Abstract. Field-based measurements are foundational to the study of short- and long-term peatland carbon dynamics. For decades, the scientific community has amassed hundreds of valuable empirical datasets in the form of peat core records from around the world. Those records typically include peat depth, basal age, peat organic matter content, peat dry bulk density, peat organic density, and/or carbon and nitrogen content. Once combined with chronological constraints and models, peat core time series can be used to estimate changes in peat-carbon accumulation rates through time. Consolidating these peat records can help improve global peat-carbon stock estimates and quantifications of past, present, and future greenhouse gas exchanges between peatlands and the atmosphere. Large-scale synthesis can also shed light on the sensitivity of peat-carbon accumulation processes to climate change and provide context for current and future global environmental change. We can also use spatial and temporal peat data to inform, validate, and benchmark existing models that include peatland representations. This paper presents the first formal version of PAGES’ C-PEAT Global Peatland Carbon Database (GD), which is available for download in the PANGAEA and International Soil Carbon Network (ISCN) data repositories. The C-PEAT GD contains 267 independently catalogued peat cores and a large number of observations from those cores, including: peat depths, organic matter content values, dry bulk density values, organic density values, as well as carbon and nitrogen content values. Raw and calibrated chronological data are included for each individual dataset when available. The metadata fields are easily searchable and interoperable, as per PANGAEA’s standards. The main objective of this article is to describe the structure and content of the database, itself aimed at increasing the use, assimilation, and interoperability of peat-core data across disciplines. The C-PEAT GD can be accessed at the PANGAEA data repository (https://doi.org/10.1594/PANGAEA.986891; Loisel et al., 2025).

Abstract Peatlands are among Earth’s largest terrestrial carbon stores and are crucial for climate regulation, biodiversity conservation, and water security. Yet peatlands worldwide are deteriorating under pressures from climate change and human disturbance. Strategic, globally coordinated research is urgently needed to protect, restore and manage peatlands so they can continue to deliver essential ecosystem services. To meet this challenge, here we present a global research prioritisation for peatland science, based on a two-stage online survey and expert voting exercise involving 467 participants from 54 countries. We identify 50 priority research questions spanning carbon dynamics, climate impacts, restoration and management, technological innovation, and community and policy engagement. These questions provide a community-informed agenda to guide peatland research over the next decade. Addressing them will help close critical knowledge gaps, strengthen evidence-based decision making, and support the role of peatlands in achieving global climate and biodiversity goals.

High-Andean peatlands (bofedales) are part of a social-ecological system managed and used by pastoralists as forage for their livestock and a water source during the dry season. Maintaining healthy bofedales is important for pastoralist communities as well as critical zone function (watershed management, including water flow regulation and soil carbon sequestration). In our study region, bofedales are found near the headwaters of the Vilcanota-Urubamba River, which eventually flows into the Amazon River, influencing millions of people and ecosystems. The scientific data needed to develop predictive, process-based ecohydrological models of bofedales remain sparse. In contrast, local pastoralists have a narrative of changing environmental conditions effect on those ecosystems and a deep understanding of bofedal functioning. We performed semi-structured interviews in four local communities on the north and south sides of the Cordillera Vilcanota, Peru. Interview results are intended to inform the development of a bofedal ecohydrological model and develop model outputs that may be of use for local communities. The most frequently discussed topics were the effects of drought on bofedal health and associated need for bofedal maintenance through irrigation suggesting human management of critical zone processes. We note that irrigation — despite its omnipresence across the study region — is seldom mentioned in ecohydrological studies of bofedales. Our study begins to address this knowledge gap; we present a landscape-scale bofedal conceptual model that emphasizes hydrological complexity and includes irrigation. By integrating local knowledge into a process-based model, we provide outputs that may be socially meaningful and trusted by local management actors.

Tropical peatlands, compared to their boreal counterparts, are vastly understudied despite acting as a significant terrestrial carbon sink, sequestering 100—300 Gt of carbon. In particular, the low number of field-based studies from Latin America and the Caribbean limits our knowledge of these important wetland ecosystems. Across the tropical Panamerican region, peatland location, soil characteristics, inception ages, and carbon accumulation histories remain largely unknown. These datasets are needed to inform a mechanistic understanding of why peat develops in certain areas but not in others, both in terms of peat initiation conditions as well as the factors that enable peat to subsist over centuries and millennia. Here we present extensive, high-resolution laboratory datasets from 11 peat cores from 4 peatland types from Costa Rica (high-elevation, riverine, coastal palm swamp, and mangrove). A multi-proxy palaeoecological approach was employed to shed light on the successional pathways and past conditions that have allowed these peatlands to form, as well as to provide a first estimate of their carbon stock. The core characterization includes radiocarbon dating, loss-on-ignition, carbon and nitrogen content, and plant macrofossils. Fourier transform infrared spectroscopy (FTIR) was also used to assess changes in organic matter quality across sites and over time. The averaged peatland carbon stock in Costa Rica is estimated at 1080 MgC ha−1, making these ecosystems exceptionally rich carbon stores that are comparable to values found in lowland Amazonian peatlands. Overall, this research provides a basis for understanding long-term carbon accumulation within Caribbean tropical peatlands.

The peatlands in Kalimantan exhibit diverse geomorphological characteristics, but their initiation timing and drivers remain unclear due to limited chronological data. Using 55 radiocarbon ages and Bayesian age‒depth modeling of 15 peat cores, we reconstructed the development and carbon accumulation histories of inland and coastal peatlands in West and East Kalimantan. Coastal peat initiation occurred during the middle Holocene, coinciding with postglacial sea-level high stands, whereas inland peat formation began in the late Pleistocene. Carbon accumulation rates peaked in the middle Holocene (coastal: 63–72 g C m−2 yr−1; inland: 53–89 g C m−2 yr−1) under stable hydrological conditions but declined in the late Holocene (coastal: 49–55 g C m−2 yr−1; inland: 58–63 g C m−2 yr−1). The total decline rate was insignificant, at approximately 0.68 Mt C yr−1. These findings indicate that a sustained water balance is crucial for long-term peat growth and carbon sequestration and that hydrological disruption reduces the carbon storage. The current decline in the carbon sequestration capacity of drained tropical peatlands in Kalimantan is 32.4 Mt C yr−1 (118 Mt CO2-eq yr−1) over a 40-year period, representing approximately 47.5 times the natural decline in carbon sequestration over the past 4000 years.

Observations on the North Slope of Alaska have revealed patches of Sphagnum peat within the widespread matrix of tussock tundra on mineral soils. Little is known about the developmental history of these Sphagnum patches and whether they represent incipient peatlands established in response to warming-related environmental changes. Nine peat cores were collected from nine Sphagnum-dominated peat patches spanning an approximately 300-km longitudinal gradient on the North Slope to determine their development and establishment history. Stratigraphically constrained cluster analysis was applied to plant macrofossil data, carbon-to-nitrogen ratios, and total organic matter measured from bulk peat to delineate developmental phases, and radiocarbon dating was used to constrain the timing of Sphagnum peat patch establishment. We compared these data to changes in testate amoeba community composition and amoeba-inferred water-table depth and pH in six of the peat cores. We also compared Sphagnum peat-patch development and establishment history to paleoclimate and local instrumental temperature records. Results indicated a predictable pattern that describes the transition from moist tussock tundra to Sphagnum peat. Furthermore, although Sphagnum has been present on the North Slope for millennia, our data suggest that Sphagnum-dominated peat patches constitute recent landscape features, mainly established in the 1800s and 1900s, and with rapidly increasing Sphagnum abundance in the past 50 years. Sphagnum expansion was associated with pronounced changes in testate amoeba communities, including an increase in mixotrophic taxa and species associated with densely growing Sphagnum, and community changes consistent with drying and increased acidity. The recent development of Sphagnum-dominated peat patches has been associated with warming air and soil temperatures, active layer deepening, and earlier snowmelt. Sphagnum expansion has also been observed in other arctic regions, and understanding the extent and growth potential of Sphagnum peat patches has implications for understanding and anticipating changes in carbon cycling, edaphic conditions, permafrost thermal regimes, and floristic diversity.

This article presents the first published peatland map for Costa Rica. A probabilistic approach using vegetation, ecosystem, and soil datasets was used to predict the distribution and extent of peatlands found below 700 m in elevation. High-elevation sites found in the Talamanca Mountains were manually identified using satellite imagery; those peatlands are small in size (< 0.05 km2). Our analysis produced an estimated low-elevation peatland extent of 1433 km2 and a high-elevation peatland extent of 23.08 km2, yielding an estimated total extent of 1456 km2 for Costa Rica. This figure falls close to the middle of previously published extent estimates for this country, which vary widely (577-2670 km2). An agreement analysis between previously published maps and this new product is also presented. Plotting the peatland area of Costa Rica in a climate space (mean annual precipitation vs. precipitation seasonality) highlights key climatic differences between our peatland types/regions, hinting at broad-scale effects of climate-landscape interactions. As for the probability map therein, we stress that its accuracy is limited by data availability and quality, as well as ground-referencing information. Still, the new product can provide guidance for land management, policymaking, and future science endeavors.

BACKGROUND:Peatlands are globally-important carbon sinks at risk of degradation from climate change and direct human impacts, including drainage and burning. Peat accumulates when there is a positive mass balance between plant productivity inputs and litter/peat decomposition losses. However, the factors influencing the rate of peat accumulation over time are still poorly understood. METHODOLOGY/PRINCIPAL FINDINGS:We examine apparent peat accumulation rates (aPAR) during the last two millennia from 28 well-dated, intact European peatlands and find a range of between 0.005 and 0.448 cm yr-1 (mean = 0.118 cm yr-1). Our work provides important context for the commonplace assertion that European peatlands accumulate at ~0.1 cm per year. The highest aPAR values are found in the Scandinavian and Baltic regions, in contrast to Britain, Ireland, and Continental Europe. We find that summer temperature is a significant climatic control on aPAR across our European sites. Furthermore, a significant relationship is observed between aPAR and water-table depth (reconstructed from testate-amoeba subfossils), suggesting that higher aPAR levels are often associated with wetter conditions. We also note that the highest values of aPAR are found when the water table is within 5-10 cm of the peatland surface. aPAR is generally low when water table depths are < 0 cm (standing water) or > 25 cm, which may relate to a decrease in plant productivity and increased decomposition losses, respectively. Model fitting indicates that the optimal water table depth (WTD) for maximum aPAR is ~10 cm. CONCLUSIONS/SIGNIFICANCE:Our study suggests that, in some European peatlands, higher summer temperatures may enhance growth rates, but only if a sufficiently high water table is maintained. In addition, our findings corroborate contemporary observational and experimental studies that have suggested an average water-table depth of ~10 cm is optimal to enable rapid peat growth and therefore carbon sequestration in the long term. This has important implications for peatland restoration and rewetting strategies, in global efforts to mitigate climate change.

This study aims to investigate peatland initiation and accumulation across different regions of Kalimantan, Indonesia. The research spans the inland undrained tropical peat forests in the upper Kapuas River, West Kalimantan Province, and Lake Siran in East Kalimantan Province, along with the coastal drained and converted peatlands in the Lower Kapuas River and the Mempawah River in West Kalimantan Province. Peat chronologies were constrained using radiocarbon dating and Bacon age-depth modeling. Inland peatlands in the upper Kapuas River began to form earlier, as early as the Late Pleistocene (~40k BP), while coastal peats in the Lower Kapuas River started much later, during the Holocene (~8k BP). Inundation of depression areas in the upper Kapuas River supported the formation of the Late Pleistocene peats. The apparent carbon accumulation of coastal peatlands appears higher during the early and middle Holocene than in the late Holocene, opposite from the expected autogenic trend. We propose that inundated areas were wet enough to accumulate peat in their soils during the late Pleistocene. However, a cooler climate limited the extent of peat accumulation in the peatlands of the upper Kapuas River. In contrast, during the Holocene, the climate became wetter while experiencing lower precipitation seasonality. Wet climates, together with higher insulation and sea level rise after the LGM, could have produced consistently waterlogged and warm conditions (especially in coastal areas) that facilitated the more rapidly accumulating peatlands of Kalimantan's Eastern and Western coasts. The long-term apparent carbon accumulation rates ranged between 21 and 34 g C m-2 y-1 (0.3-0.5 mm peat accumulation per year) in the Late Pleistocene and 52 and 85 g C m-2 y-1 (0.6-1.7 mm peat accumulation per year) in the Holocene. Accordingly, undrained and anthropogenic disturbance-free tropical peat forests have the potential to act as important carbon sinks.

Anthropogenic carbon dioxide (CO2) emissions are the main driver of climate change, with global warming increasing almost linearly with cumulative CO2 emissions. Hence, future warming will primarily result from future emissions of CO2 with contributions from other greenhouse gases (mostly CH4 and N2O) and aerosols. Climate projections of the 21st century, such as those assessed by the IPCC, are provided from comprehensive climate models, also called Earth System models, driven by scenarios of the 21st century evolution of emissions from those climate forcers. While it seems now inevitable that the world will reach 1.5°C of warming above pre-industrial levels by the early 2030s, the extent to which we exceed this warming level and how quickly we may be able to reduce temperatures again depends strongly on global activity taken now to limit emissions. In this paper, we review the current understanding on Earth system changes under two highly contrasted possible future worlds. We first focus on high-end scenarios, where anthropogenic emissions continue to increase over the course of the 21st century, leading to large warming levels, associated impacts on all components of the Earth System, and increased risks of triggering tipping points. We then assess low-end scenarios, where anthropogenic emissions rapidly decline, reaching net zero and potentially becoming net negative before the end of the 21st century. Such “overshoot” scenarios lead to a peak in global warming followed by a slow decline in global temperature, with some degree of reversibility in the global carbon cycle and key Earth system components. We also review paleoclimatic information relevant to these two contrasting future worlds. Paleoclimate evidence for geo-biosphere interactions shows that stabilizing feedbacks operate on millennial or longer timescales, whereas destabilizing feedbacks and tipping cascades occurred also on shorter timescales.

Stable isotope data have made pivotal contributions to nearly every discipline of the physical and natural sciences. As the generation and application of stable isotope data continues to grow exponentially, so does the need for a unifying data repository to improve accessibility and promote collaborative engagement. This paper provides an overview of the design, development, and implementation of IsoBank (www.isobank.org), a community-driven initiative to create an open-access repository for stable isotope data implemented online in 2021. A central goal of IsoBank is to provide a web-accessible database supporting interdisciplinary stable isotope research and educational opportunities. To achieve this goal, we convened a multi-disciplinary group of over 40 analytical experts, stable isotope researchers, database managers, and web developers to collaboratively design the database. This paper outlines the main features of IsoBank and provides a focused description of the core metadata structure. We present plans for future database and tool development and engagement across the scientific community. These efforts will help facilitate interdisciplinary collaboration among the many users of stable isotopic data while also offering useful data resources and standardization of metadata reporting across eco-geoinformatics landscapes.

In July and August of 2023, we visited Costa Rica to examine some of the country’s peatlands. The purpose of our trip was to collect peat samples from a variety of wetland habitats from the coast to the highlands for future analysis. We summarize our observations in this short essay.

Tropical peatlands are being lost at a rate three times greater than forests, with large and rapid impacts on carbon and water cycling, biodiversity, and human health. Despite threats from land conversion and climate change, peatlands across the tropical biome remain poorly mapped, making it difficult to develop sustainable management solutions. Superimposed on this dearth of spatial data is poor knowledge of peatlands’ net carbon balance. In this Review, we synthesize information on the paleoecology, carbon dynamics, and distribution of the peatlands of the Caribbean. Though data limitations are substantial, this work contributes to further confirm peatland occurrence and further our understanding of their functioning. Caribbean peatlands are a critical ecosystem that remain poorly understood, according to a synthesis of paleoecology, carbon dynamics and mapping data: estimations of distribution and extent vary by more than 200% depending upon mapping technique

Northern peatlands store globally-important amounts of carbon in the form of partly decomposed plant detritus. Drying associated with climate and land-use change may lead to increased fire frequency and severity in peatlands and the rapid loss of carbon to the atmosphere. However, our understanding of the patterns and drivers of peatland burning on an appropriate decadal to millennial timescale relies heavily on individual site-based reconstructions. For the first time, we synthesise peatland macrocharcoal re-cords from across North America, Europe, and Patagonia to reveal regional variation in peatland burning during the Holocene. We used an existing database of proximal sedimentary charcoal to represent regional burning trends in the wider landscape for each region. Long-term trends in peatland burning appear to be largely climate driven, with human activities likely having an increasing influence in the late Holocene. Warmer conditions during the Holocene Thermal Maximum (similar to 9e6 cal. ka BP) were associated with greater peatland burning in North America's Atlantic coast, southern Scandinavia and the Baltics, and Patagonia. Since the Little Ice Age, peatland burning has declined across North America and in some areas of Europe. This decline is mirrored by a decrease in wider landscape burning in some, but not all sub-regions, linked to fire-suppression policies, and landscape fragmentation caused by agricultural expansion. Peatlands demonstrate lower susceptibility to burning than the wider landscape in several instances, probably because of autogenic processes that maintain high levels of near-surface wetness even during drought. Nonetheless, widespread drying and degradation of peatlands, particularly in Europe, has likely increased their vulnerability to burning in recent centuries. Consequently, peatland restoration efforts are important to mitigate the risk of peatland fire under a changing climate. Finally, we make recommendations for future research to improve our understanding of the controls on peatland fires.(c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Peatlands cover only 3% of the land on Earth but store 24% of global soil carbon.Organic carbon decomposition is slow in peatland ecosystems and thus allows peatlands to become stable and significant carbon reservoirs over millennia.However, the relative contribution of carbon preservation mechanisms over millennial timescales (e.g.soil saturation, mineral protection, inherent stability based on molecular structure) within peatlands are poorly understood.This project aims to develop a deeper understanding of how peat stores carbon for long timescales by studying its molecular-level chemical composition.Prior research has suggested that peat retains organohalides that may be resistant to microbial degradation.Samples from multiple peat cores that were collected in southern Patagonia (~ 52°S) were probed for bromine speciation and concentration using X-ray Absorption Near Edge Structure (XANES) spectroscopy.The peat cores are several meters deep and thousands of years old.The XANES data show that organobromine becomes progressively enriched downcore in one of the coastal peat cores, suggesting organobromine may be biogeochemically stable in this location.To shed light on the molecular-level chemical characterization of these samples, we also analyzed a subset of the peat samples using high-resolution mass spectrometry.The peat samples were freeze-dried, homogenized, and extracted with 1:1 v:v methanol:dichloromethane through sonication.A Bray-Curtis dissimilarity test was performed for all chemical features, revealing that the chemodiversity of these samples is driven by age.Specifically, surface, i.e., younger, samples show higher variability in chemical composition, while deeper core samples, i.e., older than 4000 years, showed lower variability.These findings suggest that organic carbon biogeochemical processes, such as humification, may play a role in the convergence of chemical similarity in older samples.Two organohalides were putatively annotated via high-resolution mass spectrometry.Although the bulk organic carbon concentration is stable downcore and through time, variabilities in chemodiversity and increases in brominated organic carbon indicate that underlying reactions continue to transform peat organic matter throughout burial.

The southern westerly winds influence weather patterns and water resources across the southern high-latitude regions, with important socioeconomic impacts. The strengthening and poleward migration of these winds since the late 20th century also have implications for regional environmental change, including drought, wildfire, and sea-ice loss. However, it is challenging to recognize the natural variability of the westerlies and predict their future behavior, as those recent changes have been influenced by anthropogenic factors. We present a 4200-yr-long record from a southern Patagonian peatland in a location that is sensitive to changes in the position and/or strength of the westerlies. Our δ13C record shows a 6‰ increasing trend from 4200 to 1200 cal. yr B.P., indicating a progressive, millennial-scale increase in peatland moisture. This long-term trend is attributed to an increase in moisture induced by strengthening southern westerly winds associated with a change in the mean state of the El Niño–Southern Oscillation (ENSO) system. Superimposed on this millennial trend, centennial-scale shifts in hydroclimate persist into modern times. We suggest that a “paleo”–Southern Annular Mode, which is linked to tropical Pacific climate, with dry events contemporaneous with positive phases and La Niña–like conditions, is responsible for this enhanced hydroclimate variability. Overall, our results point to millennial- and centennial-scale changes in hydroclimate during the late Holocene that link tropical Pacific climate variability with the Southern Annular Mode and the southern westerlies, with far-reaching implications for future changes in the southern high latitudes, including CO2 ventilation from the Southern Ocean.

Peat-core records have a long history of being used for paleoclimate reconstructions in northern high-latitude regions but are less common in the southern tropical zone. In this study, we present a synthesis of published peat-core reconstructions and basal ages from high-elevation (>3000 m a.s.l.) sites in the northern and central Andes of South America. We complement this database by providing a new multi-proxy peat-core-based paleoecological reconstruction from the Alta Murmurani peatland, Cordillera Vilcanota, Peru. This record, with a peat inception age of 8980 cal. yr BP, was analyzed for plant macrofossils and stable isotopes (carbon, oxygen). This review (1) assesses the timing of peat initiation and development across the tropical high-elevation region of South America (8 degrees N to 27 degrees S); (2) assesses the reliability of peat-core paleoclimate reconstructions by comparing the peat-core inferences across sites and against other independent archives (e.g., lake sediments, ice cores, speleothems); and (3) determines which hydroclimatic conditions are favorable for peat formation and expansion across the study area. Our results show that peat initiation occurred throughout the Holocene, progressing from the northern Andes to central Andes, with highest initiation frequencies clustered at ca. 10,700 cal. yr BP and 8300 cal. yr BP, respectively. Our synthesis reveals that peat cores can be used to assess regional paleoclimate trends in the central Andes using a multi-proxy approach combining micro-and macrofossils such as pollen, stable isotopes, as well as organic and inorganic elemental analyses. We also identify three optimal peat-forming time periods, all with optimally wet conditions occurring at transitional hydroclimate phases: (1) following deglaciation, with warming temperatures and increased moisture related to glacial runoff (ca. 11,000 cal. yr BP and similar to 8000 cal. yr BP), (2) under moderate moisture regimes related to intensifying ENSO and warmer conditions (similar to 3500 cal. yr BP), and (3) under conditions related to increased precipitation at the beginning of a cold period (Little Ice Age). We show that either regional climate (e.g., changes in precipitation) or local conditions (e.g., changes in glacial runoff) can promote peat formation across the study region.

Peatlands are efficient carbon sinks due to waterlogged soils causing oxygen depletion and slowing organic matter decomposition, leading to peat accumulation. However, peatlands are also a natural source of methane (CH4), a powerful greenhouse gas, to the atmosphere. Methane production (by methanogens) and oxidation (by methanotrophs) are controlled by water table depth, soil temperature and hydrochemistry. Measuring CH4 emissions is resource demanding. Several measurements method are used, which introduces potential bias for comparisons among studies. Thus, a simple and reliable indicator tool would be desirable for both researchers and managers. Currently, such a tool does not exist. Testate amoebae (TA), an abundant and diverse group of shelled protists occurring in peatlands, are well-established proxies of present water table depth (WTD). As their shells are well preserved in peat, they are commonly used to infer past hydrological changes using predictive mathematical models called transfer functions. As CH4 emissions are also tightly linked to WTD, and although TA are not directly involved in CH4 production or consumption, we hypothesised that CH4 emissions would be significantly correlated to TA community composition and could therefore be inferred from TA communities living in peatland mosses. We tested this hypothesis using compilations of CH4 plot emissions measurements from European and North American bogs and fens, and TA data from moss samples collected from the same plots. Testate amoeba communities were significantly correlated to CH4 fluxes. As our models were based on several independent studies for both flux measurements and TA communities, methodological differences among studies (e.g., CH4 emission measurements, TA taxonomy) may potentially cause bias in the model. Nevertheless, the results are promising, and this proof-of-concept study suggests that past and present peatland CH4 emissions could be inferred from TA shells preserved in peat over centuries and in mosses growing at the surfaces of peatlands.