PAGES Magazine articles

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: show mail address

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.granellgmail.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: show mail address

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.fischerunibe.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: show mail address

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 (show mail address), 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 (show mail address) and WG coordinating member Émilie Saulnier-Talbot (show mail address). 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 (show mail address) and WG coordinating member John Boyle (show mail address) 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.moyleliv.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: eanagnostougeomar.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.hoogakkerhw.ac.uk

The ACME (Arctic Cryosphere Change and Coastal Marine Ecosystems; pastglobalchanges.org/acme) working group held its second workshop from 14–16 November 2022 at the Geological Survey of Denmark and Greenland (GEUS), in Copenhagen, Denmark. The workshop "Numerical ecology and time series analysis of marine proxy data" focused on statistical treatment of sedimentary proxy data and correct data handling as a foundation for accurate and robust paleoenvironmental and paleoclimatic reconstructions.

The overarching aim of ACME is to assess and refine available marine proxies in the Arctic coastal zone. A particular focus is placed on the techniques (field, analytical and numerical) and the quality of data, on the establishment of new community-driven protocols and on the training of early-career researchers (ECRs). The ACME Community Survey, carried out in late 2020, revealed that nearly half (45% of respondents) of the community consider that we do not, yet, have adequate methods for the quantitative determination of widely reconstructed environmental parameters, and over half (65% of respondents) consider that we do not currently have an adequate understanding of proxy behavior (Heikkilä et al. 2022). There seems to be a misalignment between the statistical knowledge of method users and method developers, which often precludes a more critical evaluation of the approaches used by the community.

This ACME workshop aimed to overcome this challenge by inviting an expert in numerical ecology with extensive experience in paleoecological proxy data and paleo-communities. Dr. Gavin Simpson, professor in applied biometrics at Aarhus University, Denmark, has over two decades of experience in quantitative environmental science across timescales, with a specific focus on aquatic environments and complex environmental problems. He has developed several R packages, and worked with large databases (e.g. Neotoma).

During the workshop, Dr. Simpson shared his knowledge, discussed possibilities and common pitfalls related to numerical approaches in paleoecology, and here, specifically, coastal paleoceanography. In addition, hands-on tutorials and computer exercises using representative coastal data sets were provided, to serve as a real-world training, especially directed at ECRs with some prior experience in using R software.

The workshop included 22 participants from eight different countries (Canada, Denmark, Finland, Iceland, Italy, Poland, Portugal and UK) of which 16 (73%) were ECRs. The majority of participants were female (68% female/ 32% male). Altogether, the participants covered a broad range of proxy methods, ranging from different groups of microfossils (diatoms, dinoflagellate cysts, foraminifera), biogeochemical markers, and environmental DNA (eDNA). The participants unanimously expressed the wish to become more familiar with data handling, visualization, and numerical methods used to interpret and reconstruct past climate and environmental changes based on proxy data.

The first day of the workshop (14 November) was dedicated to an overview of R studio and data handling in R, including the Tidyverse collection of packages, importing data, data wrangling, and visualization. At the end of the first day, Dr. Nicolas van Nieuwenhove (University of New Brunswick, Canada) gave an invited lecture on the Neotoma database and efforts to migrate the widely used Northern Hemisphere modern dinoflagellate cyst reference dataset there. He provided a historical perspective on the use of dinoflagellate cysts in Northern Hemisphere paleoceanography and an overview of the current practices using quantitative methods.

The second day of the workshop was dedicated to multivariate ordination methods (unconstrained and constrained ordination), generalized additive models (GAMs), and their use in ecological modeling, in particular to identify rates and periods of change in time series. The participants had the opportunity to work with their own datasets and discuss the outcome of the analyses.

Figure 1: Diagram showing the workflow in data science. Image credit: Gavin Simpson and Steve Juggins.

The third and last day of the workshop was dedicated to quantitative paleoenvironmental reconstruction methods and the assessment of reconstruction validity and accuracy. The different types of paleoecological transfer functions were covered, including weighted averaging-based regressions and the modern analogues technique, as well as evaluation of model performance and diagnostics.

Key take home messages from this workshop were the importance of carefully considering study and sampling design ahead of numerical analyses (e.g. number of samples, replicates, environmental gradients), and the importance of critically assessing proxy data (e.g. what are species responding to?, what processes affect the formation and preservation of this proxy?) beyond statistical and method knowledge.

All the course materials and tutorials are publicly available at: github.com/gavinsimpson/acme-stats

affiliations

contact

Sofia Ribeiro: srigeus.dk

REFERENCES

Heikkilä M et al. (2022) Anthropocene 37: 100319

PlioMioVAR workshop, Leeds, UK, and online, 24–26 August 2022

(1) From PlioVAR to PlioMioVAR

As our initial phase of the PlioVAR database is nearing completion (McClymont et al. 2020), built as part of the former PAGES PlioVAR WG, our ongoing aim is to expand the dataset spatially and temporally. The first phase of PlioVAR focused on marine records due to the specific age-model constraints for data-model comparisons. Consequently, terrestrial archives of vegetation and precipitation were excluded from the initial work. Workshop participants identified updating the terrestrial records as a strategic aim of the next PlioMioVAR objectives. The Miocene arm of the working group met in January 2023, and has a series of planned hackathons before a hybrid meeting in June 2023 (pastglobalchanges.org/calendar/129302) to work on organizing paleoceanographic records.

(2) From PlioMIP2 to PlioMIP3

The second phase of the Pliocene Model Intercomparison Project (PlioMIP2) is reaching its conclusion, with meeting participants presenting various paleoclimate modeling studies covering topics such as the quantification of Earth’s Climate Sensitivity, patterns of atmospheric and oceanic circulation, polar amplification, climate extremes and assessments of model performance vis-à-vis marine and terrestrial proxy data (Fig. 1). In addition, draft science plans for PlioMIP3 were presented, discussed, and endorsed by participants both from the modeling and data communities. Future modeling directions discussed include the expansion of the temporal remit of PlioMIP into the Early Pliocene, enabling a comparison between Late and Early Pliocene climate states, and building one half of a scientific bridge that will eventually facilitate research collaboration between the PlioMIP and MioMIP projects.

Figure 1: Figure from McClymont et al. (2020) showing the site locations used in the PlioVAR synthesis. Sea-surface temperature proxies are indicated with different symbols and the background temperature is from World Ocean Atlas 2018 (Locarnini et al. 2018).

(3) Fostering a vibrant community

We purposefully ran our workshop in hybrid mode to include as many people as possible. Although many parts of society are opening up for in-person activities, many of our colleagues do not feel comfortable traveling for medical reasons, or simply wish to travel less due to caring responsibilities, and to reduce carbon footprints. We saw providing a high-quality hybrid option as an equity issue. To enable our hybrid participation, we had a dedicated virtual poster session with individual Zoom rooms for synchronous participation. Each poster had a virtual wall on Padlet (padlet.com) for asynchronous participation and follow up comments. Each Padlet wall included the abstract and poster, and presenters were encouraged to include a brief video explaining their main points, any relevant manuscripts/preprints and/or any other information. Discussion groups were facilitated in-person or on Zoom (not mixed), while for the final reporting, both virtual and in-person groups came together. Talks were a mix of virtual and in-person, and recorded for storage online for three months post workshop. We also ran a session dedicated to discussing Equality, Diversity, and Inclusion that was facilitated by Prof. Mea Cook (Williams College, USA) and an early-career researcher event.

Acknowledgements

Funds from the European Geoscience Union Galileo Conference and UK-IOPD additionally supported this workshop.

affiliations

contact

Heather Ford: show mail address

REFERENCES

Locarnini et al. (2018). World Ocean Atlas 2018, Volume 1: Temperature. NOAA Atlas NESDIS 81, 52pp

McClymont E et al. (2020) Clim Past 16: 1599-1615