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Klimaforschung

Der Klimawandel ist eine der größten Bedrohungen der menschlichen Zivilisation. Klimaszenarien der Zukunft können nur auf Basis dessen berechnet werden, was wir über die Vergangenheit wissen. Durch das Verständnis der Variabilität des Klimas und der Mechanismen, welche die globalen Klimakreisläufe beeinflussen, sind Wissenschaftler in der Lage, anspruchsvolle Modelle unseres zukünftigen Klimas zu entwickeln und liefern entscheidende Informationen für die Öffentlichkeit und Regierungen über mögliche Konsequenzen anthropogener Aktivitäten.

Die Stabilisotopenanalyse fungiert als ein virtuelles Paläothermometer, an dem vergangene Temperaturen von einer Vielzahl von Materialien wie Mikrofossilien, Eisbohrkernen und Baumringen abgelesen werden können. Durch das Kombinieren dieser Temperaturinformationen und der Extrapolation der Daten in die Zukunft sind wir in der Lage, die schlimmsten Auswirkungen des Klimawandels zu verhindern. Die Stabilisotopenanalyse wird eine entscheidene Rolle spielen, uns dabei zu helfen.

Carbonate

Klimasignale liegen am Meeresgrund in Form von sedimentierten Carbonaten altertümlicher Biota vor. Die 13C and 18O Isotopenverhältnisse dieser Materialien stehen in direktem Zusammenhang mit der Meerestemperatur und dem Zeitraum ihrer Existenz. Unser Dual Inlet System, ausgestattet mit MultiCarb, ist in der Lage, 13C and 18O Analysen von extrem kleinen Proben mit der höchsten Präzision durchzuführen, und ermöglicht die aufregend neue "clumped isotope" Analysenmethode.

» MultiCarb

Wasseranalyse aus Eisbohrkernen

Das Isotopenverhältnis des Niederschlags ist abhängig von der Temperatur der Ozeane, aus denen das Wasser verdunstet. Eisbohrkerne aus den arktischen und antarktischen Polarregionen haben die Variation der Isotope über Jahrtausende aufgezeichnet und ermöglichen es, die Temperatur zu dem Zeitpunkt zu rekonstruieren, als das Eis entstand. Verglichen mit anderen Techniken ist unser AquaPrep ist in der Lage, höchste 18O und 2H Analysen durchzuführen, was Unsicherheiten in Ihren Temperaturproxyberechnungen reduziert.

» AquaPrep

Treibhausgase

Treibhausgase in der Atmosphäre sind die Haupttreiber des Klimawandels. Um die Mechanismen des Klimawandels zu verstehen, ist die Entkopplung des anthropogenen Beitrags dieser Gase in die Atmosphäre von solchen, die das Ergebnis natürlicher Prozesse sind, entscheidend. Mit iso FLOW können die Isotopenverhältnisse der wichtigsten Treibhausgase CO2, N2O und CH4 in atmosphärischen Gasproben untersucht werden. Die Ergebnisse dieser Analysen können dabei helfen, Strategien zum Umgang mit dem Klimawandel zu entwickeln.

Publikationen zum Thema Klimawandel mit unseren Geräten

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115 Ergebnisse:

Morphological and Dietary Responses of Chipmunks to a Century of Climate Change.
Global change biology (2016)
Rachel E Walsh, Ana Paula A Assis, James L Patton, Gabriel Marroig, Todd E Dawson, Eileen A Lacey

Predicting how individual taxa will respond to climatic change is challenging, in part because the impacts of environmental conditions can vary markedly, even among closely related species. Studies of chipmunks (Tamias spp.) in Yosemite National Park provide an important opportunity to explore the reasons for this variation in response. While the alpine chipmunk (T. alpinus) has undergone a significant elevational range contraction over the past century, the congeneric and partially sympatric lodgepole chipmunk (T. speciosus) has not experienced an elevational range shift during this period. As a first step toward identifying the factors underlying this difference in response, we examined evidence for dietary changes and changes in cranial morphology in these species over the past century. Stable isotope analyses of fur samples from modern and historical museum specimens of these species collected at the same localities indicated that signatures of dietary change were more pronounced in T. alpinus, although diet breadth did not differ consistently between the study species. Morphometric analyses of crania from these specimens revealed significant changes in cranial shape for T. alpinus, with less pronounced changes in shape for T. speciosus; evidence of selection on skull morphology was detected for T. alpinus but not T. speciosus. These results are consistent with growing evidence that T. alpinus is generally more responsive to environmental change than T. speciosus but emphasize the complex and often geographically variable nature of such responses. Accordingly, future studies that make use of the taxonomically and spatially integrative approach employed here may prove particularly informative regarding relationships between environmental conditions, range changes, and patterns of phenotypic variation. This article is protected by copyright. All rights reserved.
Schlagworte: carbon , nitrogen , ecol , clim , elem

Measurements of 14C in ancient ice from Taylor Glacier, Antarctica constrain in situ cosmogenic 14CH4 and 14CO production rates
Geochimica et Cosmochimica Acta (2016)
Vasilii V. Petrenko, Jeffrey P. Severinghaus, Hinrich Schaefer, Andrew M. Smith, Tanner Kuhl, Daniel Baggenstos, Quan Hua, Edward J. Brook, Paul Rose, Robb Kulin, Thomas Bauska, Christina Harth, Christo Buizert, Anais Orsi, Guy Emanuele, James E. Lee, Gor

Carbon-14 (14C) is incorporated into glacial ice by trapping of atmospheric gases as well as direct near-surface in situ cosmogenic production. 14C of trapped methane (14CH4) is a powerful tracer for past CH4 emissions from “old” carbon sources such as permafrost and marine CH4 clathrates. 14C in trapped carbon dioxide (14CO2) can be used for absolute dating of ice cores. In situ produced cosmogenic 14C in carbon monoxide (14CO) can potentially be used to reconstruct the past cosmic ray flux and past solar activity. Unfortunately, the trapped atmospheric and in situ cosmogenic components of 14C in glacial ice are difficult to disentangle and a thorough understanding of the in situ cosmogenic component is needed in order to extract useful information from ice core 14C. We analyzed very large (≈1000kg) ice samples in the 2.26–19.53m depth range from the ablation zone of Taylor Glacier, Antarctica, to study in situ cosmogenic production of 14CH4 and 14CO. All sampled ice is >50ka in age, allowing for the assumption that most of the measured 14C originates from recent in situ cosmogenic production as ancient ice is brought to the surface via ablation. Our results place the first constraints on cosmogenic 14CH4 production rates and improve on prior estimates of 14CO production rates in ice. We find a constant 14CH4/14CO production ratio (0.0076±0.0003) for samples deeper than 3m, which allows the use of 14CO for correcting the 14CH4 signals for the in situ cosmogenic component. Our results also provide the first unambiguous confirmation of 14C production by fast muons in a natural setting (ice or rock) and suggest that the 14C production rates in ice commonly used in the literature may be too high.

Pliocene-Pleistocene evolution of sea surface and intermediate water temperatures from the Southwest Pacific
Paleoceanography (2016)
Erin L. McClymont, Aurora C. Elmore, Sev Kender, Melanie J. Leng, Mervyn Greaves, Henry Elderfield

Over the last 5 million years, the global climate system has evolved toward a colder mean state, marked by large amplitude oscillations in continental ice volume. Equatorward expansion of polar waters and strengthening temperature gradients have been detected. However, the response of the mid- and high-latitudes of the southern hemisphere is not well documented, despite the potential importance for climate feedbacks including sea ice distribution and low-high latitude heat transport. Here, we reconstruct the PliocenePleistocene history of both sea surface and Antarctic Intermediate Water (AAIW) temperatures on orbital timescales from DSDP Site 593 in the Tasman Sea, Southwest Pacific. We confirm overall Pliocene-Pleistocene cooling trends in both the surface ocean and AAIW, although the patterns are complex. The Pliocene is warmer than modern, but our data suggest an equatorward displacement of the subtropical front relative to present, and a poleward displacement of the subantarctic front of the Antarctic Circumpolar Current (ACC). Two main intervals of cooling, from c.3 Ma and c.1.5 Ma, are coeval with cooling and icesheet expansion noted elsewhere, and suggest that equatorward expansion of polar water masses also characterised the Southwest Pacific through the Pliocene-Pleistocene. However, the observed trends in SST and AAIW temperature are not identical despite an underlying link to the ACC, and intervals of unusual surface ocean warmth (c.2 Ma) and large amplitude variability in AAIW temperatures (from c.1 Ma) highlight complex interactions between equatorward displacements of fronts associated with the ACC and/or varying poleward heat transport from the subtropics.
Schlagworte: carbon , oxygen , ocea , clim , mulitcarb

Chemodenitrification in the cryoecosystem of Lake Vida, Victoria Valley, Antarctica
Geobiology (2016)
N. E. Ostrom, H. Gandhi, G. Trubl, A. E. Murray

Lake Vida, in the Victoria Valley of East Antarctica, is frozen, yet harbors liquid brine (~20% salt, >6 times seawater) intercalated in the ice below 16 m. The brine has been isolated from the surface for several thousand years. The brine conditions (permanently dark, −13.4 °C, lack of O2, and pH of 6.2) and geochemistry are highly unusual. For example, nitrous oxide (N2O) is present at a concentration among the highest reported for an aquatic environment. Only a minor 17O anomaly was observed in N2O, indicating that this gas was predominantly formed in the lake. In contrast, the 17O anomaly in nitrate (inline image) in Lake Vida brine indicates that approximately half or more of the inline image present is derived from atmospheric deposition. Lake Vida brine was incubated in the presence of 15N-enriched substrates for 40 days. We did not detect microbial nitrification, dissimilatory reduction of inline image to ammonium (inline image), anaerobic ammonium oxidation, or denitrification of N2O under the conditions tested. In the presence of 15N-enriched nitrite (inline image), both N2 and N2O exhibited substantial 15N enrichments; however, isotopic enrichment declined with time, which is unexpected. Additions of 15N–inline image alone and in the presence of HgCl2 and ZnCl2 to aged brine at −13 °C resulted in linear increases in the δ15N of N2O with time. As HgCl2 and ZnCl2 are effective biocides, we interpret N2O production in the aged brine to be the result of chemodenitrification. With this understanding, we interpret our results from the field incubations as the result of chemodenitrification stimulated by the addition of 15N-enriched inline image and ZnCl2 and determined rates of N2O and N2 production of 4.11–41.18 and 0.55–1.75 nmol L−1 day−1, respectively. If these rates are representative of natural production, the current concentration of N2O in Lake Vida could have been reached between 6 and 465 years. Thus, chemodenitrification alone is sufficient to explain the high levels of N2O present in Lake Vida.
Schlagworte: nitrogen , oxygen , clim , gashead

Ecosystem nitrogen fixation throughout the snow-free period in subarctic tundra: effects of willow and birch litter addition and warming
Global Change Biology (2016)
Kathrin Rousk, Anders Michelsen

Nitrogen (N) fixation in moss-associated cyanobacteria is one of the main sources of available N for N-limited ecosystems such as subarctic tundra. Yet, N2 fixation in mosses is strongly influenced by soil moisture and temperature. Thus, temporal scaling up of low-frequency in situ measurements to several weeks, months or even the entire growing season without taking into account changes in abiotic conditions cannot capture the variation in moss-associated N2 fixation. We therefore aimed to estimate moss-associated N2 fixation throughout the snow-free period in subarctic tundra in field experiments simulating climate change: willow (Salix myrsinifolia) and birch (Betula pubescens spp. tortuosa) litter addition, and warming. To achieve this, we established relationships between measured in situ N2 fixation rates and soil moisture and soil temperature and used high-resolution measurements of soil moisture and soil temperature (hourly from May to October) to model N2 fixation. The modelled N2 fixation rates were highest in the warmed (2.8 ± 0.3 kg N ha−1) and birch litter addition plots (2.8 ± 0.2 kg N ha−1), and lowest in the plots receiving willow litter (1.6 ± 0.2 kg N ha−1). The control plots had intermediate rates (2.2 ± 0.2 kg N ha−1). Further, N2 fixation was highest during the summer in the warmed plots, but was lowest in the litter addition plots during the same period. The temperature and moisture dependence of N2 fixation was different between the climate change treatments, indicating a shift in the N2 fixer community. Our findings, using a combined empirical and modelling approach, suggest that a longer snow-free period and increased temperatures in a future climate will likely lead to higher N2 fixation rates in mosses. Yet, the consequences of increased litter fall on moss-associated N2 fixation due to shrub expansion in the Arctic will depend on the shrub species’ litter traits.
Schlagworte: nitrogen , soil , clim , elem

Using oxygen isotopes to quantitatively assess residual CO2 saturation during the CO2CRC Otway Stage 2B Extension residual saturation test
International Journal of Greenhouse Gas Control (2016)
Sascha Serno, Gareth Johnson, Tara C. LaForce, Jonathan Ennis-King, Ralf R. Haese, Christopher J. Boreham, Lincoln Paterson, Barry M. Freifeld, Paul J. Cook, Dirk Kirste, R. Stuart Haszeldine, Stuart M.V. Gilfillan

Residual CO2 trapping is a key mechanism of secure CO2 storage, an essential component of the Carbon Capture and Storage technology. Estimating the amount of CO2 that will be residually trapped in a saline aquifer formation remains a significant challenge. Here, we present the first oxygen isotope ratio (δ18O) measurements from a single-well experiment, the CO2CRC Otway 2B Extension, used to estimate levels of residual trapping of CO2. Following the initiation of the drive to residual saturation in the reservoir, reservoir water δ18O decreased, as predicted from the baseline isotope ratios of water and CO2, over a time span of only a few days. The isotope shift in the near-wellbore reservoir water is the result of isotope equilibrium exchange between residual CO2 and water. For the region further away from the well, the isotopic shift in the reservoir water can also be explained by isotopic exchange with mobile CO2 from ahead of the region driven to residual, or continuous isotopic exchange between water and residual CO2 during its back-production, complicating the interpretation of the change in reservoir water δ18O in terms of residual saturation. A small isotopic distinction of the baseline water and CO2 δ18O, together with issues encountered during the field experiment procedure, further prevents the estimation of residual CO2 saturation levels from oxygen isotope changes without significant uncertainty. The similarity of oxygen isotope-based near-wellbore saturation levels and independent estimates based on pulsed neutron logging indicates the potential of using oxygen isotope as an effective inherent tracer for determining residual saturation on a field scale within a few days.

Individual Migration Pathways of Modern Planktic Foraminifers: Chamber-by-Chamber Assessment of Stable Isotopes
Paleontological Research (2016)
Haruka Takagi, Kazuyoshi Moriya, Toyoho Ishimura, Atsushi Suzuki, Hodaka Kawahata, Hiromichi Hirano

Abstract. The stable carbon (δ13C) and oxygen isotopes (δ18O) of planktic foraminiferal tests have been widely used as proxies in paleoceanography and paleoclimatology. The ontogenetic isotopic profiles of foraminifers are also thought to record ecological information about species, such as changes in habitat depth and symbiotic relationships. However, isotopic profiles during “individual ontogeny” have rarely been examined. In this study, we report the ontogenetic isotopic information for three net-collected modern species, Globigerinoides sacculifer, Neogloboquadrina dutertrei, and Globorotalia inflata, together with several in situ oceanographic parameters of the water column in Sagami Bay, Japan (seawater temperature, salinity, nutrients, chlorophyll a content, δ13C of dissolved inorganic carbon [DIC], and δ18O of seawater). We examined the ontogenetic profiles of the foraminifers with chamber dissection and chamber-by-chamber analyses of δ13C and δ18O using a specially designed continuous-flow mass s...
Schlagworte: carbon , oxygen , geol , clim , mulitcarb

Ecosystem nitrogen fixation throughout the snow-free period in subarctic tundra: effects of willow and birch litter addition and warming
Global Change Biology (2016)
Kathrin Rousk, Anders Michelsen

Nitrogen (N) fixation in moss-associated cyanobacteria is one of the main sources of available N for N-limited ecosystems such as subarctic tundra. Yet, N2 fixation in mosses is strongly influenced by soil moisture and temperature. Thus, temporal scaling up of low-frequency in situ measurements to several weeks, months or even the entire growing season without taking into account changes in abiotic conditions cannot capture the variation in moss-associated N2 fixation. We therefore aimed to estimate moss-associated N2 fixation throughout the snow-free period in subarctic tundra in field experiments simulating climate change: willow (Salix myrsinifolia) and birch (Betula pubescens spp. tortuosa) litter addition, and warming. To achieve this, we established relationships between measured in situ N2 fixation rates and soil moisture and soil temperature and used high-resolution measurements of soil moisture and soil temperature (hourly from May to October) to model N2 fixation. The modelled N2 fixation rates were highest in the warmed (2.8 ± 0.3 kg N ha−1) and birch litter addition plots (2.8 ± 0.2 kg N ha−1), and lowest in the plots receiving willow litter (1.6 ± 0.2 kg N ha−1). The control plots had intermediate rates (2.2 ± 0.2 kg N ha−1). Further, N2 fixation was highest during the summer in the warmed plots, but was lowest in the litter addition plots during the same period. The temperature and moisture dependence of N2 fixation was different between the climate change treatments, indicating a shift in the N2 fixer community. Our findings, using a combined empirical and modelling approach, suggest that a longer snow-free period and increased temperatures in a future climate will likely lead to higher N2 fixation rates in mosses. Yet, the consequences of increased litter fall on moss-associated N2 fixation due to shrub expansion in the Arctic will depend on the shrub species’ litter traits.
Schlagworte: nitrogen , soil , clim , elem

Using oxygen isotopes to quantitatively assess residual CO2 saturation during the CO2CRC Otway Stage 2B Extension residual saturation test
International Journal of Greenhouse Gas Control (2016)
Sascha Serno, Gareth Johnson, Tara C. LaForce, Jonathan Ennis-King, Ralf R. Haese, Christopher J. Boreham, Lincoln Paterson, Barry M. Freifeld, Paul J. Cook, Dirk Kirste, R. Stuart Haszeldine, Stuart M.V. Gilfillan

Residual CO2 trapping is a key mechanism of secure CO2 storage, an essential component of the Carbon Capture and Storage technology. Estimating the amount of CO2 that will be residually trapped in a saline aquifer formation remains a significant challenge. Here, we present the first oxygen isotope ratio (δ18O) measurements from a single-well experiment, the CO2CRC Otway 2B Extension, used to estimate levels of residual trapping of CO2. Following the initiation of the drive to residual saturation in the reservoir, reservoir water δ18O decreased, as predicted from the baseline isotope ratios of water and CO2, over a time span of only a few days. The isotope shift in the near-wellbore reservoir water is the result of isotope equilibrium exchange between residual CO2 and water. For the region further away from the well, the isotopic shift in the reservoir water can also be explained by isotopic exchange with mobile CO2 from ahead of the region driven to residual, or continuous isotopic exchange between water and residual CO2 during its back-production, complicating the interpretation of the change in reservoir water δ18O in terms of residual saturation. A small isotopic distinction of the baseline water and CO2 δ18O, together with issues encountered during the field experiment procedure, further prevents the estimation of residual CO2 saturation levels from oxygen isotope changes without significant uncertainty. The similarity of oxygen isotope-based near-wellbore saturation levels and independent estimates based on pulsed neutron logging indicates the potential of using oxygen isotope as an effective inherent tracer for determining residual saturation on a field scale within a few days.
Schlagworte: hydrogen , oxygen , clim , aquap

Individual Migration Pathways of Modern Planktic Foraminifers: Chamber-by-Chamber Assessment of Stable Isotopes
Paleontological Research (2016)
Haruka Takagi, Kazuyoshi Moriya, Toyoho Ishimura, Atsushi Suzuki, Hodaka Kawahata, Hiromichi Hirano

Abstract. The stable carbon (δ13C) and oxygen isotopes (δ18O) of planktic foraminiferal tests have been widely used as proxies in paleoceanography and paleoclimatology. The ontogenetic isotopic profiles of foraminifers are also thought to record ecological information about species, such as changes in habitat depth and symbiotic relationships. However, isotopic profiles during “individual ontogeny” have rarely been examined. In this study, we report the ontogenetic isotopic information for three net-collected modern species, Globigerinoides sacculifer, Neogloboquadrina dutertrei, and Globorotalia inflata, together with several in situ oceanographic parameters of the water column in Sagami Bay, Japan (seawater temperature, salinity, nutrients, chlorophyll a content, δ13C of dissolved inorganic carbon [DIC], and δ18O of seawater). We examined the ontogenetic profiles of the foraminifers with chamber dissection and chamber-by-chamber analyses of δ13C and δ18O using a specially designed continuous-flow mass s...
Schlagworte: carbon , oxygen , geol , clim , mulitcarb