Research
Themes
My group’s research focuses on paleoclimatology – the study of past climates – along the following themes. For more details, see our publications.
Climate Reconstruction
Climate Modeling

Our group has participated in the development [10] and evaluation of climate models, examining how models represent ENSO [11], simulate volcanic eruptions [12], fractionate water isotopes [13,14], and simulate the climate continuum [15]. Paleoclimatology is particularly suited for model evaulation, as past climates provide an out-of-sample test of model predictions. Picture credit: Quanta Magazine.
Data Science
Proxy Interpretation
Open Science
Current Projects
LMR4D: P4CLIMATE — Connecting Seasonal to Millennial Timescales through Strongly Coupled Data Assimilation
LMR4D is the latest iteration of the Last Millennium Reanalysis implementing a 4D variational (4DVAR) data assimilation framework — the same approach used in operational numerical weather prediction — to produce seasonally resolved temperature reconstructions over the Common Era. LMR4D will leverage data from new sources, including documentary evidence, marine sediments, annually-resolved marine bivalve chronologies, as well as boreholes. The resulting seasonally resolved reconstruction will be applied to (A1) simulate tropical cyclone track and intensity statistics using deep-learning weather models (Pangu-Weather, FourCastNet, DLWP), extending TC records by centuries and enabling the first millennial-scale simulations of tropical cyclone statistics, and (A2) characterize sources of climate variability across the seasonal-to-centennial continuum, including volcanic forcing responses and constraints on equilibrium climate sensitivity. LMR4D products will be publicly accessible via PReSto and NOAA NCEI; the 4DVAR algorithm and proxy system models will be shared on GitHub, with reproducible workflows distributed via PaleoBooks. The project is training two graduate students and several undergraduates.
NSF Award Page | Publications: [36,37]
PaleoPAL: An AI Research Assistant for Paleoclimatology
PaleoPAL leverages a Retrieval-Augmented Generation (RAG) – Large Language Model (LLM) framework to create an AI assistant for paleoclimatology, enabling scientists to search for datasets, methods, and workflows appropriate to their research problem directly from a Jupyter Notebook. The project targets three critical research areas: placing recent El Niño variations in the context of the last 10,000 years, detecting climate tipping points and their potential precursors, and generating empirically-based, low-cost climate projections. By embedding AI directly into the practice of paleoclimatology through a familiar Jupyter interface, PaleoPAL aims to lower technical and conceptual barriers to sophisticated analyses across the paleoclimate community.
PaleoCube: Enabling Cloud-Based Paleoclimatology
PaleoCube proposes to lower technical and social barriers that prevent full use of paleoclimate observations by bringing scientists to work in the Cloud. The project extends existing cyberinfrastructure (LinkedEarth, Pangeo, Jupyter) to bring cutting-edge capabilities to paleoclimate scientists through cloud-based workflows, hackathons, and community engagement.
NSF Award Page | [22,38] | CyberPaleo | PaleoBook Gallery
PReSto: A Paleoclimate Reconstruction Storehouse
Developing a continuously-updated platform for paleoclimate reconstructions with broad web access to accelerate scientific inference. PReSto will connect growing digital paleoclimate data to evolving methodologies and distribute results through responsive web interfaces.
Past Projects
FROGS: Facilitating Reproducible Open GeoScience
NSF GEO OSE Track 1 RISE-2324732 | Co-PI (Lead: D. Khider, ISI) | 2024-2026
Building open science capacity in the geosciences through the LeapFROGS training platform and a series of hands-on workshops (PyRATES, FAIRLeap, Open Geoscience Hackathon). Three workshops engaged 56 participants across more than a dozen geoscience subfields and career stages, producing 8 reproducible notebooks and 9 open-source software packages. Post-event surveys showed over 90% of participants gained confidence in applying FAIR and reproducible research methods.
A Big Data Approach to Fundamental Paleoclimate Questions
Applying Big Data approaches to address fundamental questions in climate dynamics: (1) the spatial extent of abrupt changes in hydroclimate, and (2) how knowledge of past temperature variations can help reduce uncertainty in twenty-first century climate projections. Links paleoclimate data to CMIP6 climate model projections.
The Global Climate Response to Volcanic Eruptions
NOAA Climate Program Office NA18OAR4310426 | Lead PI | 2018-2020
Investigating volcanic climate impacts using the Last Millennium Reanalysis framework.
Abrupt Change in Climate and Ecosystems
International collaboration investigating tipping points in climate and ecosystems through integrated analysis approaches. Part of the Belmont Forum’s focus on understanding where critical thresholds exist in Earth system components.
LinkedEarth: Crowdsourcing Data Curation & Standards
NSF EarthCube ICER 1541029 | Lead PI | 2015-2017
Community platform development for paleoclimate data standards and knowledge curation.
Last Millennium Climate Reanalysis Project
NOAA Climate Program Office NA14OAR4310175 | Co-PI (Lead: G. Hakim, UW) | 2014-2017
Developing data assimilation methods for paleoclimate reconstructions over the Common Era.
GeoChronR: Open-Source Tools for Time-Uncertain Data
NSF Geoinformatics EAR 1347213 | Co-PI (Lead: N. McKay, NAU) | 2014-2017
Analysis, visualization and integration tools for geochronological data with age uncertainties.
Efficient High Dimensional Bayesian Methods for Climate Field Reconstruction
NSF Mathematical Geophysics DMS 1025464 | Co-PI (Lead: B. Rajaratnam, Stanford) | 2010-2015
Statistical method development for spatially complete climate reconstructions.
Multiproxy Reconstructions as A Missing-Data Problem
NSF P2C2 GEO 1003818 | Lead PI | 2010-2015
New techniques for multiproxy climate reconstructions and their application to regional climates of the past millennium.
Maximizing the Potential of Tropical Climate Proxies
NOAA Climate Program Office NA10OAR4310115 | Lead PI | 2010-2014
Integrated climate-proxy forward modeling to maximize the climate information extractable from tropical paleoclimate proxies.
References
cfr (v2024.1.26): A python package for climate field reconstruction. Geoscientific Model Development. 2024;17(8):3409–31. doi:10.5194/gmd-17-3409-2024


