scholarly journals Life and extinction of megafauna in the ice-age Arctic

2015 ◽  
Vol 112 (46) ◽  
pp. 14301-14306 ◽  
Author(s):  
Daniel H. Mann ◽  
Pamela Groves ◽  
Richard E. Reanier ◽  
Benjamin V. Gaglioti ◽  
Michael L. Kunz ◽  
...  
Keyword(s):  
Statistical Approach ◽  
Ice Age ◽  
The Arctic ◽  
North Slope ◽  
Long Distance ◽  
Geographic Ranges ◽  
Terminal Pleistocene ◽  
Last Ice Age ◽  
Characteristic Features

Understanding the population dynamics of megafauna that inhabited the mammoth steppe provides insights into the causes of extinctions during both the terminal Pleistocene and today. Our study area is Alaska's North Slope, a place where humans were rare when these extinctions occurred. After developing a statistical approach to remove the age artifacts caused by radiocarbon calibration from a large series of dated megafaunal bones, we compare the temporal patterns of bone abundance with climate records. Megafaunal abundance tracked ice age climate, peaking during transitions from cold to warm periods. These results suggest that a defining characteristic of the mammoth steppe was its temporal instability and imply that regional extinctions followed by population reestablishment from distant refugia were characteristic features of ice-age biogeography at high latitudes. It follows that long-distance dispersal was crucial for the long-term persistence of megafaunal species living in the Arctic. Such dispersal was only possible when their rapidly shifting range lands were geographically interconnected. The end of the last ice age was fatally unique because the geographic ranges of arctic megafauna became permanently fragmented after stable, interglacial climate engendered the spread of peatlands at the same time that rising sea level severed former dispersal routes.

scholarly journals Arctic Ocean stratification set by sea level and freshwater inputs since the last ice age

2021 ◽  
Author(s):  
Jesse R. Farmer ◽  
Daniel M. Sigman ◽  
Julie Granger ◽  
Ona M. Underwood ◽  
François Fripiat ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Surface Waters ◽  
Ice Age ◽  
The Arctic ◽  
Bering Strait ◽  
Central Arctic Ocean ◽  
Phytoplankton Productivity ◽  
Nitrate Consumption ◽  
Western Arctic ◽  
Last Ice Age

AbstractSalinity-driven density stratification of the upper Arctic Ocean isolates sea-ice cover and cold, nutrient-poor surface waters from underlying warmer, nutrient-rich waters. Recently, stratification has strengthened in the western Arctic but has weakened in the eastern Arctic; it is unknown if these trends will continue. Here we present foraminifera-bound nitrogen isotopes from Arctic Ocean sediments since 35,000 years ago to reconstruct past changes in nutrient sources and the degree of nutrient consumption in surface waters, the latter reflecting stratification. During the last ice age and early deglaciation, the Arctic was dominated by Atlantic-sourced nitrate and incomplete nitrate consumption, indicating weaker stratification. Starting at 11,000 years ago in the western Arctic, there is a clear isotopic signal of Pacific-sourced nitrate and complete nitrate consumption associated with the flooding of the Bering Strait. These changes reveal that the strong stratification of the western Arctic relies on low-salinity inflow through the Bering Strait. In the central Arctic, nitrate consumption was complete during the early Holocene, then declined after 5,000 years ago as summer insolation decreased. This sequence suggests that precipitation and riverine freshwater fluxes control the stratification of the central Arctic Ocean. Based on these findings, ongoing warming will cause strong stratification to expand into the central Arctic, slowing the nutrient supply to surface waters and thus limiting future phytoplankton productivity.

scholarly journals Long-period changes of the air temperature in Tatarstan and their forecast till the end of the 21st century

2019 ◽  
pp. 94-107
Author(s):  
Yuri P. Perevedentsev ◽  
Konstantin M. Shantalinskii ◽  
Boris G. Sherstukov ◽  
Alexander A. Nikolaev
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
21St Century ◽  
Ocean Surface ◽  
The Arctic ◽  
Long Distance ◽  
Climate Fluctuations ◽  
Long Period ◽  
The Earth

Long-term changes in air temperature on the territory of the Republic of Tatarstan in the 20th–21st centuries are considered. The periods of unambiguous changes in the surface air temperature are determined. It is established that the average winter temperature from the 1970s to 2017, increased in the Kazan region by more than 3 °C and the average summer temperature increased by about 2 °C over the same period. The contribution of global scale processes to the variability of the temperature of the Kazan region is shown: it was 37 % in winter, 23 % in summer. The correlation analysis of the anomalies of average annual air temperature in Kazan and the series of air temperature anomalies in each node over the continents, as well as the ocean surface temperature in each coordinate node on Earth for 1880 –2017, was performed. Long-distance communications were detected in the temperature field between Kazan and remote regions of the Earth. It is noted that long-period climate fluctuations in Kazan occur synchronously with fluctuations in the high latitudes of Asia and North America, with fluctuations in ocean surface temperature in the Arctic ocean, with fluctuations in air temperature in the Far East, and with fluctuations in ocean surface temperature in the Southern hemisphere in the Indian and Pacific oceans, as well as air temperature in southern Australia. It is suggested that there is a global mechanism that regulates long-term climate fluctuations throughout the Earth in the considered interval of 200 years of observations. According to the CMIP5 project, climatic scenarios were built for Kazan until the end of the 21st century.

Colonisation of Greenland by plants and animals after the last ice age: a review

Polar Record ◽  
1999 ◽  
Vol 35 (195) ◽  
pp. 323-336 ◽  
Author(s):  
Ole Bennike
Keyword(s):  
Endemic Species ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Age ◽  
Long Distance ◽  
Cold Adapted ◽  
Northwest Europe ◽  
Last Ice Age ◽  
Sea Currents ◽  
Wind Sea

AbstractIn the light of data from the Greenland ice sheet concerning the ice-age climate, and palaeoecological studies of interglacial and Early Holocene deposits, the concept that a large proportion of Greenland's plants and animals may have survived during the ice ages is evaluated. While ice-free areas (refugias) were present, it is concluded that only hardy, cold-adapted species could have survived, which also explains why so few clearly endemic species are present in Greenland. Most members of the present biota are considered to be postglacial immigrants. Some species came to Greenland by walking or flying, but most arrived by passive, long-distance, chance dispersal, carried by wind, sea currents, and, in particular, birds. Transport by birds may explain why so many species arrived from Europe, because vast numbers of geese in particular migrate from northwest Europe to Greenland.

scholarly journals Long-term time series of Arctic tropospheric BrO derived from UV–VIS satellite remote sensing and its relation to first-year sea ice

2020 ◽  
Vol 20 (20) ◽  
pp. 11869-11892
Author(s):  
Ilias Bougoudis ◽  
Anne-Marlene Blechschmidt ◽  
Andreas Richter ◽  
Sora Seo ◽  
John Philip Burrows ◽  
...  
Keyword(s):  
Time Series ◽  
Sea Ice ◽  
Ice Age ◽  
The Arctic ◽  
First Year ◽  
Vertical Column ◽  
Chain Reactions ◽  
Heterogeneous Chain ◽  
Good Agreement

Abstract. Every polar spring, phenomena called bromine explosions occur over sea ice. These bromine explosions comprise photochemical heterogeneous chain reactions that release bromine molecules, Br2, to the troposphere and lead to tropospheric plumes of bromine monoxide, BrO. This autocatalytic mechanism depletes ozone, O3, in the boundary layer and troposphere and thereby changes the oxidizing capacity of the atmosphere. The phenomenon also leads to accelerated deposition of metals (e.g., Hg). In this study, we present a 22-year (1996 to 2017) consolidated and consistent tropospheric BrO dataset north of 70∘ N, derived from four different ultraviolet–visible (UV–VIS) satellite instruments (GOME, SCIAMACHY, GOME-2A and GOME-2B). The retrieval data products from the different sensors are compared during periods of overlap and show good agreement (correlations of 0.82–0.98 between the sensors). From our merged time series of tropospheric BrO vertical column densities (VCDs), we infer changes in the bromine explosions and thus an increase in the extent and magnitude of tropospheric BrO plumes during the period of Arctic warming. We determined an increasing trend of about 1.5 % of the tropospheric BrO VCDs per year during polar springs, while the size of the areas where enhanced tropospheric BrO VCDs can be found has increased about 896 km2 yr−1. We infer from comparisons and correlations with sea ice age data that the reported changes in the extent and magnitude of tropospheric BrO VCDs are moderately related to the increase in first-year ice extent in the Arctic north of 70∘ N, both temporally and spatially, with a correlation coefficient of 0.32. However, the BrO plumes and thus bromine explosions show significant variability, which also depends, apart from sea ice, on meteorological conditions.

scholarly journals Plankton, from the last ice age to the year 3007

2008 ◽  
Vol 65 (3) ◽  
pp. 296-301 ◽  
Author(s):  
E. C. Pielou
Keyword(s):  
Positive Feedback ◽  
Climate Changes ◽  
Thermohaline Circulation ◽  
Canadian Arctic ◽  
Ice Age ◽  
Climate Forcing ◽  
The Arctic ◽  
Mackenzie Delta ◽  
The Past ◽  
Last Ice Age

Abstract Pielou, E. C. 2008. Plankton, from the last ice age to the year 3007. – ICES Journal of Marine Science, 65: 296–301. Climate forcing of the environment and biota has been happening since time immemorial, human forcing only for the past 200 years or so. This paper considers, first, climatic changes over the past 30 000 years, as indicated by plankton and their effects on plankton. Only fossilizable plankton can be observed: principally foraminifera, radiolaria, and pteropods in the zooplankton, and their food, principally coccolithophores, diatoms, and dinoflagellate cysts, in the phytoplankton. The soft-bodied zooplankton species—especially copepods—that lived with them can only be inferred. Large, abrupt climate changes took place, aided by positive feedback. Second, this paper attempts to predict how human forcing in the form of anthropogenic climate change is likely to affect marine ecosystems in the future. Past predictions have underestimated the speed at which warming is actually happening: positive feedback has been unexpectedly strong. Thus, the melting of snow and ice, by reducing the earth's albedo, has increased the amount of solar energy absorbed. Also, warming of the surface (water and land) has caused outgassing of methane from buried clathrates (hydrates), and methane is a strong greenhouse gas. Currently, predictions emphasize one or the other of two contrasted alternatives: abrupt cooling caused by a shutdown of the thermohaline circulation (the “ocean conveyor”) or abrupt warming caused by copious outgassing of methane. Both arguments (the former from oceanographers and the latter from geophysicists) are equally persuasive, and I have chosen to explore the methane alternative, because I am familiar with an area (the Beaufort Sea and Mackenzie Delta) where outgassing has recently (2007) been detected and is happening now: in the Arctic Ocean and the Canadian Arctic Archipelago, where disappearance of the ice will affect currents, temperature, thermocline, salinity, upwelling, and nutrients, with consequent effects on the zooplankton.

scholarly journals Remote Sensing-Based Statistical Approach for Defining Drained Lake Basins in a Continuous Permafrost Region, North Slope of Alaska

2021 ◽  
Vol 13 (13) ◽  
pp. 2539
Author(s):  
Helena Bergstedt ◽  
Benjamin M. Jones ◽  
Kenneth Hinkel ◽  
Louise Farquharson ◽  
Benjamin V. Gaglioti ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Statistical Approach ◽  
Wildlife Habitat ◽  
The Arctic ◽  
North Slope ◽  
Landsat 8 ◽  
The North ◽  
North Slope Of Alaska ◽  
Permafrost Regions ◽  
Lake Basins

Lake formation and drainage are pervasive phenomena in permafrost regions. Drained lake basins (DLBs) are often the most common landforms in lowland permafrost regions in the Arctic (50% to 75% of the landscape). However, detailed assessments of DLB distribution and abundance are limited. In this study, we present a novel and scalable remote sensing-based approach to identifying DLBs in lowland permafrost regions, using the North Slope of Alaska as a case study. We validated this first North Slope-wide DLB data product against several previously published sub-regional scale datasets and manually classified points. The study area covered >71,000 km2, including a >39,000 km2 area not previously covered in existing DLB datasets. Our approach used Landsat-8 multispectral imagery and ArcticDEM data to derive a pixel-by-pixel statistical assessment of likelihood of DLB occurrence in sub-regions with different permafrost and periglacial landscape conditions, as well as to quantify aerial coverage of DLBs on the North Slope of Alaska. The results were consistent with previously published regional DLB datasets (up to 87% agreement) and showed high agreement with manually classified random points (64.4–95.5% for DLB and 83.2–95.4% for non-DLB areas). Validation of the remote sensing-based statistical approach on the North Slope of Alaska indicated that it may be possible to extend this methodology to conduct a comprehensive assessment of DLBs in pan-Arctic lowland permafrost regions. Better resolution of the spatial distribution of DLBs in lowland permafrost regions is important for quantitative studies on landscape diversity, wildlife habitat, permafrost, hydrology, geotechnical conditions, and high-latitude carbon cycling.

scholarly journals Long-term Time-series of Arctic Tropospheric BrO derived from UV-VIS Satellite Remote Sensing and its Relation to First Year Sea Ice

2020 ◽  
Author(s):  
Ilias Bougoudis ◽  
Anne-Marlene Blechschmidt ◽  
Andreas Richter ◽  
Sora Seo ◽  
John Philip Burrows ◽  
...  
Keyword(s):  
Time Series ◽  
Sea Ice ◽  
Ice Age ◽  
The Arctic ◽  
First Year ◽  
Arctic Amplification ◽  
Vertical Column ◽  
The Impact ◽  
Good Agreement

Abstract. Arctic Amplification describes the rapid increase of the air temperature in the past three decades in the Arctic, which impacts on physicochemical conditions, the ecosystem and biogeochemistry. Every polar spring, the BrO explosion, a series of chemical reactions that release bromine molecules to the troposphere occurs over sea ice covered regions. This autocatalytic mechanism depletes boundary layer and tropospheric ozone, thereby changes the oxidizing capacity of the atmosphere and facilitates the deposition of metals (e.g. Hg). In this study, we present a 22 year consolidated and consistent tropospheric BrO dataset, derived from four different UV-VIS satellite instruments and investigate the BrO evolution under the impact of Arctic Amplification. The retrieval data products from the different sensors are compared during periods of overlap and show good agreement. By studying the sensor merged time-series of tropospheric BrO vertical column densities, we find an increase in the magnitude of BrO explosion events under the impact of Arctic Amplification with an upward trend of about 1.5 % per year. Furthermore, the areas where BrO plumes frequently appear have changed, extending over larger regions in the Arctic during more recent years. Comparison to sea ice age data suggests that the reported changes in tropospheric BrO are linked in a complex way to the increase of first-year ice extent in the Arctic.

Investigating the Relation of Arctic Tropospheric Bro Derived by Satellite Remote Sensing to Sea Ice Age and Meteorological Driving Mechanisms Under the Impact of Arctic Amplification

2020 ◽  
Author(s):  
Ilias Bougoudis ◽  
Anne-Marlene Blechschmidt ◽  
Andreas Richter ◽  
Sora Seo ◽  
John Burrows
Keyword(s):  
Wind Speed ◽  
Sea Ice ◽  
Air Temperature ◽  
Ice Age ◽  
Atmospheric Composition ◽  
The Arctic ◽  
Arctic Amplification ◽  
German Research Foundation ◽  
The Impact

<p>Arctic Amplification, the rapid increase of air temperature in higher latitudes over the last decades, is expected to have drastic impacts on all the sub-systems of the Arctic ecosystem. Bromine Oxides play a key role in the atmospheric composition of the Arctic. During polar spring, bromine molecules are released from young sea ice covered regions.  A rapid chemical chain reaction starts, the -so called 'bromine explosion', which depletes ozone, alters the production of OH, and thereby eventually changes the oxidizing capacity of the troposphere. Halogens oxidize elemental to gaseous mercury, which may then be deposited and harm the ecosystem. Based on current literature, there is considerable uncertainty on the impact of Arctic Amplification on halogen evolution. On one hand, the melting of multi-year sea ice should result in formation of more young sea ice, which favors bromine release. On the other hand, BrO explosion events are triggered by low temperatures, an effect expected to be reduced due to Arctic Amplification. Moreover, changes of other meteorological drivers, such as cyclone frequency and wind speed may impact on BrO amounts in the Arctic troposphere.</p><p>In this study, a long-term time-series of tropospheric BrO derived from 4 UV-VIS instruments (GOME, SCIAMACHY, GOME-2A, GOME-2B) is used as a basis, in order to investigate the impact of Arctic Amplification on BrO amounts in the Arctic. The long-term BrO data is being compared to sea ice age (NSIDC) and meteorological (air temperature, mean sea level pressure, wind speed and boundary layer height from ERA-5 & ASR-2) data. Our results focus on determining the relation between tropospheric BrO and its drivers, and especially on how the drivers impact on the formation of BrO plumes. Different cases studies throughout the 22 years of the BrO dataset were performed and evaluated. The changes in the tropospheric BrO abundances come in general agreement with changes in the drivers of BrO explosion events.</p><p> </p><p>We gratefully acknowledge the funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Projektnummer 268020496 – TRR 172, within the Transregional Collaborative Research Center “ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms (AC)³”.</p>

scholarly journals Diverging Trends Between Heterozygosity and Allelic Richness During Postglacial Colonization in the European Beech

Genetics ◽  
2001 ◽  
Vol 157 (1) ◽  
pp. 389-397 ◽  
Author(s):  
B Comps ◽  
D Gömöry ◽  
J Letouzey ◽  
B Thiébaut ◽  
R J Petit
Keyword(s):  
Allelic Richness ◽  
Gene Diversity ◽  
European Beech ◽  
Ice Age ◽  
Simultaneous Increase ◽  
Long Distance ◽  
Southeastern Part ◽  
The Balkans ◽  
Isozyme Loci ◽  
Last Ice Age

Abstract Variation at 12 polymorphic isozyme loci was studied in the European beech on the basis of an extensive sample of 389 populations distributed throughout the species range. Special emphasis was given to the analysis of the pattern of geographic variation on the basis of two contrasting measures of genetic diversity, gene diversity (H) and allelic richness, and to their relationship. Measures of allelic richness were corrected for variation in sample size by using the rarefaction method. As expected, maximum allelic richness was found in the southeastern part of the range (southern Italy and the Balkans), where beech was confined during the last ice age. Surprisingly, H was lower in refugia than in recently colonized regions, resulting in a negative correlation between the two diversity measures. The decrease of allelic richness and the simultaneous increase of H during postglacial recolonization was attributed to several processes that differentially affect the two diversity parameters, such as bottlenecks due to long-distance founding events, selection during population establishment, and increased gene flow at low population densities.

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