Iso2k: A community-driven effort to develop a global database of paleo-water isotopes covering the past two millennia

Abstract:

Iso2k is a new, community-based effort within the Past Global Changes 2k (PAGES2k) project to investigate decadal to centennial-scale variability in hydroclimate over the past 2,000 years. This PAGES2K Trans-Regional Project will create a global database, available for public use, of archives that record the stable isotopic composition of water (δ¹⁸O and δD). Stable water isotopes detect regional-scale circulation patterns, making them excellent tracers of the water cycle’s response to changes in climate. Researchers will use the database to identify regional- and global-scale features in hydroclimate and atmospheric circulation during the past 2kyr and their relationship with temperature reconstructions. Other key science questions to be addressed include: How do water isotope proxy records capture changes in the tropical water cycle? Where and how well do the modern day temperature-hydrology relationships hold over the last 2k? How do changes in atmospheric conditions relate to changes in oceanic conditions? The Iso2k database will be also be a valuable tool for the wider community, including those researching such topics as isotope-enabled climate model simulations and proxy system modeling.

To facilitate broad use of the database, experts in various proxy archive types developed metadata fields to encode the information needed to accurately and systematically interpret isotope ratios. Proxy records in the database are derived from many archives, including corals, ice cores, fossil groundwater, speleothems, tree ring cellulose, and marine and lacustrine sediments. Annually-banded records have a minimum duration of 30 years, and low-resolution records have a minimum duration of 200 years and at least 5 data points during the past 2kyr. Chronological accuracy standards follow those of the PAGES2k temperature database. Datasets are publicly archived, although unpublished data is accepted in some circumstances. Ultimately, isotope records will be integrated into the larger PAGES 2k database, where they can be searched along with other climate proxies.

In this presentation, we will show initial results of the Iso2k effort. Our goals are to solicit community input into the project and to encourage use of the database to answer questions about the climate of the past two millennia.