Stoll Heather

Stoll Heather
ETH Zurich | ETH Zürich · Department of Earth Sciences

PhD Princeton University 1998

About

230
Publications
39,072
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5,159
Citations
Citations since 2017
74 Research Items
2404 Citations
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20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
Additional affiliations
January 2009 - August 2010
University of Massachusetts Amherst
May 2005 - present
Universidad de Oviedo
January 2002 - August 2008
Williams College

Publications

Publications (230)
Preprint
Speleothem fluorescence may elucidate past vegetation dynamics, while microscale fluorescent laminations can provide annually resolved chronology. However, the origin of speleothem fluorescence and the mechanism responsible for the formation of micrometer scale fluorescent lamination in stalagmites, are not well constrained by monitoring studies. H...
Article
Recent advances in geochemical techniques mean that several robust proxies now exist to determine the past carbonate chemistry of the oceans. Foraminiferal δ11B and alkenone carbon isotopes allow us to reconstruct sea-surface pH and pCO2, respectively, and the ability to apply both proxies to the same sediment sample would give strongly paired data...
Preprint
Full-text available
Understanding the variations in past ocean carbonate chemistry is critical in elucidating the role of the oceans in balancing the global carbon cycle. The fossil shells from marine calcifiers present in the sedimentary record are widely applied as past ocean carbon cycle proxies. However, the interpretation of these records can be challenging due t...
Preprint
Full-text available
Cave monitoring studies clarify the climatic, surface vegetation, and karst processes affecting the cave system and lay the foundation to interpreting geochemical stalagmite records. Here we report monitoring of cave air, bedrock chemistry, and drip water δ13CDIC, δ18O and δD as well as 16 trace elements covering a full annual cycle spanning 16 mon...
Article
Full-text available
Coccolithophores are calcifying marine phytoplankton whose intracellularly produced calcite plates, coccoliths, have been the dominant source of calcium carbonate in open-ocean settings since the Cretaceous. An open question is whether their calcification has been affected by changing environmental conditions over geological timescales such as vari...
Preprint
Full-text available
The carbon isotopic signature inherited from soil/epikarst processes may be modified by degassing and prior calcite precipitation (PCP) before its imprint on speleothem calcite. Despite laboratory demonstration of PCP effects on carbon isotopes and increasingly sophisticated models of the governing processes, to date, there has been limited effort...
Preprint
Full-text available
Recent advances in geochemical techniques mean that several robust proxies now exist to determine the past carbonate chemistry of the oceans. Foraminiferal δ11B and alkenone carbon isotopes allow us to reconstruct sea-surface pH and pCO2 respectively, and the ability to apply both proxies to the same sediment sample would give strongly paired datas...
Article
Full-text available
The rate and consequences of future high latitude ice sheet retreat remain a major concern given ongoing anthropogenic warming. Here, new precisely dated stalagmite data from NW Iberia provide the first direct, high-resolution records of periods of rapid melting of Northern Hemisphere ice sheets during the penultimate deglaciation. These records re...
Preprint
Full-text available
Coccolithophores are calcifying marine phytoplankton whose intracellularly produced calcite plates, or coccoliths, have been the dominant source of calcium carbonate in open ocean settings since the Cretaceous. An open question is whether their calcification has been affected by variation in environmental parameters such as the ocean carbon system...
Conference Paper
Full-text available
For decades, the Oligocene has been a relatively overlooked period. Nevertheless, this time span (34.5-23 Ma) is gathering increasing attention because recent estimates of CO2 levels and the size of the Antartic ice-sheets are comparable to their present-day values, highlighting the potential of Oligocene climate variability to better model the sen...
Preprint
Ocean acidification increases pCO2 and decreases pH of seawater and its impact on marine organisms has emerged as a key research focus. In addition to directly measured variables such as growth or calcification rate, stable isotopic tracers such as carbon isotopes have also been used to more completely understand the physiological processes contrib...
Conference Paper
Full-text available
Coccoliths formed by coccolithophores, the dominant group of marine calcifying phytoplankton, play a key role in the marine carbon cycle. Culture experiments have shown a strong sensitivity in size and their calcification to changing CO2 and ocean acidification. Therefore, there is significant interest in quantifying these physiological parameters...
Article
This study presents the first high-resolution speleothem-based hydrological reconstruction for much of the last 2.7 kyr in the central-western Mediterranean. The paleohydrological information comes from a combination of five U-Th dated stalagmites from two Mallorca island caves. Interpretations are based on high-resolution records of δ¹⁸O, δ¹³C and...
Article
Because they can archive a variety of geochemical proxies and be precisely and accurately dated with the U-Th decay series chronometer, stalagmites are widely used for paleoclimate reconstructions. However, limitations in the use of this chronometer arise because U-Th dating is analytically time consuming, expensive, and requires a relatively large...
Article
Full-text available
The temperate region of western Europe underwent significant climatic and environmental change during the last deglaciation. Much of what is known about the terrestrial ecosystem response to deglacial warming stems from pollen preserved in sediment sequences, providing information on vegetation composition. Other ecosystem processes, such as soil r...
Article
Full-text available
Large Antarctic ice volume changes characterized the middle to Late Oligocene and the first million years of climate evolution during the Miocene. However, the sea surface temperature (SST) evolution over this period remains poorly constrained, as only a few records from contrasting proxies are available. In this study, we present a long-term alken...
Article
Full-text available
The sensitivity of coccolithophores to changing CO2 and its role in modulating cellular photosynthetic carbon isotopic fractionation (εp) is crucial to understand i) the future adaptation of these organisms to higher CO2 world and ii) to assess the reliability of εp for past CO2 estimation. Here, we present εp measured on natural fossil samples acr...
Article
Full-text available
For the first time, this article presents a large dataset of precipitation isotopic measurements (δ18Op and δ2Hp) sampled every day or 2 d from seven sites on a west-to-east transect across northern Spain for 2010–2017. The main aim of this study is to (1) characterize the rainfall isotopic variability in northern Spain at daily and monthly timesca...
Article
Full-text available
Here, we map a series of stalagmites from Asturias, Spain, by laser ablation inductively-coupled-plasma mass spectrometry and confocal laser scanning (fluorescence) microscopy and discuss the origins of trace element and fluorescence variations. Seasonal banding is evident with both methods and may be attributed to lignins/humic acids based on fluo...
Article
Full-text available
Throughout Earth's history, CO 2 is thought to have exerted a fundamental control on environmental change. Here we review and revise CO 2 reconstructions from boron isotopes in carbonates and carbon isotopes in organic matter over the major climate transition of the past 66 million years. We find close coupling between CO 2 and climate throughout t...
Article
Full-text available
The Miocene epoch (23.03-5.33 Ma) was a time interval of global warmth, relative to today. Continental configurations and mountain topography transitioned toward modern conditions, and many flora and fauna evolved into the same taxa that exist today. Miocene climate was dynamic: long periods of early and late glaciation bracketed a ∼2 Myr greenhous...
Article
Full-text available
The Miocene epoch (23.03–5.33 Ma) was a time interval of global warmth, relative to today. Continental configurations and mountain topography transitioned toward modern conditions, and many flora and fauna evolved into the same taxa that exist today. Miocene climate was dynamic: long periods of early and late glaciation bracketed a ∼2 Myr greenhous...
Article
Full-text available
Coccolithophores are one of the major contributors to the pelagic production of calcium carbonate and their fossilized remains are a key component of the biogeochemical cycles of calcium (Ca), magnesium (Mg), and other divalent cations present in the intracellular precipitated calcitic structures (coccoliths). The geochemical signature of coccolith...
Article
Full-text available
Coccolithophores play a key role in the marine carbon cycle and ecosystem. The carbonate shells produced by coccolithophore, named as coccolith, could be well preserved in the marine sediment for millions of years and become an excellent archive for paleoclimate studies. The micro-filtering and sinking–decanting methods have been successfully desig...
Preprint
Full-text available
Periodic ~400 kyr orbital scale variations in the ocean carbon cycle, manifest in indicators of deep sea dissolution and benthic 13C, have been observed throughout the Cenozoic but the driving mechanisms remain under debate. Changes in coccolithophore productivity may change the global rain ratio (Corganic: Cinorganic fluxes from ocean into sedimen...
Preprint
Full-text available
The temperate region of Western Europe underwent dramatic climatic and environmental change during the last deglaciation. Much of what is known about the terrestrial ecosystem response to deglacial warming stems from pollen preserved in sediment sequences, providing information on vegetation composition. Other ecosystem processes, such as soil resp...
Preprint
Full-text available
Coccolithophore play a key role in the marine carbon cycle and ecosystem. The 9 carbonate shells produced by coccolithophore, named as coccolith, could be well preserved in the marine sediment for million years and become an excellent archive for paleoclimate studies. The micro filtering and sinking-decanting method have been successfully designed...
Article
Full-text available
Culture experiments with coccolithophore algae ‐ the dominant group of marine calcifying phytoplankton – imply a strong sensitivity in growth rate, degree of cellular calcification and cell size to changes in the carbon chemistry of their growth environment. These results underpin recent studies that have explored how these physiological parameters...
Article
Full-text available
A pronounced late Miocene cooling (LMC) from ~7 to 5.7Ma has been documented in extratropical and tropical sea surface temperature records, but to date, available proxy evidence has not revealed a significant pCO2 decline over this event. Here, we provide a new, high resolution pCO2 proxy record over the late Miocene cooling based on alkenone carbo...
Article
Full-text available
Coccolithophores contribute significantly to marine primary productivity and play a unique role in ocean biogeochemistry by using carbon for photosynthesis (soft-tissue pump) and for calcification (carbonate counter pump). Despite the importance of including coccolithophores in Earth system models to allow better predictions of the climate system's...
Article
Estimates of past pCO2 prior to ice‐core records have often been sought by measuring carbon isotopic fractionation during photosynthesis (Ɛp) in alkenone‐producing algae present in the fossil record. Photic zone and core‐top Ɛp show strong latitudinal gradients, which have been interpreted as an effect of growth rate. The factor b, used in previous...
Article
Full-text available
Coccolithophores are a group of phytoplankton widely distributed in the ocean, which secrete extracellular calcite plates termed coccoliths. Coccoliths have been increasingly employed as an archive for geochemical, ecological and paleoclimate studies in recent years. A robust application of coccolith-based geochemical proxies relies on understandin...
Preprint
Full-text available
This article presents for the first time a large dataset of rainfall isotopic measurements (d18Op and d2Hp) sampled every day or every two days from seven sites in a west-to-east transect across northern Spain for 2010–2017. The main aim of this study is to: (1) characterize rainfall isotopic variability in northern Spain at daily and monthly time...
Article
Full-text available
Membrane permeabilities to CO2 and HCO3‐ constrain the function of CO2 concentrating mechanisms that algae use to supply inorganic carbon for photosynthesis. In diatoms and green algae, plasma‐membranes are moderately to highly permeable to CO2 but effectively impermeable to HCO3‐. Here, CO2 and HCO3‐ membrane permeabilities were measured using an...
Conference Paper
Full-text available
Coccolithophores play an important dual role in ocean biogeochemistry: they use dissolved inorganic carbon (DIC) in the surface for both photosynthesis and coccolith calcification. Stable isotopes in coccoliths are the result of various effects, including different vital effects, allowing hypotheses about the varying active carbon acquisition strat...
Article
In 1990, an oceanographer who had never worked on climate science proposed that ice-age cooling has been amplified by increased concentrations of iron in the sea — and instigated an explosion of research. A historic breakthrough that explains a global climate feedback.
Article
Rubisco‐catalyzed CO2 fixation is the main source of organic carbon in the biosphere. This enzyme is present in all domains of life with different forms (III, II, and I) and its origin goes back to 3,500 million years, when the atmosphere was anoxygenic. However, the Rubisco active site also catalyzes oxygenation of ribulose 1,5‐bisphosphate, there...
Article
This study explores the climatic variability in the Iberian Peninsula (IP) and its surrounding seas from 140 to 65 kyr BP. Marine sediment cores and cave speleothems are used to reconstruct changes in sea surface water conditions, deep sea current intensities and atmospheric moisture availability based on stable isotopes, trace elements, grain size...
Preprint
Full-text available
Abstract. Coccolithophores contribute significantly to the marine primary productivity and play a unique role in ocean biogeochemistry by using carbon for photosynthesis (biological pump) and also for calcification (carbonate pump). Despite the importance of including coccolithophores in global climate models to allow better predictions of the clim...
Poster
A large geochemestry were analyzed in a stalagmite from Ardales Cave (SW-Spain) to assess paleoclimate. The stalagmite was actively growing in 2007 upon collection and U-Th dates suggest that began forming 1000 years ago. Large variations in Mg/Ca ratios occur on both seasonal and multidecadal timescales. We infer that in dry periods there would be...
Article
Full-text available
Antarctic ice sheet margin extent and the sensitivity of benthic δ18O to orbital forcing have varied on million‐year timescales during the Oligocene to Early Miocene. However, few Sea Surface Temperature (SST) records for this time interval exist to evaluate links between polar processes and mean temperature outside polar regions. Here, we present...
Poster
We report a paleoclimatological study of Northwest Spain using "Paz", a stalagmite collected in the Cave of Pindal (Asturias) located about 10m from the Cantabrian Sea. We describe trace element and isotopic results from a growth phase between 9000BP and 450 BP according U/Th dates. The average growth rate in "Paz" is 27 microns/year, but between 3...
Conference Paper
Full-text available
Coccolithophores, marine calcifying organisms, are primary producers of calcite in the ocean. It is generated as coccosphere, an exoskeleton formed by coccoliths, which span micrometer scale in size and thickness. It was hypostasized that atmospheric changes in carbon dioxide have a direct impact in the ocean carbon budget, and therefore, coccolith...
Article
Full-text available
We compiled modern and fossil relative abundance of coccolithophore species Florisphaera profunda from published and unpublished datasets, along with ocean environmental variable data from satellite remote sensing and physical measurements. The database includes relative abundances of F. profunda in sediment trap (n = 26) and core-top (n = 1258), a...
Article
Ocean net primary productivity (Npp) is a key component of the marine carbon cycle. Multi-model Npp projections based on a few decades of satellite data show large uncertainties, in particular at low latitudes (30 NÀ30 S). Calibration of sedimentary proxies with satellite-based Npp estimates allows for the quantitative reconstruction of this variab...
Article
Full-text available
This study was conducted in Ejulve cave (Spain, southwestern Europe) over a period of four years (2013–2016) to identify the factors affecting the isotopic composition of rainfall, dripwaters, and farmed calcite. The results indicate that δ¹⁸O of rainfall in the study area was mainly controlled by the temperature effect (r² = 0.82, p-value < 0.001)...
Article
Full-text available
Quantification sinking velocities of individual coccoliths will contribute to optimizing laboratory methods for separating coccoliths of different sizes and species for geochemical analysis. The repeated settling–decanting method was the earliest method proposed to separate coccoliths from sediments and is still widely used. However, in the absence...
Article
Coccolithophores play a key role in the oceanic carbon cycle through the biological and carbonate pumps. Understanding controls on coccolithophore productivity is thus fundamental to quantify oceanic carbon cycling. We investigate changes in coccolithophore productivity over several Pleistocene glacial-interglacial cycles using a high-resolution co...
Conference Paper
Full-text available
Major changes in the carbon cycle and atmospheric CO 2 along the Cenozoic have been suggested to be a determining cause of the climatic evolution from a ''green-house Earth' to an 'ice Earth', driving the global temperature and limiting the polar ice sheet growth. During the Oligocene-Miocene time interval, pCO 2 atmospheric concentrations are esti...
Presentation
Full-text available
Detailed analysis of the lamination and the geochemical varibility of the speleothem Zerolin to study the paleoclimate of SE Spain.
Article
Full-text available
The sinking velocities of individual coccoliths are relevant for export of their CaCO3 from the surface ocean, and for laboratory methods to separate coccoliths of different sizes and species for geochemical analysis. In the laboratory, the repeat settling/decanting method was the earliest method to separate coccolith from sediments for geochemical...
Article
Full-text available
As major calcifiers in the open ocean, coccolithophores play a key role in the marine carbon cycle. Because they may be sensitive to changing CO2 and ocean acidification, there is significant interest in quantifying past and present variations in their cellular calcification by quantifying the thickness of the coccoliths or calcite plates that cove...
Article
Coccoliths comprise a major fraction of the global carbonate sink. Therefore, changes in coccolithophores’ Ca isotopic fractionation could affect seawater Ca isotopic composition, affecting interpretations of the global Ca cycle and related changes in seawater chemistry and climate. Despite this, a quantitative interpretation of coccolith Ca isotop...
Article
Extratropical sea surface temperature records from alkenones record a dramatic cooling of up to 17 °C over the last ∼14 Ma, but the relationship between this cooling and greenhouse gas forcing has been elusive due to sparse and contrasting reconstructions of atmospheric CO2 for the time period. Alkenone carbon isotopic fractionation during photosyn...
Article
Full-text available
Significance We present an outstanding speleothem record that reconstructs the vegetation activity and hydrological availability during Termination III (T-III) in Southern Europe throughout δ ¹³ C, δ ¹⁸ O, and Mg/Ca variations. The results reveal for the North Atlantic region the sequence of abrupt stadial events during T-III, in close analogy to t...
Conference Paper
Full-text available
The carbon dioxide (CO2) decline during the Cenozoic is hypothesized to have played an important role in the climate system, driving global temperature variations and conditioning polar ice sheets. Coccolithophores, unicellular calcifying phytoplankton, are especially sensitive to changing CO2 concentrations. Therefore, the carbon isotopic composit...