PAGES Magazine articles

The PAGES Data Stewardship Scholarship program contributed to the development of an online database interface and a visualization tool of past sea level by the PALSEA working group.
 

The creation of reporting standards for sea-level proxies and the compilation of sea-level databases have been a central focus of the PALeo constraints on SEA level rise (PALSEA) working group (pastglobalchanges.org/palsea) since its inception (Düsterhus et al. 2016; Rovere and Dutton 2021). Over the last three years, these efforts came to fruition with two products. First, a global database of post-Last Glacial Maximum (LGM) sea-level index points was created within the Geographical variability of Holocene sea level (HOLSEA) project (Khan et al. 2019). Second, the creation of the World Atlas of Last Interglacial Shorelines (WALIS; Rovere et al. 2022) database, which includes sea-level proxies dating back to Marine Isotopic Stage (MIS) 5.

With the completion of these two databases, ideas started to arise concerning the feasibility of uniting them under a single interface and the availability of visualization and interfaces to allow for their exploration, and facilitate data query and download. With these ideas in mind, we submitted a proposal for a Data Stewardship Scholarship to PAGES. The proposal had two primary goals. The first was to implement the Holocene sea-level data standard format (Khan et al. 2019) into the interface built for the WALIS database (available here: alerovere.github.io/WALIS), eventually duplicating the database done within the HOLSEA project into WALIS. The second goal was to provide a visualization interface for the WALIS data, taking inspiration from the one already proposed for the HOLSEA database (Drechsel et al. 2021).

The first result of our work was the implementation of the HOLSEA data template into the WALIS database structure, including the online database interface. This work is now complete. As a result, any user logging into the WALIS online data insertion interface will not only be able to insert MIS 5 data, but will also find a series of tabs dedicated to the insertion of standardized Holocene data, including tables for radiocarbon, U-series, archaeological, and other age attribution methods. The Holocene part of the WALIS interface is currently undergoing beta testing, but is fully functional. After this phase, we plan to release a non-beta version of the interface, populated with the post-LGM data already in the HOLSEA database.

Figure 1: A screenshot of the WALIS Data Explorer application.

The second achievement of our work was the creation of a platform to query and analyze the data already included in WALIS. This work was done through an R Shiny App querying a simplified version of the WALIS database (i.e. including only the essential fields related to indicator type, paleo sea level and dating information). The app is currently in its 2.0 version. The code to run the app offline is available from Garzón and Rovere (2022), and the app is also accessible online at this link: warmcoasts.shinyapps.io/WALIS_Visualization/. The application is divided into three pages, which the user can navigate. On the first page, it is possible to filter the data by geographic selection, age, elevation, or indicator type. On the second page, the app allows the previously selected data to be downloaded in .csv format. Finally, on the third page, the app allows further fine-tuning of the data query by excluding specific index points and calculating an age/sea-level probability density graph using a Monte Carlo approach.

The results briefly described above represent a fundamental stepping stone towards increasing the wide availability and usability of paleo sea-level data. Our data and code are fully open access. Bug reports and suggestions on how to improve the current products and forks to the GitHub repositories linked to the published code versions are also welcome.

ACKNOWLEDGEMENTS

Thanks to the European Research Council under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 802414) for funding the World Atlas of Last Interglacial Shorelines database WALIS (Rovere et al. 2022).

affiliations

contact

Alessio Rovere: alessio.rovere@unive.it

references

Drechsel J et al. (2021) Quat Sci Rev 259: 106884

Düsterhus A et al. (2016) Clim Past 12: 911-921

Garzón S, Rovere A (2022) WALIS visualization interface. Zenodo

Khan NS et al. (2019) Quat Sci Rev 220: 359-371

Rovere A, Dutton A (2021) PAGES Mag 29: 18-20

Rovere A et al. (2022) WALIS - The World Atlas of Last Interglacial Shorelines (Version 1.0). Zenodo

The PAGES Data Stewardship Scholarship program allowed us to organize and archive multiple published peat-based paleoecological datasets, increasing their accesibility and visiblity via cross-platform linking.
 

Peatland archives

Peatlands are arguably the very first recognized paleoclimate archives. In the 19th century, the alternating dark and light layers from European peat deposits were interpreted as indications of warmer/drier and wetter/cooler conditions, respectively (Blytt 1876). These records of past climate change, which were based on plant macrofossils and pollen assemblages, led to the development of the first deglacial paleoclimate sequence: the Blytt-Sernander classification (Blytt 1876; Sernander 1908). Today, with thousands of peat profiles described and analyzed from every continent, peat-based paleoclimate work remains an active field of research.

Despite this long history and the large number of published studies, peat-based paleorecords remain somewhat underutilized. They are also seldom combined with those from other terrestrial archives, such as lakes, trees, and ice. Here we contend that peatland archives can offer complementary insights in Holocene paleoclimatology due to: (1) their global distribution, including regions where other terrestrial archives are rare; (2) their temporal coverage and resolution, which can offer decadal-scale Holocene reconstructions; and (3) their capacity to record changes in temperature, moisture source, or other climate components.

Figure 1: The Peatland Paleo Proxy Database as of 31 December 2022. It comprises 182 records from 101 cores. Orange = Neotoma Testate Amoebae Database; red = new proxy data contributions; blue = metadata only (for now). Modified from Melton et al. (2021).

Data aggregation and formatting

Over the past two years, C-PEAT Data Steward Nicole Sanderson has gathered as many peat-based paleoecological datasets as possible. She led a number of "peat proxy happy hour" sessions to engage with data owners and facilitate data transfer. She trained a couple of undergraduate researchers (Kendahl Hejl and Daniel Maraldo) in data formatting and quality control. She became a Neotoma data steward and has been actively discussing the Peatland dataset with Neotoma leaders. These efforts have paid off: 182 chronologically constrained paleorecords from 101 cores have recently been processed by our team (Fig. 1). Those cores are globally distributed, though most of them are located in the Northern Hemisphere. The dataset includes chronologically constrained testate amoebae, plant macrofossil, and geochemical records, as well as novel proxies such as biomarkers and stable isotopes (Fig. 1). Prior to our work, Neotoma only contained 18 peat-based paleorecords. The newly formatted records are being integrated on Neotoma and should be available sometime this year.

Current and future plans

The Peatland Paleo Proxy Database will be available for community use on Neotoma, and we aim to continue to expand its contents in order to improve process-based models. This new C-PEAT database will be used to assess ecosystem responses to past environmental drivers, including recovery from past abrupt changes in water table depth and temperature, as well as building carbon trajectories. We also aim to integrate the peat-based paleorecords with other terrestrial records (e.g. lake sediments, tree rings) in regional paleoclimate reconstructions. Our team is preparing a manuscript that describes the proxies included in the dataset and the methods used to format, synthesize, and analyze the paleo peatland records. Ultimately, we aim to link this dataset through LiPD (lipd.net).

ACKNOWLEDGEMENTS

We would like to thank Kendahl Hejl and Daniel Maraldo for their help building the database; Socorro Dominguez Vidana and Simon Goring for their technical support through Neotoma; the C-PEAT community for sharing their datasets and knowledge.

affiliations

contact

Julie Loisel: juloisel@hotmail.com

references

Blytt A (1876) Essay on the Immigration of the Norwegian flora during the alternating rainy and dry period. Alb. Cammermayer, Christiana, Oslo, 89 pp

Melton JR et al. (2021) A map of global peatland extent created using machine learning (Peat-ML). Zenodo

Sernander R (1908) Geol Fören Stockh Förh 30: 465-473

A major outcome for many PAGES Working Groups (WGs) (pastglobalchanges.org/science/current-wg) is their data-intensive synthesis product featuring a high level of data stewardship. These follow the long tradition in the paleoscience community of sharing and caring for the community’s data resources. PAGES WGs and the broader paleoscience community are fortunate in these efforts for the support of numerous discipline-specific data repositories and organizations. Their services help assure that our data are FAIR – findable, accessible, interoperable, and reusable (go-fair.org/fair-principles). We asked five international paleo data organizations to tell us about their latest activities of interest to the PAGES community.

PANGAEA

PANGAEA (Data Publisher for Earth & Environmental Sciences) (pangaea.de) is an open-access library for archiving, publishing, and disseminating georeferenced data from the Earth, environmental, and biodiversity sciences. It is operated jointly by the German research institutions MARUM in Bremen and AWI in Bremerhaven. Grown from its origins as a paleoclimate archive, PANGAEA now hosts >400000 datasets with more than 24 billion datapoints. Each dataset includes a data citation and a unique Digital Object Identifier (DOI). To add additional value to the archived datasets, PANGAEA now offers data-usage statistics where the number of web-based interactions with each dataset are tracked, and the impact of data sharing can be measured.

LinkedEarth

LinkedEarth (linked.earth) advances paleoclimate data standards and research. Datasets tied to LinkedEarth projects typically employ the Linked PaleoData (LiPD) structure. To improve searching across the breadth of LiPD datasets, the vocabulary for seven key paleoclimate variables has now been standardized on lipdverse.org, while aligning them to NOAA’s PaST Thesaurus (ncei.noaa.gov/products/paleoclimatology/paleoenvironmental-standard-terms-thesaurus). The open-source code ecosystem around LiPD is expanding, most notably with geoChronR (McKay et al. 2021), actR (github.com/LinkedEarth/actR) and Pyleoclim (Khider et al. 2022); new LiPD utilities in Python and analytical tools in R are forthcoming. Online workshops are training paleoscientists to use this budding research ecosystem, and an advanced in-person workshop will take place during summer 2023 in California, USA.

Figure 1: The paleoscience community is fortunate to be supported by discipline-specific data repositories and organizations which help assure that our data are FAIR – findable, accessible, interoperable, and reusable.

EuroClimHist

EuroClimHist (euroclimhist.unibe.ch/en) is a database of historical climate data based on documentary and early instrumental evidence augmented by proxy records from natural archives. It is operated by the Institute of History, Department of Social Economic and Environmental History, and the Oeschger Centre for Climate Change Research at the University of Bern, Switzerland. The volume of data that is publicly accessible has recently increased. Two larger bodies of Swiss weather observations, including large phenological data on a nearly daily basis, have been included (Rudolf Salis-Marschlins, 1781–1800; Jakob Hänni 1839–1870). In collaboration with the World Glacier Monitoring Service (WGMS), a large number of historical paintings, drawings and early photographs of Swiss glaciers have recently been entered into the database. An upcoming project will focus on glaciers from the western Alps and Norway.

World Data Service for Paleoclimatology

The World Data Service for Paleoclimatology (ncei.noaa.gov/products/paleoclimatology), hosted by National Oceanic and Atmospheric Administration (NOAA), has now completed minting new DOIs for the backlog of >10 000 individual datasets that have been contributed over the past three decades. The NOAA Paleoclimatology now routinely assigns DOIs to new contributions. The DOIs are available on each landing page and in metadata files (see this example landing page). Instructions for new submissions, along with requirements and timelines for obtaining a dataset DOI, are being updated and will be announced via the Paleoclimate List when available. Dataset DOIs are important to cite along with publications to give full credit to data generators.

Neotoma

The Neotoma Paleoecology Database (neotomadb.org) features an improved website with access to 31,900 datasets, comprising 10.7 million datapoints from 19,100 sites. Neotoma is working closely with LinkedEarth to build import–export capabilities with the popular LiPD format. Data mobilization campaigns for fossil pollen data are underway, particularly in Africa, the Indo-Pacific, and Latin America. ª new NSF-funded project is enhancing Neotoma support for both FAIR and CARE (Collective benefit, Authority to control, Responsibility and Ethics) data standards, in partnership with other paleodata resources. A new project is developing controlled vocabulary for lipid biomarker variables, with support from Belmont Forum, and another is partnering with a coalition of labs to support the curation of sedimentary (ancient) DNA datasets. Online and in-person educational workshops are planned, including at INQUA2023.

Acknowledgements

We thank Julien Emile-Geay, Frank Oliver Gloeckner, Carrie Morrill, Christian Rohr, and John (Jack) Williams for their responses.

affiliations

1School of Earth and Sustainability, Northern Arizona University, Flagstaff, USA
2MARUM Center for Marine Environmental Sciences, University of Bremen, Germany
 

contact

Darrell Kaufman: Darrell.Kaufman@nau.edu

References

Khider D et al. (2022) Paleoceanogr Paleoclimatol 37(10): e2022PA004509

McKay NP et al. (2021) Geochron 3(1): 149-169

The workshop on Past Socio–Environmental Systems (PASES) took place in La Serena, Chile (pastglobalchanges.org/calendar/26972) and was organized by the early-career networks of PAGES (Past Global Changes) and INQUA (International Union for Quaternary Science).

The aim of the workshop was to provide a common platform for early-career researchers (ECRs) working on past climate–environment–cultural changes. The scientific essence of the meeting was to offer the opportunity to discuss different proxies and perspectives, as reflected by the titles of the presented talks (Fig. 1). An interdisciplinary approach is necessary for understanding socio–environmental systems: the complexity of the causal relations between the natural and human-driven forcings can be grasped by acquiring data and methods from different disciplines and interpreting them using a multiple working hypotheses framework.

Figure 1: The diverse range of topics from the presentation titles at the PASES workshop represented in a word cloud.

The workshop was held after a two-year postponement due to the COVID-19 pandemic, with the participation of 20 ECRs and four keynote speakers from 10 different countries from four continents. The meeting was held at the Archaeological Museum of La Serena, and coordinated by the Center for Advanced Studies in Arid Zones (CEAZA). The workshop consisted of three days of oral presentations, and included breakout activities, outreach talks involving high-school students and local communities, and a one-day field excursion.

Presentations were organized into three thematic sessions which provided scientific foci. The session on "Novel techniques in past human–environmental couplings" tackled recent advances in methods and proxies from sedimentary sequences for improving our understanding of human impacts on ecosystems. These methods range from functional approaches of biological proxies and biomarkers, to archaeological heritage conservation. During the session on "Socio–Environmental Systems in the Anthropocene", researchers presented provocative talks, such as the social component of the term "Anthropocene", and socio–economic responses to climate change in past archaeological societies. Finally, the "Synthesizing archaeological, paleoclimatic and paleoecological records" session presented a wide range of practical ways to integrate diverse records. These included paleo-monsoon dynamics and links with socio–cultural changes in India, and Late Quaternary extinction of megafauna in South America. Talks also revealed the importance of numerical approaches widely used across disciplines (e.g. machine learning, species distribution models) to decipher the dynamics of human–environmental relationships.

During the breakout activities, participants were divided into three groups to discuss the overarching topic of resilience of past climate–environment–cultural systems. As part of the original PASES registration process, we asked interested people to list the most urgent questions related to the workshop topic. Over 150 questions were proposed at that stage, and a few of them were selected as the starting point for group discussions in La Serena. The questions revolved around types of proxies and archives, semantic barriers, and analytical frameworks in past socio–environmental systems.

The rich cultural heritage of the PASES venue, the Coquimbo region, was visited during the mid-workshop excursion. Participants learned from an enthusiastic team of local guides how and when humans interacted with the environment during historical times. The visit also included an exploration of archaeological landmarks of the Guanaqueros city. Led by Dr. Carola Flores, associate researcher at CEAZA and PASES keynote speaker, participants walked through the Valle de el Encanto and got to know its cultural heritage, characterized by enigmatic rock art and its "piedra tacitas" (human-carved rocks, of which the origins and function are still debated).

Summary and ways forward

Organizing the PASES workshop has been both challenging and rewarding, and has allowed us to build a network for long-term collaborations. Outputs of the breakout activities, and lessons learned during the workshop planning and organization, were incorporated into this Past Global Changes Magazine special issue (p. 38-39).

affiliations

Xavier Benito (Marine and Continental Waters Programme, Institute of Agrifood Technology and Research, IRTA, La Ràpita, Spain)
Ignacio Jara (Universidad de Tarapacá, Arica, Chile)
Giorgia Camperio (ETH Zürich and Eawag, Switzerland)
Fernanda Charqueño (CENAC-PNNH-CONICET, Bariloche, Argentina)
Kim Davies (Bournemouth University, Fern Barrow, Poole, Dorset, UK)
Francesca Ferrario (Università dell’Insubria, Como, Italy)
Aliyu Adamu Isa (Ahmadu Bello University, Zaria, Nigeria)
Anna-Marie Klamt (University of Southern Denmark, Odense, Denmark)
Michela Mariani (University of Nottingham, Nottingham, UK)
Nivedita Mehrotra (Birbal Sahni Institute of Palaeosciences, Uttar Pradesh, India)
Victor Merino (Universidad Nacional de Mar del Plata, Mar del Plata, Argentina)
Emuobosa Akpo Orijemie (University of Ibadan, Ibadan, Nigeria)

Xavier Benito: xavier.benito.granell@gmail.com

Understanding the evolution of Quaternary glacial cycles has been a long-standing question in paleoclimate science. In the Early Pleistocene, glacial cycles appear symmetric with smaller ice volumes and a period of 41 kyr. Over the course of the Middle Pleistocene Transition (MPT; ~1.25–0.65 Myr BP), glacial cycles became longer (~100 kyr), stronger, and more "saw-tooth" shaped (Fig. 1a). The workshop aimed to examine differences between interglacials of the 41-kyr and 100-kyr worlds and assess hypotheses for the MPT. The meeting, held at Lamont-Doherty Earth Observatory of Columbia University, was the third meeting of QUIGS (pastglobalchanges.org/quigs) Phase 2, attended by 49 participants (27 in person, 22 online) from 11 countries, including 17 early-career researchers (ECRs).

Figure 1: (A) LR04 benthic δ18O stack (Lisiecki and Raymo 2005), showing the evolution of glacial cycles over the last 3 Myr. (B) Schematic of the types of drivers and changes invoked in different MPT hypotheses.

Structure and duration of the 41-kyr world interglacials

The traditional view of the 41-kyr world is that ice-volume changes reflect a more linear response to obliquity forcing, often producing interglacial shapes resembling isosceles triangles. This was challenged by the emergence of new high-resolution records from the Iberian Margin (David Hodell, Joan Grimalt, Chronis Tzedakis), revealing a variety of shapes, durations, and intensities. Modeling by David Hodell, and by Yasuto Watanabe and Ayako Abe-Ouchi, showed that the phasing of precession and obliquity influences the structure and duration of interglacials of the 41-kyr world, as well as the timing of glacial terminations and inceptions. Discussions underscored the importance of comparing ice-sheet model results with glacial-geologic data to improve our understanding of the structure of 41-kyr cycles.

Basic questions remain about the MPT

The second focus of the meeting centered on our understanding of the driver(s) of the MPT. Presentations considered whether the MPT was caused by shorter- or longer-term changes, or whether the transition resulted from a threshold response in the ocean-atmosphere system to a more gradual forcing. Hypotheses included: 1) Regolith removal by land ice that changed ice-sheet dynamics and led to the emergence of larger ice sheets; the larger ice sheets, in turn, led to the skipping of insolation cycles and the appearance of ~100-kyr glacial cycles (Clark and Pollard 1998); 2) Long-term cooling that led to a gradual rise in the insolation threshold required for deglaciation and, in turn, to an increase of skipped obliquity cycles; the emergence of longer glacials then allowed the accumulation of larger ice sheets (Tzedakis et al. 2017); 3) The combined effect of long-term cooling driven by CO2 drawdown and regolith removal (Willeit et al. 2019); 4) Antarctic ice-sheet growth (from land-based to marine-based margins), which changed the structure of deep ocean circulation and carbon storage; the resulting atmospheric CO2 drawdown led to the increase in Northern Hemisphere ice sheets and the 100-kyr cycle (e.g. Farmer et al. 2019; Ford and Raymo 2020; Peña and Goldstein 2014); 5) Strengthening Atlantic Inflow into the Nordic Seas enhanced poleward moisture transport and promoted the growth of larger ice sheets which spread southwards and resulted in a shift from ~41 to ~100 kyr cyclicity (Barker et al. 2021). However, the ultimate trigger for many of these hypotheses remains elusive (Fig. 1b).

The discussions highlighted the need for more proxy and atmospheric greenhouse gas data, but also a critical evaluation of existing proxies and records. For instance, Peter Clark challenged the interpretation of benthic δ18O as primarily indicating a change in ice volume across the MPT and suggested that much of the δ18O change across the MPT was driven by ocean cooling. Sophie Hines challenged the traditional interpretation of εNd as predominantly indicating changes in water mass geometry (and thus deep-ocean circulation). Using new high-resolution εNd data from the Cape Basin, she suggested a more nuanced interpretation of εNd that reflects both changes in deep-ocean circulation and endmember composition across the MPT. Reconciling records using various tracers of deep-ocean circulation (particularly δ13C and εNd) will help narrow the range of MPT hypotheses.

The next QUIGS workshop ("Interglacial Intensity") will take place in Grenoble, France, in September 2023 (pastglobalchanges.org/calendar/137088).

aCKNOWLEDGEMENTS

We thank all the participants who engaged in this workshop, and PAGES and the LDEO Climate Center for their support.

affiliations

contact

Chronis Tzedakis: p.c.tzedakis@ucl.ac.uk

REFERENCES

Barker S et al. (2021) Paleoceanogr Paleoclimatol 36: e2020PA004200

Clark PU, Pollard D (1998) Paleoceanogr 13: 1-9

Farmer JR et al. (2019) Nat Geosci 12: 355-360

Ford HL, Raymo ME (2020) Geology 48: 113-117

Lisiecki LE, Raymo ME (2005) Paleoceanogr 20: PA1071

Peña LD, Goldstein SL (2014) Science 345: 318-322

Tzedakis PC et al. (2017) Nature 542: 427-432

Willeit M et al. (2019) Sci Adv 5: eaav7337

International Partnerships in Ice Cores Science (IPICS) 3rd Open Science Conference & Ice Core Young Scientist (ICYS) meeting, Crans-Montana, Switzerland, 2–7 October 2022

With this background, the international ice-core science community assembled for its third Open Science Conference (OSC) (pastglobalchanges.org/calendar/26967) in Crans-Montana, a ski resort above the Rhone Valley in Switzerland, only about 50 km from the Colle Gnifetti. The OSC brought together ice-core scientists from 20 countries working on the Greenland and Antarctic ice sheets as well as high-altitude glaciers; hence the theme of the conference was chosen to be "Ice Core Science at the three Poles." Also, a few intrepid specialists from other paleoclimate science areas attended the conference. The conference had been initially planned for 2020 but was postponed twice due to the COVID-19 pandemic. It could finally take place in fall 2022, allowing scientists from all regions of the globe to attend.

Of course, the authors of this report, who were also the conference chairs, are biased, but it was worth the wait! With 270 participants on site, and about 20 joining online, it was the largest IPICS OSC ever, and spirits were extremely high, showing that ice-core science is thriving and more important than ever. Latest proxy developments in ice-core science and from other areas of paleoclimate research, new ice-core drilling techniques, new high-resolution ice-core records, and reports from, and plans for new ice-core projects (ranging from rescuing high-altitude glacier archives to securing the oldest ice on Earth) were presented in lectures from invited speakers, science talks and several poster sessions, with a high number of contributions. Moreover, the OSC was preceded by the traditional young scientist meeting organized by the ice-core early-career network ICYS, and attended by more than 130 early-career scientists. This meeting offered insights into additional aspects of research today, and instructed the attendees in various facets of science communication and research career development.

Certainly, the perfect organization by conference manager Doris Bühler from the Paul Scherrer Institute, the warm welcome and support by the conference center, Le Régent, and the typical Swiss hospitality, with both light and cheesy food, kept spirits and energy levels high for the entire week. Hands-on experience in glacier loss was provided by an excursion to the Great Aletsch Glacier on Wednesday afternoon, while a highlight was certainly the transdisciplinary theater production (initiated by Margit Schwikowski and author and theatre director Sabine Harbeke) called "Fleeting ice - news of tomorrow" (fluechtigeseis.ch) which took place on Tuesday evening. This theater performance illustrated the waning of ice due to climate change in sounds, enactment, and music, and was acknowledged by the IPICS scientists with standing ovations. A post-conference excursion to the Research Station Gornergrat at the foot of the Colle Gnifetti completed the program.

Of course, all this would not have been possible without a large number of sponsors (indico.psi.ch/event/6697/); PAGES was one of them, providing generous support for young researchers from low- to middle-income countries. Given the success of the conference and the outstanding contributions by many early-career scientists, ice-core science itself does not seem to be at risk (see also Fig. 1). We look forward to the next IPICS OSC to be held in 2026!

affiliations

contact

Hubertus Fischer: hubertus.fischer@unibe.ch

REFERENCES

Osman M et al. (2022) A half century of partnerships in ice core sciences: evidence of progress and areas for improvement. 3rd IPICS Open Science Conference, Crans-Montana, Switzerland

The event was organized in collaboration with the International Association of Limnogeologists (IAL) and the International Paleolimnology Association (IPA). The conference was attended by almost 300 people from 31 countries, including seven in South America.

The goal of the IAL–IPA 2022 conference (pastglobalchanges.org/calendar/27009) was to gather research on lake systems from multiple perspectives, with a focus on both the sediment record from the Earth system archive and the social and cultural memory of the territory. The conference aimed to bridge the gap between a broad range of disciplines that work within the overarching theme of Earth system and climate–environment–cultural changes.

Figure 1: IAL-IPA 2022 conference logo.

The conference was made up of oral and poster presentations about diverse scientific themes and aspects. The general and focus sessions addressed topics such as human traces in the aquatic sedimentary record, the sensitivity of high-altitude aquatic ecosystems, lake biodiversity changes through time and space, and paleoenvironment and paleoclimate records from long-lived lakes. Novel approaches such as molecular application and perspectives on environmental systems, and integration of process models into paleolimnological methods, were topics particularly well received by the audience, especially by young scientists starting out in their careers in paleoscience. Additionally, the program included special sessions about the value of outreach, education, equality, diversity, and inclusion in the field of lake studies, and on the challenge of communicating science to the public.

Every day, invited keynote speakers from the Earth, Biological and Social Sciences presented a wide variety of topics in plenary sessions. Plenary talks were gender balanced, including two female researchers from Chile (Ana Abarzúa, Universidad Austral de Chile) and Argentina (Beatriz Modenutti, Universidad Nacional del Comahue). Esteban Castro, an Argentinean specialist in the field of social sciences, also attended the meeting and spoke about the serious problem caused by human failures behind the devastating water-related risks, threats and disasters suffered worldwide in recent years, and the expected worsening of this situation in many areas of the world.

Pre-conference virtual short courses were organized for students and early-career researchers (ECRs): "The Neotoma Paleoecology Database: How to Access, Use and Contribute Data" (Joy Hobbs, Don Charles and team), "An Introduction to GIS" (Julio Lancelotti) and "Multivariate Statistics for Paleoenvironmental Sciences" (Alex Correa-Metrio). Mid-conference social activities, including a workshop on landscape illustration, walking tours, and a local beer experience fostered a friendly atmosphere for participants. Two different one-day excursions took place on 2 December. During the meeting, Professor Daniel Ariztegui from the University of Geneva was awarded with the IAL W.H. Bradley Medal, which is given to a limnogeologist who is outstanding in their field. The IPA Rick Battarbee Lifetime Achievement Awards were given to Mark Brenner, Steve Juggins, Anson Mackay, Nora Maidana, and John Smol.

The congress was closed by a general IAL-IPA assembly, followed by a gala dinner. The next IAL-IPA Conference, as announced in the general assembly, will be held in 2025 in Savoy, France.

Finally, we would like to thank PAGES for encouraging the participation of ECRs by providing financial support to almost 50 young scientists from different parts of the world.

affiliations

contact

J. Massaferro: jmassaferro@comahue-conicet.gob.ar

What is a human trace and how does it manifest in the environment? Since its inception in 2021, members of the Human Traces working group (WG) (pastglobalchanges.org/human-traces) have been exploring possible answers to this complicated and multifaceted question through a series of online workshops and lectures (recordings are available on our YouTube channel here: shorturl.at/dghW7).

In December, we continued these discussions at our first in-person workshop which was held in Bariloche, Argentina, following our Human Traces in the aquatic sedimentary record session on 3 December at the International Association of Limnogeology and International Paleolimnology Association (IAL-IPA) 2022 Joint Meeting (pastglobalchanges.org/calendar/129293).

The workshop was attended by 20 people from 11 countries, including nine early–career researchers (ECRs), with strong representation from Latin America. This was the occasion to establish a subgroup made up of members from this region, with the aim of crafting an in-depth regional review of human traces in Central and South America (Fig. 1).

Figure 1: Human Traces in Latin America identified in different biogeographical areas: Mesoamerica (yellow circle) including México and Central America; the Andes (gray circle) including the western part of Ecuador, Peru, Argentina, and Chile; the Pampas (red circle) including Central Argentina and Uruguay; Patagonia (blue circle) including southern Argentina and Chile; and Amazonia (purple circle) including most of Brazil, and part of Colombia, Venezuela, Peru and Bolivia. The time intervals of interest for the Human Traces WG are: Pre-columbian (before 1500 CE), European colonization (between 1500 and 1900 CE) and modern times (1900 CE up to present).

This subgroup is open to anyone who has an interest, and can contribute to, the topic. It is coordinated by Human Traces WG member Julieta Massaferro (jmassaferro@comahue-conicet.gob.ar), who can provide further information about the initiative for those interested.

Attendees at the workshop also discussed plans to start working on a synthesis on the subject of reservoirs and the long-term development of anthropohydrocosms (a human-made body of water) (Saulnier-Talbot and Lavoie 2018) as agents of human traces in the environment.

The tentative objective of this subgroup would be to assess the use of the paleolimnological approach to evaluate and quantify anthropogenic impacts on the environment through time, via the creation and modification of aquatic ecosystems. This project is co-led by ECR Léo Chassiot (leo.chassiot.1@ulaval.ca) and WG coordinating member Émilie Saulnier-Talbot (emilie.saulnier-talbot@bio.ulaval.ca). All paleoscientists interested in participating are welcome to get in touch.

Finally, the workshop was also the occasion to update participants on the progress made by the lead proxy subgroup, who have already held an online workshop to develop a synthesis of lead as an indicator of human traces in sedimentary archives.

ECR Madeleine Moyle (maddy.moyle@liverpool.ac.uk) and WG coordinating member John Boyle (jfb@liverpool.ac.uk) are co-leaders of this subgroup. They held an online meeting in April 2023 and are planning an in-person meeting this year, with a provisional date in September 2023.

The group is currently collecting data and is working closely with the Neotoma community on developing a database for geochemical archives in lake sediments. If you have anything to contribute, please contact the co-leaders of the Human Traces WG (pastglobalchanges.org/science/wg/human-traces/people). For regular updates about the Human Traces WG and its activities sign up to the mailing list (listserv.unibe.ch/mailman/listinfo/human-traces.pages).

affiliations

contact

Madeleine Moyle: m.moyle@liv.ac.uk

references

Saulnier-Talbot É and Lavoie I (2018) Anthropocene 23: 29-42

Figure 1: Representation of the magnitude of offsets and uncertainties in boron-CO2 estimates in the literature. Future emission scenarios are depicted with lines (IPCC 2021).

The importance of the boron isotope CO2 proxy

Amongst proxies for past atmospheric CO2 reconstruction, boron isotopes have become one of the most well-established, and are increasingly recognized for their accuracy and precision (IPCC 2021). Boron isotopes have gained this reputation for two reasons: firstly, they can replicate atmospheric CO2 during periods where ice-core estimates are available for comparison (Chalk et al. 2017), and secondly, their methodological basis is now reproducible and accurate by different laboratories (Gutjahr et al. 2020) based on community-led efforts to standardize analytical data generation. As yet, however, no analogous consensus has emerged on how we obtain CO2 estimates from boron isotopes. This area has seen a great many advances: in constraining and calculating seawater temperature and boron isotope composition, in deriving the necessary second carbonate system parameter, in how "vital effects" (i.e. biological modifications to the proxy) are accounted for, in dealing with changing seawater chemistry, and in how uncertainties are measured and propagated. As a result of this rapidly changing landscape, many studies are now mutually inconsistent in their guiding assumptions, and old data need updating with new methods, or even replacing or omitting where their inclusion no longer adds value.

A community-led consensus

To address these issues, we organized a virtual series of workshops between 2021 and 2022, culminating in a PAGES-supported workshop in Bergen, Norway, in September 2022. Our aims were to critically evaluate the approaches used, discuss how to expand the horizons of the boron-CO2 proxy, and build an internally consistent compilation of long-term pH and CO2 change that provides reliable, accurate and future-proof (where possible) constraints on past climate. Several important observations were developed over the course of these workshops, most notably that:

1) although not the main cause of inconsistent CO2 values in the literature, differing data processing scripts utilized by the community can cause reconstructions to diverge over periods of changing seawater composition;

2) a consistent approach to "vital effects" is required to integrate different datasets; and

3) there are critical time periods where data density is poor, such as the Paleocene, Oligocene, and Miocene.

Already, these workshops have streamlined cross-platform, community-tested scripts, incorporating recent developments in carbonate and seawater chemistry (Hain et al. 2015). We interrogated the unknowns of the proxy and best-practice approaches, for example the treatment of "vital effects", impact of seawater major ion chemistry, and assumptions about the auxiliary data required for converting pH to CO2. Two periods – the Miocene and the Eocene – were identified as having the largest discrepancies in CO2 estimates, thus providing effective test cases for developing consensus in boron-derived CO2 processing.

Alongside resolving internal inconsistencies within the community, our workshop aimed to look outwards, and foster exchange with the broader community, toward data-model integrations and constraining past carbon cycle-climate interactions and Earth’s climate sensitivity. Finally, we demonstrated the need for, and sowed the seeds of, closer collaboration and coordination within the international boron isotope community. Results of these efforts arising from the online and in-person PAGES meetings are already appearing in a dedicated special issue of Paleoceanography and Paleoclimatology, which is open for submissions. Results will also be synthesized in a forthcoming boron-CO2 compilation paper.

affiliations

contact

Eleni Anagnostou: eanagnostou@geomar.de

REFERENCES

Chalk TB et al. (2017) Proc Natl Acad Sci 114: 13114-13119

Foster GL et al. (2017) Nat Comm 8: 14845

Gutjahr M et al. (2020) Geostand Geoanal Res 41: 59-75

Hain MP et al. (2015) Glob Biogeochem Cycles 29(5): 517-533

Hönisch B (2021) Paleo-CO2 data archive (Version 1). Zenodo

IPCC (2021) Climate Change 2021: The Physical Science Basis. In: Masson-Delmotte V et al. (Eds). Cambridge University Press, 2391 pp

Rae JWB et al. (2021) Annu Rev Earth Planet Sci 49: 609-641

Bergen, Norway, 3 September 2022

Workshop motivation and aim

Deoxygenation is a pressing problem in the world’s oceans, impacting global biogeochemical cycles and marine ecosystems. Oxygen time series only span decades (a maximum of ~60 years at their longest), and touch upon a small subset of at-risk ecosystems. The use of paleo-oxygen proxies allows us to explore long-term oxygen trends, including the scope of natural variability and response to warming, and ultimately to inform model simulations and projections.

While interest in paleo-oxygen reconstructions has been rapidly growing, our current proxy landscape often poses limitations. There are multiple established and emergent proxies available, but their scope, limitations, and relation to one another are often poorly constrained.

The aim of the PLO2P (Proxies for Low Oxygen Paleoenvironments) Workshop in Bergen, Norway, in September 2022 (pastglobalchanges.org/calendar/128968), was to convene and build a community of scientists working on paleo-oxygen proxies to begin to address these limitations in a way that was accessible to the larger paleoceanographic community, and collectively map a way forward. Together we decided to begin a review of the state-of-the-art in established and emergent Cenozoic paleoceanographic proxies used for assessing seawater oxygen concentrations.

Figure 1: Schematic illustration, made by Katrina Nilsson-Kerr, featuring the various paleo-oxygen proxies within a marine sediment core that were discussed during the meeting and will be covered in the review paper.

Workshop structure

The workshop was held in a hybrid mode to allow for broader participation, with a total of 33 participants. Hybrid mode was particularly useful because some in-person participants had to self-isolate due to COVID-19, but were still able to access the meeting from their conference accommodation. There was a focus on inclusion of early-career researchers (ECRs) actively working with paleo-oxygenation proxies. In total, 19 ECRs attended the workshop, and were also well-represented among the organizing committee (Dharma Reyes Macaya, Katrina Nilsson-Kerr, Jorge Cardich). Five ECRs received funding from PAGES to support their in-person participation at the workshop.

Following introductions, participants joined two (a morning and an afternoon) breakout sessions, based on the proxies they wished to focus on (see Figure 1 for a schematic). Established proxies for oxygen reconstructions include sedimentary features, like laminations, planktic and benthic foraminifera assemblages, sedimentary redox trace elements, and bulk nitrogen isotopes. Emerging paleo-oxygen proxies include the morphology of benthic and planktic foraminifera, benthic foraminifera carbon isotope gradients, benthic and planktic foraminifera trace elements, planktic foraminifera bound nitrogen isotopes, and biomarkers. Many of the proxies may be used for bottom or pore water oxygenations, but, increasingly, proxies are being developed to reconstruct water column oxygen concentrations. Multiple experts on each proxy type were invited to lead and moderate the breakout group sessions. Every section was tasked with identifying recent developments, limitations, and current questions of their proxy type. For example, several sessions identified the need to reconcile proxies developed in restricted basins, with open ocean settings, and vice versa.

Outcomes

The group identified several areas for development. Most proxies are currently only applicable to very low oxygen environments. Moreover, most proxies are qualitative rather than quantitative in nature, but steps are being taken to develop proxies more quantitatively and provide error assessments. The group concluded that more robust assessment of past seawater oxygen concentrations require multi-proxy analyses.

We are formalising our review in a paper using the framework established in the workshop (submission to Biogeosciences in August 2023). That review is now well underway, and the number of contributing authors has increased to include authors beyond the initial workshop participants who are experts on some of the proxies included in the review. The review will include descriptions of use and recommendations for best practices by proxy type, guiding those wishing to use paleo-oxygen proxies, and a roadmap for continuing expansion of this field.

Finally, we introduced the idea of forming a working group during the workshop, and are actively working on a PAGES working group proposal for past seawater oxygen assessments through paleoceanographic reconstructions and modeling.

Acknowledgements

The workshop was co-sponsored by a UKRI FLF (MR/S034293/1) to BH.

affiliations

contact

Babette Hoogakker: b.hoogakker@hw.ac.uk