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PAGES Magazine articles

Publications
Author
Armbrecht L
PAGES Magazine articles
2022
Past Global Changes Magazine

The study of ancient DNA from sediments (sedaDNA) has great potential for paleoclimate research. Using less than a gram of sediment, this new technique allows ecosystem-wide assessments of Antarctic marine biodiversity over hundreds of thousands of years.
 

sedaDNA: A new paleo proxy

Marine sedimentary ancient DNA (sedaDNA) is DNA from dead organisms that have sunk from the ocean to the seafloor and been preserved there. Over time, layers of sedaDNA accumulate, forming a record of "who" has inhabited the ocean in the past. sedaDNA analysis is an interesting new paleo proxy because the genetic traces of organisms that do not fossilize can be detected, too (Capo and Monchamp et al. 2022). This means that sedaDNA allows us to study past marine biodiversity quite comprehensively across different levels of the food web, including bacterio- and phytoplankton, zooplankton, and potentially even fish, uncovering wide-scale community shifts as a response to past climatic change. Such knowledge is important, as it helps us to better predict the future of marine ecosystems with ongoing climate change and find management strategies to conserve them.

Antarctica: An important location for sedaDNA research

Polar deep-ocean environments are particularly suitable locations for sedaDNA research because they feature favorable conditions for sedaDNA preservation. These include constantly low temperatures and oxygen concentrations (~0°C, ~5 mL/L, respectively, noting that these values vary regionally; Bensi et al. 2022; Garcia et al. 2018; Meredith et al. 2008), and the absence of UV radiation (Karentz 1989). Antarctica and the Southern Ocean are remote and isolated, making them natural climate laboratories to study long-term global change (Barnes et al. 2006).

Sampling logistics in remote Antarctica are difficult, and for sediment studies in particular, large research vessels or platforms are required to have the capacity to drill into the deep seafloor, sometimes several thousands of meters below the ocean surface (Fig. 1). The most suitable coring system to acquire sediments for sedaDNA analysis is piston coring, which "punches a hole" into the seafloor (rather than using active drilling) and thus recovers undisturbed sediments (Armbrecht et al. 2019). The reliance on piston coring means that sedaDNA analyses are restricted to relatively soft sediments, usually found in the upper sediment layers. However, this is not necessarily a limitation – the recovery of sediments of up to ~490 m below the seafloor has been achieved using piston coring (Tada et al. 2015), which, in many Southern Ocean regions, can reach sediments of ages that are far beyond the timescales that allow for detection of ancient DNA.

Deep Southern Ocean sediments have relatively low sedimentation rates compared to coastal areas. For example, in >3,000 m water depth in the Scotia Sea, sedimentation rates have been determined at ~10–40 cm per 1,000 years (in the upper ~430 m; Weber et al. 2021). Thus, even relatively shallow coring can provide access to sediments of considerable age, allowing sedaDNA investigations into changes in marine food web structures over multiple glacial–interglacial cycles.

Figure 1: Importance of Antarctica as a study region and its suitability for sedaDNA research. Listed are the key points that favor the preservation of sedaDNA in this environment and facilitate geological timescale sedaDNA recovery.

Consequently, the limitation on how far back in time ancient DNA analyses can be applied to deep ocean sediments remains not a coring capacity question, but rather one of maximum age of sedaDNA preservation. It is expected that ancient DNA can be preserved for up to ~1 million years under the right conditions (although reports exist of non-replicated/authenticated ancient DNA from bacteria reaching several millions of years; Willerslev and Cooper 2005, and references therein). Until recently, the oldest authenticated sedaDNA had been from terrestrial systems (cave sediments) that were ~400,000 years old (Willerslev et al. 2003). In the Arctic environment, eukaryote sedaDNA has been found in up to 140,000-year-old sediments (Pawłowska et al. 2020). In the Antarctic, marine eukaryote sedaDNA has recently been found in ~1 million-year-old sediments in the Scotia Sea (Armbrecht et al. 2022).

Current applications of sedaDNA research in the Antarctic

Contamination-free sampling techniques are starting to be more commonly used on board research vessels, and sedaDNA research is becoming more frequently incorporated into Antarctic science. For example, in 2019, extensive sedaDNA sampling was undertaken during IODP Exp. 382 "Iceberg Alley and Subantarctic Ice and Ocean Dynamics", using some of the most stringent anti-contamination procedures to date (Weber et al. 2021). In addition to clean sampling (via the use of sterilized core-cutting and sampling equipment), the use of non-toxic chemical tracers to determine potential contamination of the core liners (which can occur during the hydraulically driven piston coring process) was benchmarked in the context of sedaDNA research during this expedition (Weber et al. 2021). Previously, this technique had been routinely used by geomicrobiologists when collecting deep biosphere samples for the study of actively living microbial communities, where contamination by modern microbes is of paramount concern (Sylvan et al. 2021).

The sedaDNA analyses of IODP Exp. 382 samples aimed at the detection of different taxonomic marker genes (genes that are variable enough in their sequence so species-specific determination is possible) to identify marine eukaryotes, including the small and large subunit ribosomal RNA genes (SSU, LSU) and the Photosystem II manganese-stabilizing polypeptide gene (psbO, which only occurs in photosynthesizing organisms; Pierella Karlusich et al. 2022). Both fossilizing and non-fossilizing eukaryotes were detected, including diatoms and chlorophytes (back to ~540,000 years), as well as a range of other eukaryote groups (Fig. 2). This shows that research into many groups of organisms over hundreds of thousands of years using sedaDNA analyses is feasible, and especially so in Antarctica and the Southern Ocean.

Outlook for sedaDNA research in Antarctica

The potential of sedaDNA as a paleo proxy is in (1) its ability to complement the fossil record through the detection of ancient DNA from organisms that don't normally fossilize or otherwise allow for reconstructions of the marine food web, and (2) the possibility to study not only biologic composition of various sites ("who was there") but also the activity and function of organisms that lived there in the past ("what were they doing"). In the Antarctic sea-ice environment, such organisms of interest may, for example, include various fragile diatoms that could be useful as sea-ice proxies (e.g. highly branched isoprenoid producing species; Zimmermann et al. 2020) or other primary producers, such as chlorophytes and non-cyst forming/fragile dinoflagellates (De Schepper et al. 2019). Antarctic krill are also highly abundant in sea-ice environments, though they are currently experiencing hardship due to ocean acidification, warming, and overfishing (Flores et al. 2012). sedaDNA analysis makes it possible to track the presence and dynamics of these important Antarctic species over geological timescales.

Figure 2: Overview and proportions of eukaryote groups that can be detected using sedaDNA in the Antarctic region. Approximate proportions (percentage of eukaryote groups out of total eukaryotes) are based on Armbrecht et al. (2022). Figure created with BioRender.com (note that icon selection depended on availability in BioRender and may not necessarily depict Antarctic species).

Despite significant progress in sedaDNA research during recent years, the discipline is still in its infancy, with some baseline research questions needing to be addressed. For example, preservation biases are important to consider when interpreting sedaDNA data, yet little is known about such biases. It has been shown that sedaDNA degradation correlates with organic matter degradation (Armbrecht et al. 2022), but how well the DNA of certain species is preserved compared to that of others, and how far DNA can be transported with deep ocean currents, is currently unknown but would dramatically improve the accuracy of sedaDNA-derived ecosystem reconstructions.

sedaDNA is only preserved in trace amounts in the deep seafloor, and this scarcity makes it difficult to investigate rare species, which might sometimes be the most suitable indicators for specific environmental conditions. To overcome the hurdles of rare sequence detection in marine sedaDNA samples, high sequencing depths (acquiring many millions of reads) per sample is recommended and is becoming more affordable with the availability of today's next generation sequencing platforms. RNA-based hybridization capture techniques that enrich specific (e.g. rare) target sequences (Horn 2012) might further allow for more detailed investigations into higher-trophic-level organisms such as fish.

In summary, recent improvements in sedaDNA acquisition and analysis techniques in combination with sediment samples from locations characterized by ideal sedaDNA preservation conditions, such as those in polar ecosystems, make the application of this new proxy particularly promising for Antarctic paleo research, and open new doors to food-web-wide reconstructions over hundreds of thousands of years in this vulnerable, remote region. The depth and detail of the picture that sedaDNA can give us of past marine life is only just beginning to be explored.

Publications
Author
Kaufman D, Hunter J & McKay N
PAGES Magazine articles
2022
Past Global Changes Magazine

PAGES Data Stewardship project creates a one-stop-shop for PAGES 2k Network data products, while LiPDverse complements with additional analysis-ready datasets.
 

Data compilations generated by PAGES working groups are used in major science-synthesis products that address high-level global-change research topics. These data products are highly curated and extensively analyzed, with outcomes that are applied in a variety of contexts, including model–data comparisons. Such data compilations are valuable as snapshots of the data available at the time they were assembled. They typically include rich metadata for intelligent reuse and thereby can be merged with an ever-growing collection of paleodata. This pool of paleodata is valuable as it can be searched and analyzed with the intent of addressing new scientific research questions that go beyond an individual dataset. This complementary connection between individual data products and the collective aggregate of datasets is exemplified by the new PAGES 2k Network data portal, which gathers major data products from the PAGES 2k Network (pastglobalchanges.org/2k), and the LiPDverse, a data service for datasets built in the PaleoData (LiPD) framework (McKay and Emile-Geay 2016), which includes most PAGES 2k products (Fig. 1).

Figure 1: Complementary connection between the new PAGES 2k Network data portal, which gathers major data products from the PAGES 2k Network, and the LiPDverse, a data service for datasets built in the PaleoData (LiPD) framework, which includes most PAGES 2k products.

PAGES 2k data portal

The new PAGES 2k data portal (pastglobalchanges.org/science/wg/2k-network/database-map) describes each of the major data products and reconstructions that have been generated by the PAGES 2k Network over the past decade. Data products are organized according to their primary paleodata type and, where applicable, by regions. The portal summarizes the origin and purpose of each data product. It describes the data and metadata contents, and provides links for accessing the datasets and their corresponding publications. A mapping tool provides access to individual datasets within each product. This new platform advances PAGES' commitment to advancing FAIR data principles (PAGES Scientific Steering Committee 2018). It also provided an opportunity for its primary creator—PAGES data steward and early-career scientist, Jasmine Hunter (University of Wollongong, Australia)—to advance her coding and data management skills, while expanding her professional network globally.

LiPDverse

PAGES 2k data products are highly complementary with ongoing projects through LinkedEarth (linked.earth), including the LiPDverse (lipdverse.org). Many current and forthcoming PAGES 2k projects have curated their datasets in the metadata-rich and machine-readable LiPD framework. These products are available through the LiPDverse, a website where users can find, view, and download PAGES 2k and other paleodata compilations, or search for a subset of records within compilations. LiPDverse is an entry point to the LiPD "ecosystem" of analysis and visualization tools, including geoChronR, pyleoclim, and the forthcoming abrupt change toolkit in R (actR). Tools are available, and more are in development, for accessing LiPD-formatted data in R and python. These tools interact with datasets from both LiPDverse and from the Neotoma Paleoecology Database (neotomadb.org), with the goal of streamlining data discovery and analysis, and increasing reproducibility. A recent example based on West Africa paleoclimate records highlights how data from different sources can be assembled, analyzed, and visualized (McKay et al. 2022; earthcube2022.github.io/ec22_mckay_etal). Online tutorials are available to explain how LiPD tools can be applied to PAGES 2k data products, including Arctic2k (nickmckay.github.io/GeoChronR/articles/PCA.html) and Iso2k (nickmckay.github.io/GeoChronR/articles/tidyIso2k.html).

PAGES Data Stewardship Scholarship

The PAGES 2k Network was among the inaugural group of 11 Data Stewardship Scholarships awarded in 2021 (Kaufman 2022). The PAGES 2k data portal is an outcome of the project. PAGES Data Stewardship Scholarships recognize and reward PAGES working groups for their valued efforts to compile and curate data products for the long-term benefit of the global paleoscience community. Any member of a PAGES working group can apply for a Data Stewardship Scholarship; contact your working group leaders. For more information, see the PAGES website: pastglobalchanges.org/science/wg/data-stewardship-scholarship

Publications
Author
Gil-Romera G, Giesecke T & Kuneš P
PAGES Magazine articles
2022
Past Global Changes Magazine

Prague, Czech Republic, 1-3 June 2022

New scientific discoveries are usually achieved based on accumulated knowledge. We are "standing on the shoulders of giants", which is especially true when it comes to the utilization of vast knowledge held in public data repositories (Nieto-Lugilde et al. 2021). These open-access, often community-based data collections are critical to answer complex questions in any scientific domain. This is particularly important in the case of paleoscience, where continental-scale data collections allow us to study environmental changes in four dimensions. Comparing trends of change across several sites permits the separation of local site-specific changes from regional or continental patterns driven by climate and humans.

The European Pollen Database (EPD; europeanpollendatabase.net) has been one of the major public pollen data repositories for more than 30 years, adhering to the FAIR principles (Findability, Accessibility, Interoperability, and Reusability of digital assets) even before they were widely adopted (Wilkinson et al. 2016). The EPD serves as a tool to answer paleoecological (Giesecke et al. 2019), paleoclimate (Davis et al. 2003), and nature–human related research (Fyfe et al. 2015). The database is developed and curated by a volunteer group of data stewards led by Michelle Leydet. Currently, the EPD contains 2456 sites, including 5071 datasets integrating the Alpine Pollen and Archaeological Database (ALPADABA) (Fig 1). To provide timely data access and visualizations, the EDP community decided to join Neotoma (neotomadb.org) as a constituent database, thus contributing to Neotoma's development. Currently, all public data from the EPD are available via Neotoma.

Figure 1: Current sites (2456) in the European Pollen Database (June 2022). Green dots belong to the ALPADABA database (56 sites). All sites have been successfully uploaded to Neotoma. Source: Neotoma explorer: apps.neotomadb.org/explorer

While the number of datasets in the EPD increases steadily, there are regions for which published data are less available. The PAGES-supported in-person EPD Open Science Meeting (pastglobalchanges.org/calendar/128846; epdweblog.org/news-blog)gave another stimulus to scientists to submit their data to the EPD. The migration of the EPD to Neotoma opens new opportunities for storing other paleoecological proxy data, and for that reason the meeting aimed to attract other proxy communities to showcase Neotoma and start discussions. Therefore, topics of keynote talks were chosen to highlight some proxies that are well connected to pollen data: charcoal (E. Dietze), sedimentary ancient DNA (I. G. Alsos and U. Herzschuh), testae amoeba (K. Marcisz), biomarkers (C. De Jonge), vertebrate fauna (D. Schreve), and plant macroremains (L. Amon). T. Giesecke provided an introduction with insights on the history of pollen databases and the EPD, and J. Williams gave an overview of Neotoma. H. Seppä gave a talk on the application of the modern pollen dataset in climate reconstructions, and O. Mottl presented new tools and a workflow to analyze continental-scale pollen data held in Neotoma for specific research questions. The program was completed with two keynotes showcasing exciting local research programs, combining pollen data with information from archaeology (J. Kolář) and the use of herbaria collections to study recent continental-scale spread of neophytes (P. Mráz).

The EPD community sees the need to transfer the knowledge and skill required using the data in standard and sophisticated analyses in order to close the perceived gap between data producers and data users. To this end, attendees had the opportunity to participate in two training workshops out of seven different options: the use of non-pollen palynomorphs in multi-proxy studies (L. Shumilovskikh); how to produce quantitative land-cover reconstructions (M. Theuerkauf and V. Abraham); chronology building using classical and Bayesian statistics (P. Kuneš and G. Gil-Romera); the use of the Neotoma R package (S. Dominguez); inferring fire properties from charcoal timeseries using R (W. Finsinger); pollen-based climate reconstructions in R (B. Davis); and using Tilia to create pollen diagrams and to upload data to Neotoma (M. Leydet, G. Gil-Romera, and I. De Wolf). Participants highlighted the importance of these educational efforts during the workshops, judging them to have a strong impact on their future research and scientific development. In addition, this was the first face-to-face meeting after the COVID-19 pandemic for many attendees, becoming one of the very few occasions that early-career researchers may have to establish stronger networks with their peers early in their careers.

The EPD 2022 meeting was a success in terms of participation (112 people) and inclusivity: more than half were female (70%), with a high proportion of female keynote speakers. There was an impressive representation of early-career researchers (72%) and geographical locations (23 countries).

Publications
Author
Cornacchia I, Boschi C, Braico P, Cristofanelli P, Iadanza A, Montagna P, Regattieri E & Tesi T
PAGES Magazine articles
2022
Past Global Changes Magazine

Pisa, Italy, 22-24 June 2022

Climate change and the global carbon cycle have been influencing each other for millions of years. Yet, understanding and predicting the interactions between Earth's climate and carbon dynamics is challenging due to poorly constrained feedbacks and processes. Today, anthropogenic carbon dioxide emissions into the atmosphere–ocean system are altering the climate at unprecedented rates, making the understanding of carbon and climate dynamics one of the most crucial challenges for our society. To face this fundamental challenge, a new interdisciplinary approach is needed to embrace different geological, biological, and anthropic components with the overarching goal to produce a novel, global scientific view of the Earth system across timescales.

With this goal in mind, the working groups "Paleoclimate Dynamics" and "Carbon Cycle" of the Italian National Research Council (CNR) organized an international workshop "Climate Change and Carbon Cycle: Global change from the deep past to the Anthropocene". Over 70 people (most of them early-career scientists) from 10 countries attended. The workshop consisted of three sessions: Processes, Impacts, and Frontiers. The first session aimed to provide a better understanding on how fast and slow feedbacks in the carbon cycle operate to modulate the evolution of climate and its sensitivity to forcing through time, exploring triggers and tipping points. In this framework, the keynote speaker Prof. Marie Edmonds (Department of Earth Sciences, University of Cambridge, UK) presented the slow geological processes, mostly related to volcanism, that have exerted first-order control on the atmosphere and oceans over geologic timescales.

Figure 1: Sketch showing the different sources of information for studying the global carbon cycle and its relationship with climate across different timescales; keywords are also listed.

The second session tackled the effects of climate changes and carbon-cycle perturbations on the different components of the Earth system over different time intervals, and with a multidisciplinary approach. In this session, the keynote speaker Dr. Richard Sanders (ICOS Ocean Thematic Centre, Norwegian Research Centre, Norway) discussed the consequences of the increasing CO2 concentration in the oceans, highlighting the importance of biogenic carbon, partly overlooked, when estimating the oceanic carbon budget and its rapid changes due to anthropogenic activities. Lastly, the third session focused on the analytical and conceptual boundaries in carbon-cycle–climate system research, to identify common/trans-scale knowledge gaps, and to stimulate discussion on how a combined effort is beneficial for both communities focusing on paleo and modern processes, to overcome current research limitations. The session was closed by keynote speaker Prof. Bärbel Hönisch (Department of Earth and Environmental Sciences, Columbia University, USA); her talk highlighted the importance of CO2 reconstructions over the past 60 million years to tackle the complex relations between this greenhouse gas and global temperature trends in the deep past.

During the workshop, participants traveled through space and time, from the Triassic–Jurassic mass extinction (~201 Myr BP) to the consequences of the 2020 lockdown on the riverine carbon cycle in Tuscan watersheds. Contributions covered research topics at different latitudes, from the Arctic to the Antarctic, and different climates, from the Alpine Critical Zone to the Mediterranean Sea, as well as urban environments. In addition, participants had the chance to visit five different laboratories with the goal of familiarizing themselves with new concepts and methodologies outside their scientific background. The research topics of these laboratories included forest modeling, IODP drilling initiatives, soil geochemistry, terrestrial ecosystem monitoring, marine carbon cycle, and carbonate rocks.

The overall inclusive approach of this workshop succeeded in gathering scientists working on topics of common interest despite the different research tools and timescales of interest. Collectively, the 2022 meeting in Pisa emphasized the need to forge a novel scientific community—multidisciplinary and transdisciplinary—well interconnected and open to new synergies among disciplines.

Publications
Author
Da Silva A-C, Fagel N, Gutiérrez D, Yasuhara M and Grégoire M
PAGES Magazine articles
2022
Past Global Changes Magazine

53rd International Colloquium on Ocean Dynamics & 3rd GO2NE Oxygen Conference, Liège, Belgium, 16-20 May 2022

This colloquium on ocean deoxygenation was organized by the IOC-UNESCO Global Ocean Oxygen Network (GO2NE) and was a contribution to the Global Ocean Oxygen Decade (GOOD) program of the UN Ocean Decade. The meeting involved 183 people onsite and 80 online participants.

During the colloquium, a session on "Ocean Deoxygenation - how the past can inform the future?" was convened by Moriaki Yasuhara, Dimitri Gutiérrez, Anne-Christine Da Silva, and Nathalie Fagel. The session started with Babette Hoogakker's keynote, which reviewed ongoing research on paleodeoxygenation, combining foraminifera geochemistry and climate model simulations, across key warm geological time intervals such as the Miocene and mid-Pliocene. In addition, the session involved 12 talks and 10 posters covering different approaches for reconstructing and interpreting past oxygenation conditions, their drivers, and their impacts on ocean life.

This approach was complemented by proxy development and calibration studies, as well as paleoclimate modeling of changes in ocean oxygenation. For example, past ocean anoxic events leading to mass extinctions that occurred during the Silurian and the late Devonian periods were studied in relation to their orbital forcing by Michiel Arts and co-authors (University of Liège, Belgium). Tim De Backer (University of Ghent, Belgium) then presented evidence of zooplankton malformations associated with increased levels of redox-sensitive metals at the onset of the Lau extinction event in the upper Silurian. Moriaki Yasuhara's talk (University of Hong Kong, Hong Kong) presented deoxygenation and warming impacts on shallow marine communities during the Paleocene–Eocene Thermal Maximum. He showed that habitat compression via oxygen minimum zone expansion occurred in this warmer-than-present condition. Rick Hennekam (NIOZ Institute, The Netherlands) revealed early warning signals of regime shifts associated with anoxic events (sapropels) in sediment records for the past 250 kyr in the Mediterranean Sea.

New insights for the use and interpretation of paleo-oxygenation proxies were presented, involving sedimentary redox-sensitive metals Uranium and Molybdenum by Mareike Paul (University of Helsinki, Finland) and Niels van Helmond (Utrecht University, The Netherlands), as well as trace metal enrichments (Mn/Ca) in the calcareous tests of foraminifera by Inda Brinkmann (University of Lund, Sweden). Notably, first results of tests of cold-water corals as recorders of intermediate water paleoredox state, through the evaluation of Cr and Cr isotope ratios, were discussed by Lelia Matos (CCMAR, Portugal).

Figure 1: Chanxhe Record, Belgium: Alternation of limestones and shales paced by orbital forcing, and at the top of the record, close to the Devonian-Carboniferous boundary (~360 Myr BP), the Hangenberg event is a widespread anoxic event associated with dark shales and mass extinction; dark shales on the left side of the image.

Paleo reconstructions of changes in oxygen minimum zones (OMZs), and associated biogeochemical cycles, involving multiple proxies, were also presented. Catherine Davis (North Carolina State University, USA) used carbon and oxygen stable isotopes, trace metal concentrations, and morphological features of deep-dwelling planktic foraminifera to characterize the deglacial expansion of the Eastern Equatorial Pacific OMZ, and changes of mid-water oxygenation from the Last Glacial to the Holocene.

For reconstruction and understanding of coastal deoxygenation and eutrophication, Dimitri Gutiérrez (Insituto del Mar del Peru, Peru) presented a multi-proxy study, including dinocysts, geochemical proxies, and benthic foraminifera, to track cultural eutrophication in an upwelling-shadow bay of the Peruvian coast. By using state-of-the-art techniques, Constance Choquel (University of Lund, Sweden) used morphological variations of benthic foraminifera to characterize changes of oxygenation in the Baltic Sea over the past 200 years. Johannes Pein (Helmholtz-Zentrum Hereon, Germany) discussed modeling results to analyze the interplay between stratification and sedimentation driving oxygen depletion in coastal environments, with promising implications for management.

Finally, a paleoclimate modeling study by Vyacheslav Khon (Heriot-Watt University, UK) showed exciting results related to the drivers of the deep-ocean deoxygenation in the Last Glacial Maximum, highlighting the impacts of the Pliocene Panama Seaway closure on ocean circulation, net primary production and ventilation that have ultimately contributed to the development of the Eastern Pacific OMZ. Taken together, these studies emphasize the importance of the paleo approach to better understand past, present, and future ecosystems, biodiversity, and climatic impacts on them.

Publications
Author
Moseley GE
PAGES Magazine articles
2022
Past Global Changes Magazine

Innsbruck, Austria, and online, 17-21 July 2022

Karst environments host a rich array of geological archives that allow us to improve our understanding of climatic and environmental changes, as well as landscape and human evolution. Such archives are commonly found in caves where they are both well connected, but also well protected from the surface, with the importance of clastic and chemical sediments being discussed at symposia for over 60 years (Dell'Oca 1961). Since 1996 in Bergen, Norway (Lauritzen 1996), Climate Change: The Karst Record (KR) has been the premier conference for international scientists to present and discuss the latest in cave and karst-based paleoclimate and paleoenvironmental research. Due to the major advances and developments in speleothem science over the last few decades (Henderson 2006), the conference naturally began focussing on speleothem-based research. For the recent KR9 conference (pastglobalchanges.org/calendar/26918), which was held at the University of Innsbruck, Austria, and online, the conference widened its focus. In addition to being a showcase for the latest speleothem research, the meeting also welcomed contributions from those working in the quickly developing (but disappearing) field of cave ice (Fig. 1), as well as the more traditional field of clastic sediments and speleogenetics.

Over three days, 183 delegates (including 34 online) from 30 countries presented 169 oral and poster presentations. PAGES provided funding for 15 delegates, including 11 early-career scientists and five researchers from developing countries. Climate variability on orbital, millennial, decadal, and seasonal timescales was a strong focus of the conference and included keynotes that examined opposite ends of the timescale spectrum. Heather Stoll (ETH Zürich, Switzerland) presented on North Atlantic meltwater pulses and temperature changes in the orbital session, whereas Ashish Sinha (California State University Dominguez Hills, USA) presented in the decadal session on the speleothem record of climate–society relationships in the Indian subcontinent. The integration of speleothem data in climate models and data–model comparisons was also discussed and explored further in a keynote by David McGee (MIT, USA), while Robyn Pickering's keynote on uranium–lead dating of speleothems from the Cradle of Humankind, South Africa, topped off the session on cave records of human history.

Figure 1: The distinctive "ice wall" in Eisriesenwelt (Photo credit: Robbie Shone).

The majority of these presentations were focused on speleothem studies. Thus, an extensive review of cave monitoring, method and technical developments, and geochemical modeling and laboratory experiments, which aimed to improve understanding and analysis of the speleothem archive, were very welcome. A keynote by Hagit Affek (Hebrew University of Jerusalem, Israel) provided valuable insights into the continually developing speleothem 17Oexcess proxy. Beyond the speleothem topics, participants enjoyed presentations on the cave-ice archive, clastic sediments, and a diverse open session. Several presentations were also given online, including poster presentations, and, on the whole, the hybrid format generally worked as well as could be expected. Dakalo Maphanda (University of Witwatersrand, South Africa), Charlotte Honiat (University of Innsbruck, Austria), Melina Wertnik (ETH Zürich, Switzerland), and Marit Holten Løland (University of Bergen, Norway) all received outstanding student presentation awards.

Beyond the main plenary, participants had the possibility to participate in workshops where they developed knowledge and skills in using the Speleothem Isotopes Synthesis and AnaLysis (SISAL; pastglobalchanges.org/sisal) database, speleothem petrography and microstratigraphy, age modeling, and radiocarbon as both a geochronological tool and environmental tracer. Field trips were offered to Spannagel Cave (Spötl et al. 2002), the Hintertux glacier cave, and Eisriesenwelt, the largest ice cave in the world (Fig. 1).

As five years had passed since the last Karst Record meeting in Texas, USA, KR9 provided a much-needed and welcome opportunity for this small but rapidly developing community to meet and discuss developments in the field. In addition, a "mini summer school of speleothem science" took place for early-career researchers in the two days prior to KR9, providing valuable professional development opportunities. Free childcare was offered during the main conference, and KR9 was classified as a Green Event by the local authorities.

The competition to host KR10 was a close one! We look forward to KR10 in South Africa in 2025.

Publications
Author
Burstyn Y, Bühler J, Kaushal N, Rehfeld K, Braun K, Lechleitner F & Goldsmith Y
PAGES Magazine articles
2022
Past Global Changes Magazine

5th SISAL workshop, Jerusalem, Israel, and online, 28 February – 3 March 2022

Accurate model projections of future regional hydroclimate require validation against paleoclimate records. Speleothems, with their strong age control and multiple proxies, are a promising archive for this purpose (Bühler et al. 2021). During Phase 1 of the Speleothem Isotope Synthesis and Analysis working group (SISAL; pastglobalchanges.org/sisal), members of the group published a database containing nearly 700 speleothem isotope records, 500 of which have standardized age models (Comas-Bru et al. 2019). Data–model comparisons utilizing the database have yielded promising results, while stressing that more information from cave monitoring and additional proxies are needed to constrain the interpretation of isotope records, and to provide independent paleoenvironmental information. To address these gaps, the working group aims to expand the database with trace elements and monitoring records during Phase 2 (2020–2023).

This first workshop of Phase 2 was designed to:

  • assess the spatial and temporal distribution of trace element data;
  • formulate targeted research questions;
  • discuss best practices for measurements, data standardization, reduction, and uncertainty estimates; and
  • design the first steps for plans to augment the SISAL Phase 2 database with process-based modeling of the climate–karst–cave system.

The Jerusalem workshop was fully hybrid, with "handshake" sessions organized to connect working groups from the Asian, Australian, and American time zones with the Eastern Mediterranean and European time zones. Fourteen participants, including two senior researchers, and 12 early-career researchers (ECRs, including Master students, PhDs and postdocs) from 10 countries attended the workshop in person. About 10 additional participants joined online.

Figure 1: Sites with monitoring data (SISALv2 and cavemonitoringgroup.wordpress.com) and entities from the SISALv2 database with trace element data superimposed in all SISALv2 entities (blue). The map is modified from The World Karst Aquifer Map (Goldscheider et al. 2020).

On day 1 of the workshop, SISAL members joined the hosting researchers from the Institute of Earth Sciences at the Hebrew University of Jerusalem for a departmental symposium. The symposium hosted 21 speakers (eight talks and 13 short "elevator pitches"). Six senior scientists in the field of karst and climate research presented their research alongside 14 ECRs. In-person audience attendance averaged around 40, and over 60 participants joined online throughout the day.

On day 2, Dr. Nikita Kaushal presented an update of the SISAL Phase 2 work to date on monitoring, trace elements, and long-term data stewardship. This included the datasets identified by the regional coordinators (Fig. 1), database structure, data and metadata fields, quality control, and proposed timelines. Dr. István Hatvani presented the new graphical user interface (GUI) to increase accessibility to the existing SISAL database. The group then brainstormed potential research questions and assigned teams to explore each question. The emerging main research questions included potential proxy system models to bridge the gap between rainwater and speleothem isotopes, and how to find robust regional hydroclimate proxy mechanisms targeting the divalent trace element replacing calcium in speleothem carbonate. Given the time-intensive nature of input to the monitoring database, it was decided that the data input would be targeted and project-specific.

On day 3, the group put most effort into data input and quality control, creating a wish list for metadata, and listing potential datasets for upload. Finally, on day 4, the last work day, the participants were introduced to the karst hydrology model designed by Kübra Özdemir Çalli and Prof. Andreas Hartmann. For the remainder of the workshop, participants circulated between breakout sessions focused on the main research questions from day 2.

On the last day, participants enjoyed a geological field trip to the Soreq Cave, led by Drs. Miryam Bar-Matthews and Avner Ayalon from the Geological Survey of Israel. Later, Prof. Mordechai Stein guided the group to the Dead Sea rift, valley, and lake.

With the workshop concluded, the SISAL working group now has focused research questions that will guide the data collection. Research group leaders were assigned, and a timeline for achieving the goals of the working group was established. SISAL Phase 2 coordinators welcome new volunteers to help in data curation and join the different projects planned for the upcoming months; if interested, please contact SISAL at sisal.sc2@gmail.com.

Publications
Author
Bouimetarhan I & Cheddadi R
PAGES Magazine articles
2022
Past Global Changes Magazine

Session OSM19 at the PAGES 6th Open Science Meeting, online, 16 May 2022

About two-thirds of Africa is arid or semi-arid, and water availability is a critical factor for the wellbeing of ecosystems and anthropogenic activities. Studies of regional hydrologic fluctuations in Africa since the Last Glacial Maximum (LGM) reveal profound implications and impacts on ecosystems and human societies. Reconstructions of paleoenvironmental changes in such critical environments are often hindered by the lack of suitable archives under arid conditions. The 6th Open Science Meeting (OSM) session OSM19, "Understanding past hydrological changes in Africa since the Last Glacial Maximum", was proposed in an attempt to build African research synergies, and provide an overview of the recent research on past climate change since the LGM from different regions in Africa. In this context, the session aimed to provide a better understanding of the spatio-temporal variability of hydrologic changes over Africa since the LGM. This session was dedicated to identifying new hydrological records from Africa, including terrestrial and marine records, with a time span that covered the last 20 millennia. Although the conference was completely online, the session successfully attracted diverse contributions that provided an overview of the ongoing science inland and offshore of the African continent. This session provided a scientific platform to share new records from different areas and time periods based on very interesting proxy records and model simulations to identify long-term climate variabilities, explore mechanisms and dynamics underlying the observed climate changes, and address the impact that hydrological change has had on the evolution of ecosystems and human activities. The session was attended by more than 90 participants, with eight oral contributions and eight posters that presented and discussed the state-of-the-art research of the African hydrological changes since the LGM.

Figure 1: Ecosystem–climate–human interaction in Lake Afourgah (Middle Atlas at 1420 m above sea level, Morocco).

The session was built around three key research foci: (1) paleohydrological and paleoenvironmental changes during the LGM, (2) anthropogenic vs climate effects on African environments during the LGM, and (3) data–model synthesis of spatiotemporal variations in African hydroclimate since the LGM. Panelists (over 60% were early-career researchers) presented their latest research from different parts of Africa and provided a few recommendations. This session highlighted the increasing need of new data for both past climate reconstructions and model simulations/improvement in order to fill existing gaps and obtain a more complete overview of the LGM African hydroclimate. This task can only be fulfilled in a collaborative framework between the marine and terrestrial research communities, and between data and modeling communities. We therefore all agreed to put further efforts into: (1) comparing and integrating, simultaneously and independently, terrestrial and marine records in paleoclimate interpretations; (2) investigating tropical influence on hydroclimate variation in the hyper-arid central Sahara; (3) generating more Late Quaternary Aeolian-fluvial paleoenvironmental archives in Africa; (4) reconstructing high-resolution hydroclimatic and vegetation changes using historical archives and multi-proxy sediment records and (5) providing data–model synthesis of hydroclimatic proxies over Africa. Possibilities are presently being explored to collaborate on these research foci.

The session conveners were satisfied with the quality and the diversity of oral and poster presentations, as well as with the gender balance and the geographical representation. However, we strongly felt that the session was dominated mainly by research from North Africa and the central and eastern Sahara desert. Additionally, the session conveners would like to emphasize that although African climate mechanisms and impacts on regional and local ecosystems can be partially studied by the international community, an increased international scientific effort toward involving institutional cooperation with locally based African scientists, especially West and East Africa, is necessary to make significant progress in this field.

Publications
Author
Evans MN, Valero Garcés B, van Rensburg C, Ait Brahim Y, Schafstall NB, Falster GM & Meissner KJ
PAGES Magazine articles
2022
Past Global Changes Magazine

Roundtable at the PAGES 6th Open Science Meeting, online, 16 May 2022

PAGES recognizes the need to consider concerns about inclusivity and diversity in all aspects of its activities. In advance of the PAGES Open Science Meeting (OSM), and reflecting desires expressed by the PAGES community, an Inclusivity Committee was formed (pages-osm.org/index.php/general-information/diversity-and-inclusion). The inclusivity and diversity roundtable was integrated into the virtual meeting plan of the OSM. Held on 16 May 2022, it was attended by over 90 people from 26 countries.

The roundtable and its outcomes

Discussion of the following questions at the roundtable produced a number of ideas for consideration:

  • How can PAGES obtain more information about diversity and equity concerns? The recommendation was to create a PAGES email address, monitored by a standing committee, to which the community could report problems.
  • Have you ever felt excluded from a PAGES sponsored event, and if so, how? No one present for the roundtable volunteered an example, but we imagine there might be reports if an anonymous survey were to be taken of the entire PAGES community.
  • What are some examples of ways in which PAGES has improved the inclusion of members of underrepresented geographical areas, sociodemographic groups, or in any other ways in its activities and leadership? The discussion noted that PAGES hosts open webinars and requires consideration of career stage and geographic representation at workshops, but could do more.
  • How could PAGES be more inclusive? PAGES could expand its definition of representation and diversity into sociodemographic considerations; encourage hybrid activities that consider time zones, internet connectivity, and systemic barriers to participation by underrepresented groups; create virtual platforms and networking to train a more diverse community in data analysis, a core activity; and give agency to researchers working in underrepresented regions. The PAGES Early-Career Network (pastglobalchanges.org/ecn) provides excellent examples of all these initiatives.
  • What activities and initiatives might a standing PAGES Inclusivity and Diversity Committee pursue? Participants suggested that such a committee would need clear goals and planned outcomes, and to provide regular updates to the community for discussion. New initiatives could include a mentoring program to build capacity in students and early-career researchers, increasing diversity in PAGES' management, SSC, and working group leadership, and publishing a code of conduct or community charter spanning all PAGES activities.

Figure 1: PAGES OSM attendance over time and by location since 2009. Meeting participation roughly reflects PAGES membership distribution and, notwithstanding the COVID-19 pandemic, the growing popularity of the OSMs. Participation data is somewhat skewed by location toward participants from nearby, but otherwise tends to include relatively large proportions of affiliations from Europe and North America.

The path forward

The PAGES International Project Office (IPO) and Scientific Steering Committee (SSC) are actively discussing how diversity and inclusivity might be improved by governance and operational changes. PAGES does not tolerate discrimination or harassment at workshops or meetings and is committed to an open and welcoming environment. But to achieve these goals, we must make education, training, and dialog accessible across the PAGES community. Because PAGES is globally dispersed, we might be best served by self-paced programs. Excellent resources, including the URGEoscience (2020) anti-racism (urgeoscience.org/curriculum) and Safe Zone (2022) LGBTQ+ (thesafezoneproject.com/curriculum) curricula, are available. Finally, we need to set specific goals and regularly assess outcomes. A standing committee or an annual SSC agenda item might meet this need. Everyone gains from progress toward a more just, diverse, and inclusive intellectual community (Willenbring 2020), itself the root of a more creative and dynamic marketplace of ideas (McGee 2021).

Publications
Author
Bouimetarhan I, Cheddadi R, Reddad H, Baqloul A, Carré M, Abouhilal A & the local organizing committee
PAGES Magazine articles
2022
Past Global Changes Magazine

PAGES 6th Open Science Meeting, online, 16-20 May 2022

What would have been an in-person conference in May 2021 in Agadir, Morocco—with on-site sessions, and informal talks during the coffee breaks or at the Agadir bay—turned into an online meeting, postponed due to the world pandemic and uncertainties related to travel restrictions, marking a first in the history of the PAGES Open Science Meetings (OSM; pages-osm.org). Although completely online, we were proud to bring the global paleo community together: 505 participants from 46 different countries attended the 6th OSM online. Among the participants, 40% identified as female; 67% of the attendees were senior researchers; and 33% were students. While 83% of our delegates came from high-income countries, only 17% were from low- and middle-income countries.

The program of this virtual OSM was built around PAGES' scientific themes of climate, environment, and humans, and featured 430 abstracts presented in 31 sessions as 129 posters, 128 lightning talks, and 301 oral presentations, with four parallel sessions running simultaneously. The program included the first PAGES OSM session dedicated to art and science: "Art and science in a changing planet: A past global perspective." Nine keynote speakers provided state-of-the-art contributions on a wide range of paleoscientific topics encompassing glacial refugia and future microrefugia evolution (Rachid Cheddadi, France), the origin of Homo sapiens (Jean-Jaque Hublin, Germany), high and low latitude climate interactions (Hai Cheng, China), learning from past tipping points to avoid future ones (Tim Lenton, UK), the role of paleoclimate model–data comparisons in assessing climate projection levels of confidence (Pascale Braconnot, France), savanna fire response to paleo-rainfall shifts (Alison Karp, USA), flood history of the Himalaya (Pradeep Srivastava, India), dendrochronology and climate in the tropical Andes and lower lands (María Eugenia Ferrero, Argentina), and a past–present–future perspective on using paleoecology to conserve African ecosystems (Lindsey Gillson, South Africa).

Four town halls were organized during the OSM, and were well attended. These included an inclusivity roundtable, a PAGES–Ocean KAN meeting, a workshop on archiving data in community repositories, and a town hall run by the PAGES 2k Network. Despite the fact that the online meeting format did not promote as much social interaction between the participants as it would have in Agadir, the local organizing committee organized a virtual conference dinner where a Moroccan chef guided attendees through some local dishes in a two-hour cook-along session. This session was attended by 30 food lovers from 13 countries.

Figure 1: Word cloud based on the scientific sessions of the 6th Open Science Meeting (Image credit: Lindsey Gillson).

Given the virtual global attendance and the organizational time zone hurdles, all oral contributions were live broadcasts and recorded. The recordings were then made available on the virtual platform to all attendees during the conference and until one month after its end. Currently, all plenaries and opening and closing ceremonies are accessible via the PAGES YouTube channel: youtube.com/PastGlobalChanges/playlists

This online meeting aroused the interest of the local press, with at least six articles in both Arabic and French (mapbenimellal.ma/fr/beni-mellal-ouverture-des-travaux-de-la-conference-internationale-pages-sur-les-changements-climatiques).

The 6th OSM would not have been possible without the strong and sustained commitment of all members of the organizing and scientific committees over almost two years, as well as the great help of the Shocklogic team for managing the online event. We have learned so much about the latest global change research and seen how paleoscientists are undertaking enormous efforts to assess the high complexity of past global changes to gain a better understanding of the general forces controlling them. We thank all participants for their valuable contributions and for taking part actively in the discussions during the conference to make it a successful event, and we hope to see you in person at the PAGES 7th OSM!