Maarten Blaauw

Queen's University Belfast, Geography, Archaeology and Palaeoecology, Faculty Member

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My background is in palaeo-ecology (PhD, University of Amsterdam, The Netherlands, 2003), and I am interested in using statistics to answer palaeo-ecological questions.

I am working on:

* Bayesian software for C-14 age-modelling
* Statistical/ecological interpretation of proxy archives

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Papers by Maarten Blaauw

Half-precessional dynamics of monsoon rainfall near the East African Equator

Nature, 2009

Late Holocene linkages between decade–century scale climate variability and productivity at Lake Tanganyika, Africa

by Pierre Denis Plisnier and Maarten Blaauw

Journal of Paleolimnology, 2006

Microlaminated sediment cores from the Kalya slope region of Lake Tanganyika provide a near-annua... more Microlaminated sediment cores from the Kalya slope region of Lake Tanganyika provide a near-annually resolved paleoclimate record between~2,840 and 1,420 cal. yr B.P. demonstrating strong linkages between climate variability and lacustrine productivity. Laminae couplets comprise dark, terrigenous-dominated half couplets, interpreted as low density underflows deposited from riverine sources during the rainy season, alternating with light, planktonic diatomaceous ooze, with little terrigenous component, interpreted as windy/dry season deposits. Laminated portions of the studied cores consist of conspicuous dark and light colored bundles of laminae couplets. Light and dark bundles alternate at decadal time scales. Within dark bundles, both light and dark half couplets are significantly thinner than within light bundles, implying slower sediment accumulation rates during both seasons over those intervals.

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A 10,500 year record of summer temperatures in Central Europe from cave glaciers

A wealth of data has accumulated over the past decade on the links between the North Atlantic (NA... more A wealth of data has accumulated over the past decade on the links between the North Atlantic (NA) climate and ocean variability and its influence on the European climate. However, most of the studies have been restricted to the area in the immediate vicinity of the NA, with little or no data existing west of the Alps. This region lies at both the eastern limit of the direct influence of the NA climate, and the western one of the continental Asian climate, thus being of extreme importance in understanding the workings of climate and its forcings. In this paper, we present a 10,500 years long record of climatic changes in Central Europe, based on stable isotope analyses of cave ice. The first order fluctuations broadly follow the orbitally induced Northern Hemisphere September insolation, with a minimum in the early Holocene, a slow climb towards a maximum at ~5.0 ka, followed by a very slow cooling towards the present, accentuated after ~0.5 ka. Superimposed on the long-term variati...

Sun-climate relationships: the evidence form Lateglacial and Holocene terrestrial deposits

Soc Sci Med, 2002

KNAW Narcis. Back to search results. Publication Sun-climate relationships: the evidence form Lat... more

Testing teleconnections - chronological uncertainties of independently dated and tuned past climate events (Invited)

Multiple fossil proxy archives are often dated by aligning purportedly simultaneous events betwee... more Multiple fossil proxy archives are often dated by aligning purportedly simultaneous events between data sets. Examples are synchronising peat layers across countries or continents, orbital tuning, and dating cores through aligning proxy features with δ18O series from marine and ice deposits. Any temporal mismatch between multiple sites are then attributed to chronological errors, e.g., changing 14C age offsets, unidentified hiatuses or other mistakes in age-models. However, tuning involves the real danger of erroneously "sucking" separate events into one illusionary event, or vice versa. As an alternative, past climate events can be dated independently (e.g. using 14C dating), while explicitly quantifying their chronological uncertainties. Instead of assuming simultaneous climate events between multiple archives, the age models are kept separate, and the timing of events tested by calculating the probability of simultaneous events within a defined period of time. The method is tested by comparing Dansgaard/Oeschger-like events in two well-dated sites; Les Echets in France and NGRIP in Greenland. Chronological uncertainties are so high that we cannot safely assume that climate events were synchronous between sites at decadal to multi-centennial time scales. Past climate research would profit if tuning procedures would become more quantitative, reliable and objective. Ideally, individual proxy archives should not be tuned, and kept on independent time-scales.

Evidence from North-West European bogs showing that Little Ice Age climatic changes were driven by changes in solar activity

J Natur Hist, 2001

Lake Challa (Mt. Kilimanjaro) sediments as recorder of present and past seasonality in equatorial East Africa

In discussions on the impact of global warming on moisture balance and human water resources, nat... more In discussions on the impact of global warming on moisture balance and human water resources, natural archives of past hydrological variability in tropical regions are attracting increasing attention. The EuroCLIMATE project CHALLACEA studies the sediment archive of Lake Challa, a 4.5 km² and ~94 m deep crater lake located on the lower eastern slope of Mt. Kilimanjaro with the aim

Carbon-water dynamics in European High Arctic mires of Svalbard over the last few thousand years

The Arctic region of Europe is expected to undergo further dramatic environmental change in the c... more The Arctic region of Europe is expected to undergo further dramatic environmental change in the coming century that could destabilize large amounts of belowground carbon, which is concentrated in Arctic peatlands. To address the sensitivity of Arctic peatland carbon over the recent past we investigated several mire sites in the inner fjords of western Svalbard, Norway. Organic deposits were studied to assess the sensitivity of mire carbon-water linkages to past climate variation. Carbon-rich Svalbard mires store about 26 to 61 kg C m-2 in deposits as thick as 1.4 m. Our own AMS radiocarbon measurements together with a survey of the published literature show that sequestered carbon in Svalbard mires is typically of mid- to late-Holocene age. We use radiocarbon measurements of fossil bryophytes together with Bayesian calibration and Monte Carlo simulations to quantify uncertainties in carbon sequestration. A pattern of highly variable carbon accumulation was identified that ranged fro...

Reproducibility of neutron activated Sm-153 in tablets intended for human volunteer studies

IFMBE Proceedings, 2009

Neutron activation of Sm-152 offers a method of radiolabeling for the in vivo study of oral dose ... more Neutron activation of Sm-152 offers a method of radiolabeling for the in vivo study of oral dose formulations by gamma scintigraphy. Reproducibility measurements are needed to ensure the robustness of clinical studies. 204 enteric-coated guaifenesin core tablets (10 mg of Sm 2 O 3 ) were irradiated by thermal neutrons to achieve 1 MBq at 48 h. Administered activities were 0.86 7 0.03 MBq. Good reproducibility (CV¼ 3.5%) was observed over 24 weeks ensuring that volunteer doses were within the dose reference level of 0.8 mSv.

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Air pollutant contamination and acidification of surface waters in the North York Moors, UK: Multi-proxy evidence from the sediments of a moorland pool

The Holocene, 2014

ABSTRACT Despite the extensive geographical range of palaeolimnological studies designed to asses... more ABSTRACT Despite the extensive geographical range of palaeolimnological studies designed to assess the extent of surface water acidification in the United Kingdom during the 1980s, little attention was paid to the status of surface waters in the North York Moors (NYM). In this paper, we present sediment core data from a moorland pool in the NYM that provide a record of air pollution contamination and surface water acidification. The 41-cm-long core was divided into three lithostratigraphic units. The lower two comprise peaty soils and peats, respectively, that date to between approximately 8080 and 6740 cal. BP. The uppermost unit comprises peaty lake muds dating from between approximately ad 1790 and the present day (ad 2006). The lower two units contain pollen dominated by forest taxa, whereas the uppermost unit contains pollen indicative of open landscape conditions similar to those of the present. Heavy metal, spheroidal carbonaceous particle, mineral magnetics and stable isotope analysis of the upper sediments show clear evidence of contamination by air pollutants derived from fossil-fuel combustion over the last c. 150 years, and diatom analysis indicates that the naturally acidic pool became more acidic during the 20th century. We conclude that the exceptionally acidic surface waters of the pool at present (pH = c. 4.1) are the result of a long history of air pollution and not because of naturally acidic local conditions. We argue that the highly acidic surface waters elsewhere in the NYM are similarly acidified and that the lack of evidence of significant recovery from acidification, despite major reductions in the emissions of acidic gases that have taken place over the last c. 30 years, indicates the continuing influence of pollutant sulphur stored in catchment peats, a legacy of over 150 years of acid deposition.

Estimation of Age-Depth Relationships

Developments in Paleoenvironmental Research, 2012

An accurate and precise chronology is an essential pre-requisite for any palaeolimnological study... more An accurate and precise chronology is an essential pre-requisite for any palaeolimnological study. Chronologies give time-scales for events, and hence for rates for patterns and processes, and make it possible to compare and correlate events in different stratigraphical sequences. Palaeolimnology without chronology is history without dates. As radiocarbon dating is so widely used in palaeolimnology, this chapter focuses on 14 C dating, and its associated errors and the calibration of 14 C ages to calibrated 14 C ages. Calibration is ...

Hydroclimatic shifts in northeast Thailand during the last two millennia – the record of Lake Pa Kho

Quaternary Science Reviews, 2015

The Southeast Asian mainland is located in the central path of the Asian summer monsoon, a region... more The Southeast Asian mainland is located in the central path of the Asian summer monsoon, a region where paleoclimatic data are still sparse. Here we present a multi-proxy (TOC, C/N, d 13 C, biogenic silica, and XRF elemental data) study of a 1.5 m sediment/peat sequence from Lake Pa Kho, northeast Thailand, which is supported by 20 AMS 14 C ages. Hydroclimatic reconstructions for Pa Kho suggest a strengthened summer monsoon between BC 170eAD 370, AD 800e960, and after AD 1450; and a weakening of the summer monsoon between AD 370e800, and AD 1300e1450. Increased run-off and a higher nutrient supply after AD 1700 can be linked to agricultural intensification and land-use changes in the region. This study fills an important gap in data coverage with respect to summer monsoon variability over Southeast Asia during the past 2000 years and enables the mean position of the Intertropical Convergence Zone (ITCZ) to be inferred based on comparisons with other regional studies. Intervals of strengthened/weaker summer monsoon rainfall suggest that the mean position of the ITCZ was located as far north as 35 N between BC 170eAD 370 and AD 800e960, whereas it likely did not reach above 17 N during the drought intervals of AD 370e800 and AD 1300e1450. The spatial pattern of rainfall variation seems to have changed after AD 1450, when the inferred moisture history for Pa Kho indicates a more southerly location of the mean position of the summer ITCZ.

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Rapid climate change did not cause population collapse at the end of the European Bronze Age

by Katharina Becker, Maarten Blaauw, and Gill Plunkett

Proceedings of the National Academy of Sciences of the United States of America, Jan 2, 2014

The impact of rapid climate change on contemporary human populations is of global concern. To con... more The impact of rapid climate change on contemporary human populations is of global concern. To contextualize our understanding of human responses to rapid climate change it is necessary to examine the archeological record during past climate transitions. One episode of abrupt climate change has been correlated with societal collapse at the end of the northwestern European Bronze Age. We apply new methods to interrogate archeological and paleoclimate data for this transition in Ireland at a higher level of precision than has previously been possible. We analyze archeological (14)C dates to demonstrate dramatic population collapse and present high-precision proxy climate data, analyzed through Bayesian methods, to provide evidence for a rapid climatic transition at ca. 750 calibrated years B.C. Our results demonstrate that this climatic downturn did not initiate population collapse and highlight the nondeterministic nature of human responses to past climate change.

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Molecular analysis of the cytosolic and glycosomal glyceraldehyde-3-phosphate dehydrogenase in Leishmania mexicana

Molecular and biochemical parasitology, 1992

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity was detected in two cell compartments o... more Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity was detected in two cell compartments of Leishmania mexicana promastigotes. These activities could be attributed to two different isoenzymes, one residing in glycosomes, the other in the cytosol. We have cloned and sequenced the genes for both isoenzymes. The glycosomal enzyme is encoded by two tandemly linked genes of identical sequence and contains features frequently found in glycosomal enzymes: the presence of peptide insertions, a small carboxy-terminal extension with a potential glycosomal targeting signal (-SKM) and an excess of positively charged residues (net charge +7). Only one open reading frame was detected for the cytosolic enzyme. The amino acid sequences of the two proteins are only 55% identical. We discuss some evolutionary aspects of the observed organization of the GAPDH genes in the Trypanosomatidae and the role of the two isoenzymes in the metabolism of these organisms. The possibility to develop GAPDH-s...

Age models and the Younger Dryas Impact Hypothesis

by Jacquelyn Gill and Maarten Blaauw

Proceedings of the National Academy of Sciences, Aug 21, 2012

Israde-Alcántara et al.(1) drew on interpretations of a core from Lake Cuitzeo, Mexico to support... more Israde-Alcántara et al.(1) drew on interpretations of a core from Lake Cuitzeo, Mexico to support the Younger Dryas (YD) Impact Hypothesis. A key aspect of their study was identifying and dating the YD interval in the sediments. The authors stated that they recovered impact indicators from a 10-cm-thick zone dating to 12.9 kcal BP but provided no direct numerical age control or chronological uncertainties for this interval. Depending on the carbon sources, 14C ages of bulk lake sediment can be offset by several centuries (2). ...

Sea-level changes in Iceland and the influence of the North Atlantic Oscillation during the last half millennium

Quaternary Science Reviews, 2015

Climate and Peatlands

Changing Climates, Earth Systems and Society, 2010

Peatlands are an important natural archive for past climatic changes, primarily due to their sens... more Peatlands are an important natural archive for past climatic changes, primarily due to their sensitivity to changes in the water balance and the dating possibilities of peat sediments. In addition, peatlands are an important sink as well as potential source of greenhouse gases. The first part of this chapter discusses a range of well-established and novel proxies studied in peat cores (peat humification, macrofossils, testate amoebae, stomatal records from subfossil leaves, organic biomarkers and stable isotope ratios, aeolian sediment influx ...

14C wiggle-match dating of peat deposits

Disclaimer/Klachtenregeling Meent u dat de digitale beschikbaarstelling van bepaald materiaal inb... more Disclaimer/Klachtenregeling Meent u dat de digitale beschikbaarstelling van bepaald materiaal inbreuk maakt op enig recht dat u toekomt of uw (privacy)belangen schaadt, dan kunt u dit onderbouwd aan de Universiteitsbibliotheek laten weten. Bij een gegronde klacht zal de Universiteitsbibliotheek het materiaal ontoegankelijk maken en/of van de website verwijderen, dan wel samen met u bekijken hoe op een andere manier aan uw klacht tegemoet kan worden gekomen. Stuurt u hiervoor een e-mail naar: [email protected], of een brief naar: Bibliotheek van de Universiteit ...

14C wiggle-match dating and confidence intervals-outline

Tephra from andesitic Shiveluch volcano, Kamchatka, NW Pacific: chronology of explosive eruptions and geochemical fingerprinting of volcanic glass

International Journal of Earth Sciences, 2015

The ~16 ka long record of explosive eruptions from Shiveluch volcano (Kamchatka, NW 24 Pacific) i... more The ~16 ka long record of explosive eruptions from Shiveluch volcano (Kamchatka, NW 24 Pacific) is refined using geochemical fingerprinting of tephra and radiocarbon ages. Volcanic 25 glass from 77 prominent Holocene tephras and four Late Glacial tephra packages was analyzed 26 by electron microprobe. Eruption ages were estimated using 113 radiocarbon dates for proximal 27 tephra sequence. These radiocarbon dates were combined with 76 dates for regional Kamchatka 28 marker tephra layers into a single Bayesian framework taking into account the stratigraphic 29 ordering within and between the sites. As a result, we report ~1700 high-quality glass analyses 30 from Late Glacial-Holocene Shiveluch eruptions of known ages. These define the magmatic 31 evolution of the volcano and provide a reference for correlations with distal fall deposits. 32

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Half-precessional dynamics of monsoon rainfall near the East African Equator

Nature, 2009