PAGES 2k trans-regional projects originate from 2k Network members and address research questions that involve more than one 2k region. These projects complement the work of the regional groups and take advantage of expertise and data compilations being generated as a result of the global 2k Network. All projects are open for participation by interested scientists. To propose a new trans-regional project, please contact one of the 2k project coordinators.
A first goal of this project was the comparison of the PAGES 2k continental-scale temperature reconstructions with the multi-model simulations of the past millennium, blending the PAGES2K and PMIP3 communities. The comparative analyses emphased climate change at regional scales and an understanding of the mechanisms of climate change at decadal to centennial timescales. Read the outcome "Continental-scale temperature variability in PMIP3 simulations and PAGES 2k regional temperature reconstructions over the past millennium", published in Climate of the Past, here.
Contact: Hugues Goosse (PMIP Liaison & 2k co-coordinator)
This project is devoted to the comparison of the hydroclimate reconstructions with the multi-model simulations of the past millennium, blending the PAGES2K proxy communities and PMIP3 modeling communities. The comparative analyses emphases the methods appropriate for data-model comparisons that target hydroclimate in order to understand climate change at regional scales and the mechanisms of climate variability at decadal to centennial timescales.
Reconstruction Methods Development
The results of Phase 1 of the 2k project have shown that climate reconstruction methods currently face important challenges. Most notably, large uncertainties remain when combining annual with lower-resolution time series, integrating age-uncertain records, and working with data, such as precipitation records, that are subject to significant spatial decorrelation. This project aims at developing methods that incorporate network, observational, and chronological uncertainty into quantitative spatiotemporal estimates of past climate variability, including approaches that allow for quantitative calibration and validation of low-frequency variability.
Contact: Kevin Anchukaitis
Integrating Annual with Decadal Resolutions
Integrating multiresolution records into a composite climate reconstruction is an ongoing challenge. This effort builds on the Pairwise Comparison (PaiCo) approach to climate reconstructions developed recently and the work on incorporating time uncertain records. The method combines proxy evidence derived from annually resolved and lower-resolution records; in contrast to approaches using explicit transfer functions the requirements regarding the calibration of the proxy records can be relaxed.
Contact: Johannes Werner
Global 2k Open-Access Proxy Climate Database
The growing PAGES 2k global database is a publicly accessible, comprehensive database from which researchers can address scientific questions relevant to climate of the last two millennia. It is being used for comparisons with model simulations, for trans-regional climate reconstructions, and to advance climate reconstruction techniques. Regional groups are collecting temperature and precipitation proxy records following a uniform screening strategy, and using a data-entry template that has been created in collaboration with NOAA-Paleoclimatology. Geochronological data are included for time-uncertain proxy records. The temperature and precipitation databases will be publicly released upon acceptance of the related articles. The new temperature dataset (version 2) will also be used to generate a rudimentary global temperature reconstruction, which will be published along with the database (see project “data descriptor”). See more here: www.pages.unibe.ch/workinggroups/2k-network/data
Global 2k Paleotemperatures Dataset v2 - Data Descriptor
The "data descriptor" for version 2 of the 2k paleotemperature database will accompany the publication of the dataset. This new type of peer-reviewed data-oriented publication is designed to promote greater understanding, accessibility and reuse of datasets. The data descriptor will include the selection criteria, and basic diagnostics of the dataset, including a first-pass, index reconstruction of global temperature. This will provide a better global temperature reconstruction than the average of the regional reconstructions, which was published in the 2013 2k Consortium paper. Reconstructions of spatial patterns of temperature variability will be tackled in a subsequent project (see “Global Temperature Reconstruction” project, below).
Contact: Julien Emile-Geay
Water Isotope Database
Stable water isotopes detect regional-scale circulation patterns, making them excellent tracers of the water cycle’s response to climate change. This Trans-Regional Project will create a global database of stable oxygen and hydrogen isotope records that researchers can use to assess regional- and global-scale changes in rainfall and atmospheric/oceanic circulation patterns during the past 2,000 years.
See the goals of this project here.
Global Hydroclimate dataset v1
Once the temperature database is completed (see "Global 2k Paleotemperatures Dataset v2 - Data Descriptor"), hydroclimate records will be added. As for temperature, all records will be collected regionally following uniform selection criteria. The collection of “extreme event” data will also be considered.
Reconstructions based on the PAGES 2k Temperature Database
Global gridded temperature reconstruction method comparisons
This project will produce global gridded temperature reconstructions using a suite of climate field reconstruction (CFR) methods applied to the new PAGES 2k temperature database. The aim is to assess how the results of the various methods agree and disagree (such as low-frequency amplitudes vs. decadal-scale fluctuations, timing of extremes, spectral slopes, spatio-temporal distribution of skill and uncertainties), to better constrain what type of analysis CRF products are best suitable for. If you are interested to contribute please write to the contact address.
Contact: Raphael Neukom
Global 2k annual mean temperature reconstruction using GraphEM
This project focuses on the global mean-annual temperature field using the Graphical Expectation-Maximization (GraphEM) algorithm. The methodology features improved spatial skill, validated uncertainty quantification, and will be used to perform detection & attribution of climate change in PMIP3 past1000 simulations. It will focus on the high-resolution (<5y) records in the new PAGES 2k temperature database.
Contact: Julien Emile-Geay
Global mean temperature (index) reconstruction
This collaborative group effort aims to use the PAGES 2k temperature proxy database to produce reconstructions of global mean surface temperature (GMST) over the past 2000 years.
A range of state-of-the-art reconstruction techniques will be applied in coordinated reconstruction experiments to maximise comparability across the results. The index reconstructions will be used to identify and quantify features of global mean temperature change that stand up to a wide range of reconstruction choices and approaches.
Contact: Raphael Neukom
Multivariate Climate Fields Reconstructions
The next generation of regional PAGES 2k climate reconstructions should target reconstructions of hydroclimate as well as temperature. In some cases, it may be possible to reconstruct specific hydroclimate variables. In many cases, however, it may be impossible to distinguish the combined influences of temperature and precipitation in the proxy records. In these cases we recommend the reconstruction of targets that combine multiple climate influences using both statistical methods based on the records only and simulations with data assimilation, ideally including forward proxy models.
Onset of Industrial Warming in Terrestrial and Marine records
This study compares the newly compiled sea surface temperature records of the Ocean2k group to the regional continental index reconstructions of the 2k Network (See “Regional temperature index reconstructions”, below), to examine how Industrial-era warming developed between the oceans and the continents.
Contact: Nerilie J. Abram
AMOC and atmospheric circulation pattern estimations
Marine paleoclimate data described in the Ocean2K paleodata metadatabase will be combined with CMIP5 simulations to reconstruct ocean circulation patterns using the proxy surrogate reconstruction algorithm. We will also evaluate the precision and uncertainty of the results, and use pseudoproxy experiments to identify regions for which additional data might most improve the results.
Temperature index reconstructions were created for seven continental-scale 2k regions. All regional groups used the set of data and methods deemed most appropriate in their region. In addition, to assess the influence of the various reconstruction methods, all regional reconstructions were also calculated using a common set of methods. This study showed that the most coherent feature in nearly all of the regional temperature reconstructions is a long-term cooling trend. There were no globally synchronous multi-decadal warm or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age. And, that the twentieth century ranked as the warmest or nearly the warmest century in all regions except Antarctica More details to this study here (FAQ).
Contact: Darrell Kaufman
This study used proxy temperature records from the Australasian, South American, African and Antarctic PAGES 2k working groups to create a new Southern Hemisphere temperature reconstruction for the last 1000 years. This reconstruction was then compared to the Northern Hemisphere ensemble temperature reconstruction by Frank et al. (2010) and climate model simulations. The results (Neukom et al. 2014) indicate distinct differences in temperature fluctuations between the two hemispheres over large parts of the last Millennium. Model simulations appear to underestimate these inter-hemispheric differences and the role of internal ocean–atmosphere dynamics, particularly in the ocean-dominated Southern Hemisphere.
Contact: Raphael Neukom
Over more than two years (2011-2013), the regional 2k data managers worked closely with the National Climatic Data Center at NOAA to tailor the 2K Network database infrastructure for paleoclimate data, and prepare the upload of the PAGES 2k database. In addition, they provided expertise and advice that helped promote improvements in NOAA-Paleo’s ingest of paleoscientific data in general. Because the data managers of the regional 2k groups are spread across the globe, the collaboration was organized around bi-monthly teleconference meetings under the lead of NOAA-Paleo. Read more about the 2k-NOAA data managers meetings and their outcome here.
Contact: Eugene Wahl