western maritime fjord region seem to react sensitively to Holocene climate variability and may constitute valuable but to date mostly unexplored sources of palaeoclimatic information.

scholarly journals The Holocene thermal maximum in the Nordic Seas: the impact of Greenland Ice Sheet melt and other forcings in a coupled atmosphere–sea-ice–ocean model

2013 ◽  
Vol 9 (4) ◽  
pp. 1629-1643 ◽  
Author(s):  
M. Blaschek ◽  
H. Renssen
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Early Holocene ◽  
Surface Cooling ◽  
Holocene Climate ◽  
Nordic Seas ◽  
The Holocene ◽  
Holocene Thermal Maximum ◽  
Thermal Maximum ◽  
The Impact

Abstract. The relatively warm early Holocene climate in the Nordic Seas, known as the Holocene thermal maximum (HTM), is often associated with an orbitally forced summer insolation maximum at 10 ka BP. The spatial and temporal response recorded in proxy data in the North Atlantic and the Nordic Seas reveals a complex interaction of mechanisms active in the HTM. Previous studies have investigated the impact of the Laurentide Ice Sheet (LIS), as a remnant from the previous glacial period, altering climate conditions with a continuous supply of melt water to the Labrador Sea and adjacent seas and with a downwind cooling effect from the remnant LIS. In our present work we extend this approach by investigating the impact of the Greenland Ice Sheet (GIS) on the early Holocene climate and the HTM. Reconstructions suggest melt rates of 13 mSv for 9 ka BP, which result in our model in an ocean surface cooling of up to 2 K near Greenland. Reconstructed summer SST gradients agree best with our simulation including GIS melt, confirming that the impact of the early Holocene GIS is crucial for understanding the HTM characteristics in the Nordic Seas area. This implies that modern and near-future GIS melt can be expected to play an active role in the climate system in the centuries to come.

scholarly journals Quantifying soil carbon accumulation in Alaskan terrestrial ecosystems during the last 15 000 years

2016 ◽  
Vol 13 (22) ◽  
pp. 6305-6319 ◽  
Author(s):  
Sirui Wang ◽  
Qianlai Zhuang ◽  
Zicheng Yu
Keyword(s):  
20Th Century ◽  
Average Rate ◽  
Terrestrial Ecosystems ◽  
Carbon Accumulation ◽  
The Holocene ◽  
Holocene Thermal Maximum ◽  
Peat Core ◽  
Thermal Maximum ◽  
Soil Carbon Accumulation ◽  
Climate Cooling

Abstract. Northern high latitudes contain large amounts of soil organic carbon (SOC), of which Alaskan terrestrial ecosystems account for a substantial proportion. In this study, the SOC accumulation in Alaskan terrestrial ecosystems over the last 15 000 years was simulated using a process-based biogeochemistry model for both peatland and non-peatland ecosystems. Comparable with the previous estimates of 25–70 Pg C in peatland and 13–22 Pg C in non-peatland soils within 1 m depth in Alaska using peat-core data, our model estimated a total SOC of 36–63 Pg C at present, including 27–48 Pg C in peatland soils and 9–15 Pg C in non-peatland soils. Current vegetation stored 2.5–3.7 Pg C in Alaska, with 0.3–0.6 Pg C in peatlands and 2.2–3.1 Pg C in non-peatlands. The simulated average rate of peat C accumulation was 2.3 Tg C yr−1, with a peak value of 5.1 Tg C yr−1 during the Holocene Thermal Maximum (HTM) in the early Holocene, 4-fold higher than the average rate of 1.4 Tg C yr−1 over the rest of the Holocene. The SOC accumulation slowed down, or even ceased, during the neoglacial climate cooling after the mid-Holocene, but increased again in the 20th century. The model-estimated peat depths ranged from 1.1 to 2.7 m, similar to the field-based estimate of 2.29 m for the region. We found that the changes in vegetation and their distributions were the main factors in determining the spatial variations of SOC accumulation during different time periods. Warmer summer temperature and stronger radiation seasonality, along with higher precipitation in the HTM and the 20th century, might have resulted in the extensive peatland expansion and carbon accumulation.

scholarly journals Mid-Holocene Northern Hemisphere warming driven by Arctic amplification

2019 ◽  
Vol 5 (12) ◽  
pp. eaax8203 ◽  
Author(s):  
Hyo-Seok Park ◽  
Seong-Joong Kim ◽  
Andrew L. Stewart ◽  
Seok-Woo Son ◽  
Kyong-Hwan Seo
Keyword(s):  
Sea Ice ◽  
Northern Hemisphere ◽  
High Latitude ◽  
Climate Model ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Arctic Amplification ◽  
The Holocene ◽  
Holocene Thermal Maximum ◽  
Thermal Maximum

The Holocene thermal maximum was characterized by strong summer solar heating that substantially increased the summertime temperature relative to preindustrial climate. However, the summer warming was compensated by weaker winter insolation, and the annual mean temperature of the Holocene thermal maximum remains ambiguous. Using multimodel mid-Holocene simulations, we show that the annual mean Northern Hemisphere temperature is strongly correlated with the degree of Arctic amplification and sea ice loss. Additional model experiments show that the summer Arctic sea ice loss persists into winter and increases the mid- and high-latitude temperatures. These results are evaluated against four proxy datasets to verify that the annual mean northern high-latitude temperature during the mid-Holocene was warmer than the preindustrial climate, because of the seasonally rectified temperature increase driven by the Arctic amplification. This study offers a resolution to the “Holocene temperature conundrum”, a well-known discrepancy between paleo-proxies and climate model simulations of Holocene thermal maximum.

scholarly journals The Holocene thermal maximum in the Nordic Seas: the impact of Greenland Ice Sheet melt and other forcings in a coupled atmosphere-sea ice-ocean model

2012 ◽  
Vol 8 (5) ◽  
pp. 5263-5291 ◽  
Author(s):  
M. Blaschek ◽  
H. Renssen
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Early Holocene ◽  
Surface Cooling ◽  
Holocene Climate ◽  
Nordic Seas ◽  
The Holocene ◽  
Holocene Thermal Maximum ◽  
Thermal Maximum ◽  
The Impact

Abstract. The relatively warm early Holocene climate in the Nordic Seas, known as the Holocene Thermal Maximum (HTM), is often associated with an orbitally forced summer insolation maximum at 10 ka BP. The spatial and temporal response recorded in proxy data in the North Atlantic and the Nordic Seas reveal a complex interaction of mechanisms active in the HTM. Previous studies have investigated the impact of the Laurentide Ice Sheet (LIS), as a remnant from a previous glacial period, altering climate conditions with a continuous supply of melt water to the Labrador Sea and adjacent seas and with a downwind cooling effect from the remnant LIS. In our present work we extend this approach by investigating the impact of the Greenland Ice Sheet (GIS) on the early Holocene climate and the HTM. Reconstructions suggest melt rates of 13 mSv for 9 ka BP, which result in our model in a ocean surface cooling of up to 2 K near Greenland. Reconstructed summer SST gradients agree best with our simulation including GIS melt, confirming that the impact of early Holocene GIS is crucial for understanding the HTM characteristics in the Nordic Seas area. This implies that the modern and near-future GIS melt can be expected to play an active role in the climate system in the centuries to come.

Holocene alluvial fan evolution, Schmidt‐hammer exposure‐age dating and paraglacial debris floods in the SE Jostedalsbreen region, southern Norway

Boreas ◽  
2020 ◽  
Vol 49 (4) ◽  
pp. 886-902
Author(s):  
John A. Matthews ◽  
Lindsey J. McEwen ◽  
Geraint Owen ◽  
Sietse Los
Keyword(s):  
Alluvial Fan ◽  
Age Dating ◽  
Schmidt Hammer ◽  
Exposure Age ◽  
Southern Norway ◽  
Debris Floods

scholarly journals Holocene atmospheric iodine evolution over the North Atlantic

2019 ◽  
Vol 15 (6) ◽  
pp. 2019-2030 ◽  
Author(s):  
Juan Pablo Corella ◽  
Niccolo Maffezzoli ◽  
Carlos Alberto Cuevas ◽  
Paul Vallelonga ◽  
Andrea Spolaor ◽  
...  
Keyword(s):  
North Atlantic ◽  
Ice Core ◽  
First Record ◽  
Atmospheric Composition ◽  
The Holocene ◽  
Holocene Thermal Maximum ◽  
Ice Cap ◽  
The North ◽  
Thermal Maximum ◽  
The North Atlantic

Abstract. Atmospheric iodine chemistry has a large influence on the oxidizing capacity and associated radiative impacts in the troposphere. However, information on the evolution of past atmospheric iodine levels is restricted to the industrial period while its long-term natural variability remains unknown. The current levels of iodine in the atmosphere are controlled by anthropogenic ozone deposition to the ocean surface. Here, using high-resolution geochemical measurements from coastal eastern Greenland ReCAP (REnland ice CAP project) ice core, we report the first record of atmospheric iodine variability in the North Atlantic during the Holocene (i.e., the last 11 700 years). Surprisingly, our results reveal that the highest iodine concentrations in the record were found during the Holocene Thermal Maximum (HTM; ∼ 11 500–5500 years before-present). These high iodine levels could be driven by marine primary productivity resulting in an Early Holocene “biological iodine explosion”. The high and stable iodine levels during this past warm period are a useful observational constraint on projections of future changes in Arctic atmospheric composition and climate resulting from global warming.

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