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  • 1
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    Klima-Änderungen im Pleistozän: Isotopenuntersuchungen an fossilen Seesedimenten aus dem Holstein-Interglazial Ost-Polens (2011)
    Geozon Science Media
    Details
    Publication Date: 2021-03-29
    Description: In Ost-Polen erbohrte Seesedimente mit einer Mächtigkeit bis zu 55 m (Ossówka-See) dokumentieren das ganze Holstein-Interglazial und die Anfangsperiode der Saale-Eiszeit. An ausgewählten Bohrkernen der Seen von Ossówka und Wilczyn wurden palaeobiologische (Malakofauna, Palynologie und Pflanzen-Makroreste) und Isotopen-Untersuchungen durchgeführt. Die für den längsten (55 m) und vollständigsten Bohrkern nahe der Ortschaft Ossówka bestimmten C- und O-Isotopenwerte betragen: δ13C: Minimalwerte bis -6,4 ‰ für Ablagerungen am Beginn des Interglazials, Maximalwerte bis +10,0‰ für Ablagerungen aus der kalten Frühglazialperiode; δ18O: Maximalwerte bis -3,6 ‰ für Ablagerungen aus dem ersten Abschnitt des Interglazial-Optimums, Minimalwerte bis -10,1 ‰ für Ablagerungen aus der kältesten Periode unmittelbar vor der nächsten Vereisung. Generell gibt der Kurvenverlauf der O-Isotopenwerte gut die palynologisch dokumentierten Klimaveränderungen wieder. Im Profil sind jedoch zwei Perioden zu beobachten, in denen das Isotopenbild nicht mit der palynologischen Aussage übereinstimmt, einmal im klimatischen Interglazial-Optimum und zum anderen im jüngeren Teil des frühen Saale-Glazials. 1. Während des klimatischen Optimums des Holstein-interglazials (Pollen-Zone G und H) sprechen die Isotopenkurven der Seesedimente für relativ kühle Klimaverhältnisse. Dies kann durch eine Zunahme der Niederschlagsmenge, die zu einer Seespiegel-Erhöhung führte und/oder durch den Einfluß von isotopisch leichten Zuflüssen erklärt werden. 2. Im oberen Teil des Profils, der eine kühle, der Vereisung vorangehende Phase darstellt, erreichen die δ13C-und δ18O-Isotope unerwartet hohe Werte, was möglicherweise auf die Redeposition von "warmen" interglazialen Ablagerungen und/oder auf eine Zunahme der Evaporation unter trockenen Steppenklima-Bedingungen mit Seespiegel-Tiefständen zurückzuführen ist. Abkühlungsphasen fallen mit der Verschiebung der Sauerstoffisotopenverhältnisse in Richtung einer 18O- Verarmung zusammen.
    Description: research
    Keywords: 551.7 ; VAR 000 ; Glazialgeologie ; climate change ; lacustrine sediments ; holsteinian interglacial ; C/O isotopes
    Language: German
    Type: article , publishedVersion
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  • 2
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    Does Export Production Measure Transient Changes of the Biological Carbon Pump's Feedback to the Atmosphere Under Global Warming? (2021)
    Details
    Publication Date: 2021-07-05
    Description: In a widely‐held conception, the biological carbon pump (BCP) is equal to the export of organic matter out of the euphotic zone. Using global ocean‐atmosphere model experiments we show that the change in export production is a poor measure of the biological pump's feedback to the atmosphere. The change in global true oxygen utilization (TOU), an integrative measure of the imprint of the BCP on marine oxygen, however, is in good agreement with the net change in the biogenic air‐sea flux of oxygen. Since TOU correlates very well with apparent oxygen utilization (AOU) in our experiments, we propose to measure the change of AOU from data of global float programs to monitor the feedback of the BCP to the atmosphere. For the current ocean we estimate that BCP changes effect a CO2 uptake by the ocean in the range of 0.07 to 0.14 GtC/yr.
    Description: Plain Language Summary: The biological carbon pump is an important element of marine carbon cycling and climate control on millennium timescales. In a widely‐held conception the export of organic carbon from the productive surface layer of the ocean is used as the essential measure of this carbon pump. Using numerical ocean modeling, we show here that the change in export production is, however, a poor measure of the biological carbon pump's feedback to the atmosphere on centennial timescales. In the contrary, we find that an oxygen‐based measure, the apparent oxygen utilization can be used to quantify the impact of biological pump changes on the atmosphere. Since the apparent oxygen utilization is easily accessible from an existing network of marine floats, our study suggests that the atmospheric impact of any future changes of the biological carbon pump can be monitored and quantified. For past decades our study proposes a negligible CO2 feedback to climate from biological carbon processing.
    Description: Key Points: Apparent oxygen utilization is proposed to quantify the feedback of the biological carbon pump to the atmosphere in a warming ocean. Changes in export production are unrelated to changes in biotic oxygen air‐sea gas exchange. The CO2‐flux due to changes of the biological carbon pump over the recent decades is negligible compared to the total marine CO2 uptake.
    Description: Deutsche Forschungsgemeinschat
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: 551.9 ; biological carbon pump ; export production ; climate change ; AOU
    Type: article
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  • 3
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    Vegetation Trajectories and Shortwave Radiative Forcing Following Boreal Forest Disturbance in Eastern Siberia (2021)
    Details
    Publication Date: 2021-06-28
    Description: Major boreal forest disturbance and associated carbon emissions have been reported in the coldest region of the Northern Hemisphere. Related biophysical feedbacks to climate remain highly uncertain but might reduce warming effects expected from carbon emissions. This study quantifies albedo change after disturbance, primarily fires, in larch‐dominated forests around Yakutsk as compared to undisturbed areas with natural albedo variability, using satellite‐based time series. The related annual mean shortwave radiative forcing was −6.015 W/m2 for the 13 years following forest disturbance. It was highly negative during snow‐covered months (−3.738 to −13.638 W/m2), but positive (+5.441 W/m2) for the summer months in the first year after disturbance, decreasing afterward and also turning into a negative forcing after 5 years. Forcing by surface shortwave radiation must be considered to assess the impact of boreal forest disturbance on climate and additional feedbacks, such as increased permafrost thaw or transition to alternative ecosystem states.
    Description: Plain Language Summary: Boreal forests of northeastern Siberia are experiencing disturbances such as fires and permafrost degradation. These disturbances can trigger changes in biomass and heating dynamics resulting in major feedbacks to the local and regional climate. This study quantifies albedo, the ratio of reflected sunlight to incoming sunlight, in a larch‐dominated forest area in Siberia over a time span of 13 years after fire disturbance. Land surface albedo showed significant changes due to larch forest disturbance, which often recovered to a birch‐dominated forest. During summer months of the first 4 years after the forest fire, the decrease in albedo caused a local warming. For snow‐covered seasons, forest disturbance and the corresponding albedo change caused low local cooling directly after disturbance, and this cooling effect increased during the following decade.
    Description: Key Points: Major boreal forest cover disturbance in the coldest region of the Northern Hemisphere (Yakutsk, Siberia) during 2001–2014 resulted in a significant change in surface albedo Surface albedo change‐related mean annual surface shortwave radiative forcing was −6.015 W/m2 but varied with season and strongly decreased during the 13 years following disturbance Shortwave radiative forcing can be directly linked to a vegetation trajectory from deciduous needleleaf to broadleaf dominated forest
    Keywords: 333.7 ; albedo ; climate change ; wildfire ; vegetation trajectory ; larch ; radiative forcing
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  • 4
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    Late Pleistocene to Holocene vegetation and climate changes in northwestern Chukotka (Far East Russia) deduced from lakes Ilirney and Rauchuagytgyn pollen records (2021)
    Details
    Publication Date: 2021-07-21
    Description: This paper presents two new pollen records and quantitative climate reconstructions from northern Chukotka documenting environmental changes over the last 27.9 ka. Open tundra‐ and steppe‐like habitats dominated between 27.9 and 18.7 cal. ka BP. Betula and Alnus shrubs might have grown in sheltered microhabitats but disappeared after 18.7 cal. ka BP. Although the climate was rather harsh, local herb‐dominated communities supported herbivores as is evident by the presence of coprophilous spores in the sediments. The increase in Salix and Cyperaceae ~16.1 cal. ka BP suggests climate amelioration. Shrub Betula appeared ~15.9 cal. ka BP, and became dominant after ~15.52 cal. ka BP, whilst typical steppe communities drastically reduced. Very high presence of Botryococcus in the Lateglacial sediments reflects widespread shallow habitats, probably due to lake level increase. Shrub Alnus became common after ~13 cal. ka BP reflecting further climate amelioration. Simultaneously, herb communities gradually decreased in the vegetation reaching a minimum ~11.8 cal. ka BP. A gradual decrease of algae remains suggests a reduction of shallow‐water habitats. Shrubby and graminoid tundra was dominant ~11.8–11.1 cal. ka BP, later Salix stands significantly decreased. The forest‐tundra ecotone established in the Early Holocene, shortly after 11.1 cal. ka BP. Low contents of green algae in the Early Holocene sediments likely reflect deeper aquatic conditions. The most favourable climate conditions were between ~10.6 and 7 cal. ka BP. Vegetation became similar to the modern after ~7 cal. ka BP but Pinus pumila came to the Ilirney area at about 1.2 cal. ka BP. It is important to emphasize that the study area provided refugia for Betula and Alnus during MIS 2. It is also notable that our records do not reflect evidence of Younger Dryas cooling, which is inconsistent with some regional environmental records but in good accordance with some others.
    Description: European Research Council
    Keywords: 561 ; arctic Chukotka ; Late Pleistocene ; Holocene ; lacustrine sediments ; pollen stratigraphy ; climate change
    Type: article
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  • 5
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    Kartographie als Klimaarchiv - Meereis im Norden, vom Eis verschlossene Schiffspassagen und verstoßende Gletscher - alte Karten dokumentieren die »Kleine Eiszeit« (2011)
    Geozon Science Media
    Details
    Publication Date: 2021-03-29
    Description: Im 15. Jh. weisen Tabulae modernae und Weltkarten lateinischer Ptolemäus-Ausgaben auf Meereis in Nordeuropa hin. Zu Beginn des 17. Jh. scheitert die Suche nach einer Nordwestpassage nach Asien. Das Mittelalterliche Klimaoptimum ist zu Ende gegangen und erst um 1850 - am Ende der „Kleinen Eiszeit“ - ist diese Passage befahrbar. Den Klimawandel in der Frühen Neuzeit belegen auch Jahreszeitenbilder seit dem Mittelalter und Augenscheinkarten ab 1500. Letztere dokumentieren mehrfach die Einstellung von Weinbau und das zum Teil katastrophale Vorrücken der Alpengletscher. Die Gletscherhochstände des 17. Jh. und jener am Ende des 18. Jh. sind umfangreich in Karten und Veduten festgehalten. Ab 1565 malt Pieter Brueghel Winterbilder und im gesamten 17. Jh. gestalten flämische und holländische Künstler Landschaften mit Schnee und Eis. Zu Beginn des 19. Jh. malt Caspar David Friedrich bemerkenswerte Bilder mit Eis. In der Mitte des 19. Jh. entstehen erste Gletscherkarten, sie halten dabei unbeabsichtigt den letzten Hochstand der Alpengletscher fest. Ab 1880 beginnen genaue Kartierungen, welche den Rückzug der Alpengletscher dokumentieren.
    Description: research
    Keywords: 551.7 ; VAR 000 ; Glazialgeologie ; little ice age ; climate change ; climate history ; history of cartography ; art history ; latin ptolemy-editions ; manuscript maps ; regional maps ; proxidates ; sea ice ; glacier ; viticulture
    Language: German
    Type: article , publishedVersion
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  • 6
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    Grassland greening on the Mongolian Plateau despite higher grazing intensity (2021)
    John Wiley & Sons, Ltd. | Chichester, UK
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    Publication Date: 2021-06-28
    Description: Changes in land management and climate alter vegetation dynamics, but the determinants of vegetation changes often remain elusive, especially in global drylands. Here we assess the determinants of grassland greenness on the Mongolian Plateau, one of the world's largest grassland biomes, which covers Mongolia and the province of Inner Mongolia in China. We use spatial panel regressions to quantify the impact of precipitation, temperature, radiation, and the intensity of livestock grazing on the normalized difference vegetation indices (NDVI) during the growing seasons from 1982 to 2015 at the county level. The results suggest that the Mongolian Plateau experienced vegetation greening from 1982 to 2015. Precipitation and animal density were the most influential factors contributing to higher NDVI on the grasslands of Inner Mongolia and Mongolia. Our results highlight the dominant effect of climate variability, and especially of the precipitation variability, on the grassland greenness in Mongolian drylands. The findings challenge the common belief that higher grazing pressure is the key driver for land degradation. The analysis exemplifies how representative wall‐to‐wall results for large areas can be attained from exploring space–time data and adds empirical insights to the puzzling relationship between grazing intensity and vegetation growth in dryland areas.
    Description: European Union's Framework Programme for Research and Innovation ‐ Horizon 2020 (2014‐2020)
    Description: Alexander von Humboldt Foundation of Germany
    Keywords: 333.7 ; China ; climate change ; grassland ; livestock grazing ; NDVI ; spatial panel regression ; vegetation growth
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  • 7
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    Muslims and climate change: How Islam, Muslim organizations, and religious leaders influence climate change perceptions and mitigation activities (2021)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2021-06-27
    Description: A growing body of research stresses the importance of religion in understanding and addressing climate change. However, so far, little is known about the relationship between Muslim communities and climate change. Globally, Muslims constitute the second largest faith group, and there is a strong concentration of Muslims in regions that are particularly affected by global warming. This review synthesizes existing research about climate change and Muslim communities. It addresses (a) Islamic environmentalism, (b) Muslim perceptions of climate change, and (c) mitigation strategies of Muslim communities. The analysis shows that there is no uniform interpretation of climate change among Muslims. Based on their interpretations of Islam, Muslims have generated different approaches to climate change. A small section of Muslim environmentalists engages in public campaigning to raise greater concern about climate change, seeks to reduce carbon emissions through sociotechnological transition efforts, and disseminates proenvironmental interpretations of Islam. However, it remains unclear to what extent these activities generate broader changes in the daily activities of Muslim communities and organizations. Contributions to this research field are often theoretical and stress theological and normative aspects of Islam. Empirical studies have particularly addressed Indonesia and the United Kingdom, whereas knowledge about Muslim climate activism in other world regions is fragmented. Against this backdrop, there is a need for comparative studies that consider regional and religious differences among Muslims and address the role of Muslim environmentalism in climate change mitigation and adaptation at the international, national, and local scales. This article is categorized under: Social Status of Climate Change Knowledge 〉 Sociology/Anthropology of Climate Knowledge
    Keywords: 304 ; climate change ; Islam ; Islamic environmentalism ; Muslims ; religion ; sustainability
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  • 8
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    Response of large benthic foraminifera to climate and local changes: Implications for future carbonate production (2021)
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    Publication Date: 2021-07-21
    Description: Large benthic foraminifera are major carbonate components in tropical carbonate platforms, important carbonate producers, stratigraphic tools and powerful bioindicators (proxies) of environmental change. The application of large benthic foraminifera in tropical coral reef environments has gained considerable momentum in recent years. These modern ecological assessments are often carried out by micropalaeontologists or ecologists with expertise in the identification of foraminifera. However, large benthic foraminifera have been under‐represented in favour of macro reef‐builders, for example, corals and calcareous algae. Large benthic foraminifera contribute about 5% to modern reef‐scale carbonate sediment production. Their substantial size and abundance are reflected by their symbiotic association with the living algae inside their tests. When the foraminiferal holobiont (the combination between the large benthic foraminifera host and the microalgal photosymbiont) dies, the remaining calcareous test renourishes sediment supply, which maintains and stabilizes shorelines and low‐lying islands. Geological records reveal episodes (i.e. late Palaeocene and early Eocene epochs) of prolific carbonate production in warmer oceans than today, and in the absence of corals. This begs for deeper consideration of how large benthic foraminifera will respond under future climatic scenarios of higher atmospheric carbon dioxide (pCO2) and to warmer oceans. In addition, studies highlighting the complex evolutionary associations between large benthic foraminifera hosts and their algal photosymbionts, as well as to associated habitats, suggest the potential for increased tolerance to a wide range of conditions. However, the full range of environments where large benthic foraminifera currently dwell is not well‐understood in terms of present and future carbonate production, and impact of stressors. The evidence for acclimatization, at least by a few species of well‐studied large benthic foraminifera, under intensifying climate change and within degrading reef ecosystems, is a prelude to future host–symbiont resilience under different climatic regimes and habitats than today. This review also highlights knowledge gaps in current understanding of large benthic foraminifera as prolific calcium carbonate producers across shallow carbonate shelf and slope environments under changing ocean conditions.
    Description: Minerva Foundation http://dx.doi.org/10.13039/501100001658
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: 561 ; Bioindicators ; carbonate engineers ; climate change ; environmental stressors ; ocean acidification ; photosymbionts ; sea‐level rise ; water quality
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  • 9
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    Quantifying Nitrous Oxide Emissions in the U.S. Midwest: A Top‐Down Study Using High Resolution Airborne In‐Situ Observations (2021)
    Details
    Publication Date: 2021-07-21
    Description: The densely farmed U.S. Midwest is a prominent source of nitrous oxide (N2O) but top‐down and bottom‐up N2O emission estimates differ significantly. We quantify Midwest N2O emissions by combining observations from the Atmospheric Carbon and Transport‐America campaign with model simulations to scale the Emissions Database for Global Atmospheric Research (EDGAR). In October 2017, we scaled agricultural EDGAR v4.3.2 and v5.0 emissions by factors of 6.3 and 3.5, respectively, resulting in 0.42 nmol m−2 s−1 Midwest N2O emissions. In June/July 2019, a period when extreme flooding was occurring in the Midwest, agricultural scaling factors were 11.4 (v4.3.2) and 9.9 (v5.0), resulting in 1.06 nmol m−2 s−1 Midwest emissions. Uncertainties are on the order of 50 %. Agricultural emissions estimated with the process‐based model DayCent (Daily version of the CENTURY ecosystem model) were larger than in EDGAR but still substantially smaller than our estimates. The complexity of N2O emissions demands further studies to fully characterize Midwest emissions.
    Description: Plain Language Summary: Nitrous oxide (N2O) is the third most important anthropogenic greenhouse gas contributing to the warming of the planet and the dominant man‐made ozone‐depleting substance in the stratosphere. Its atmospheric concentrations have been rising since industrialization mainly due to an increase in anthropogenic sources, with agriculture being the dominant source. The densely farmed U.S. Midwest plays an important role in the global N2O budget. However, previous studies that have collected observations of N2O indicate that estimates of surface emissions in the Midwest are substantially underestimating the truth. In this study, we combine unique aircraft‐based N2O measurements and model simulations to quantify Midwest emissions in October 2017 and June/July 2019. Agricultural inventory estimates had to be increased by factors up to 20 to match observations, revealing a large underestimation in current inventories. An extreme flooding event in 2019 when the summer observations occurred may be responsible for some of this discrepancy. Estimations of soil N2O emissions calculated with a state‐of‐the‐art biogeochemical model show less underestimation but are still too low compared to the fluxes derived from the aircraft observational data.
    Description: Key Points: Within the ACT‐America project, we gathered a unique airborne in‐situ N2O data set over the U.S. Midwest with enhancements up to 9  ppb. N2O emissions in the U.S. Midwest were on average 0.42 ± 0.28 nmol m−2 s−1 in October 2017 and 1.06 ± 0.57 nmol m−2 s−1 in June to July 2019. Bottom‐up estimates from EDGAR and DayCent underestimate U.S. Midwest N2O emissions by factors up to 20.
    Keywords: agriculture ; climate change ; flux estimate ; Midwest ; nitrous oxide ; top‐down
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  • 10
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    Luminescence Chronology of the Schwalbenberg II Loess in the Middle Rhine Valley (2011)
    Geozon Science Media
    Details
    Publication Date: 2021-05-07
    Description: Der Vergleich von „multiple aliquot“ Protokoll basierten IRSL- und TL-Altern mit denen von „single aliquot regenerative“ Protokollen mittels des post-IR IRSL (225°C) und fading-korrigierten IR (50°C) zeigt, dass Signalverlust durch anomales Ausheilen für Lösse und Lössderivate des Schwalbenberg II Profils ein geringes Problem darstellt. Aus diesem Grund ist es sehr wahrscheinlich, dass auf „multiple aliquot“ Messprotokollen beruhende Lumineszenz-Datierungen, die in den 1990er Jahren im allgemeinen für Lösse aus dem Mittelrheingebiet angewendet wurden, bis zu einem Alter von 70–80 ka innerhalb der 1-sigma Fehlerabweichung verlässliche IRSL und TL-Alter ergeben haben. Die Löss-/Paläobodensedimente des Schwalbenberg II Lössprofils zeigen einen bemerkenswert detaillierte weichselzeitliche mittelpleniglaziale Abfolge, die mit dem marinen Sauerstoffisotopenstadium 3 korreliert wird. Ein verlässlicher chronologischer Rahmen wurde durch Lumineszenz-Datierungsmethoden bestimmt. Vier Löss-Hauptakkumulationsphasen konnten für die letztglaziale Abfolge vom Schwalbenberg nachgewiesen werden. Die chronologischen Ergebnisse unterstützen die litho-pedologische Korrelation der Hesbaye Formation mit MIS 2 und der Ahrgau Formation mit MIS 3. Aufgrund von litho-pedologischen Befunden wird die Keldach Formation mit MIS 4 korreliert. Die Lumineszenz-Alter von 55 bis 45 ka legen jedoch eine Korrelation mit MIS 3 nahe.
    Description: research
    Keywords: 551.7 ; VAR 000 ; Glazialgeologie ; pleistocene ; germany ; loess ; pléistocène ; climate change ; luminescence dating
    Language: English
    Type: article , publishedVersion
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