About

Jessica Tierney is a Professor and the Thomas R. Brown Distinguished Chair in Integrative Science in the Department of Geosciences at the University of Arizona. She specializes in the study of past climate change (paleoclimatology) using organic geochemistry, climate modeling, and statistical climate reconstruction. Her research focuses on understanding historical climate variations to inform current climate science. Jessica Tierney has received numerous awards and recognitions, including the National Science Foundation Alan T. Waterman Award in 2022, the Packard Fellowship in Science and Engineering from 2015 to 2020, and the James B. Macelwane Medal from the American Geophysical Union in 2014. She is recognized for her contributions to climate science and organic geochemistry, and she holds a prominent position within the Department of Geosciences at the University of Arizona.

Research topics

• Geology
• Oceanography
• Environmental science
• Climatology
• Geography
• Atmospheric sciences
• Computer Science
• Meteorology
• Database
• Environmental resource management
• Physical geography
• Paleontology
• Ecology
• World Wide Web
• Archaeology
• Physics
• Business
• Earth science
• Biology

Selected publications

• jesstierney/BAYMAG: version 1.2

  Zenodo (CERN European Organization for Nuclear Research) · 2026-02-08

  otherOpen access1st authorCorresponding

  Release to accompany Zenodo integration.

  PublisherDOI

• GDGT calibration database and forward posteriors for TEXAS (texas-psm)

  Zenodo (CERN European Organization for Nuclear Research) · 2026-05-04

  datasetOpen access

  Pre-computed Baysian forward calibration posteriors (.nc) and the GDGT training database used in Rattanasriampaipong et al. (in prep). Required for running inverse temperature reconstructions with the texas-psm python package.

  PublisherDOI

• Plant Wax Isotopic Reconstructions Reveal Thermodynamic Drivers of Hydroclimate Over the Last Two Glacial Cycles at Great Salt Lake and Bear Lake, Utah

  Paleoceanography and Paleoclimatology · 2026-01-29

  articleOpen access

  Abstract The growth and decay of the Laurentide ice sheet altered the hydrological cycle over southwestern North America. While it is well‐documented that the last glacial was wetter and had isotopically lighter precipitation, much less information is available for prior glacials. Increased proxy coverage is needed to test climate models' ability to reconstruct these changes and to assess their predictive power for water availability in response to future climate change. Here, we present parallel precipitation isotope records spanning the last two glacial cycles from two large, proximal lakes in Utah, USA: Great Salt Lake and Bear Lake. We use plant wax n ‐alkane δD as a proxy for precipitation δD (δD precip ) and find coherent glacial‐interglacial fluctuations in δD precip , with a ∼30‰ D‐depletion during glacial maxima relative to interglacials. We find similar δD precip values between the Holocene and Eemian, but at the lower‐pCO 2 MIS 7 interglacial, D‐enrichment is only weakly recorded at Great Salt Lake and absent at higher elevation Bear Lake. Comparison to regional proxy archives finds large‐scale coherence in regional hydroclimate change over the last two glacial cycles is best explained by thermodynamic processes, with increased rainout efficiency, isotopic fractionation, and snow in a colder atmosphere. Comparison of proxies to climate model experiments showed models considerably underestimate glacial lowering of precipitation isotopic values, but overestimate inland Rayleigh distillation. New and assembled proxy reconstructions provide greater temporal and spatial coverage as targets for model skill in capturing hydroclimate variations across the past two glacial cycles.

  PublisherOA PDFDOI

• The Glacial-Interglacial CO$_2$-Temperature Relationship

  2026-02-10

  articleOpen accessSenior author

  The slope $S$ of the global mean surface temperature (GMST)–atmospheric carbon dioxide (CO$_2$) relationship, sometimes termed Earth system sensitivity, is a holistic measure of Earth’s response to radiative forcings. We identify a surprising trend in $S$ over the past 800kyr, when it reflects the net carbon cycle feedback’s response to GMST changes. We estimate $S$ roughly doubled over this period. This trend is robust to record completeness and age error, and across multiple GMST reconstructions and proxy types. However, site-specific records do not show increasing temperature variability relative to CO$_2$. This implies either age errors are substantially underestimated, or local variations in temperature became more synchronized over the more recent glacial-interglacial cycles, possibly via a strengthening ice-albedo feedback. Either way, our findings indicate GMST fluctuated more per unit CO$_2$ change over the past several glacial-interglacial cycles than the Cenozoic or Phanerozoic average.

  PublisherOA PDFDOI

• jesstierney/BAYSPLINE: Version 1.1a

  Open MIND · 2026-02-09 · 1 citations

  other1st authorCorresponding

  Version release for Zenodo integration

  DOI

• Biomarker-based  limnology of Great Salt Lake over the last two glacial cycles

  2026-01-06 · 1 citations

  articleOpen access

  Great Salt Lake (GSL), Utah, USA, is a large hypersaline lake currently experiencing desiccation due to water use and evaporation exceeding recharge. At times in the past it has been an expansive freshwater lake, the remnants of which are still visible on the landscape as the Bonneville Salt Flats. The long-term history of the lake beyond the present and highstand shorelines can be further explored with sediment cores drilled by the Global Lakes Drilling (GLAD) project in 2000 recovering sediment down to 120 m below lake floor. We update the age model with new uranium-series measurements on aragonite-rich sediment layers and halite deposits. The new dating helps constrain the timing of events around glacial terminations and in the lower half of the core as well as provide a new bottom core age of 236.3 ka (2σ = 6.7 kyr), capturing the penultimate interglacial period rarely recorded in continental archives. We measure the abundances of microbial membrane lipids (glycerol dialkyl glycerol tetraethers; GDGTs) and n -alkanoic acids to reconstruct aspects of aquatic productivity, ecology, and limnology at GSL over the last two glacial cycles. While the extreme hypersalinity of GSL impedes interpretations of GDGTs as a proxy for temperature, there are many other indicators of lake salinity, stratification, and productivity that can be investigated using this compound class. We detect lake freshening corresponding to the expanded lake phases named “Bonneville” (last glacial) and “Little Valley” (penultimate glacial), with new U-series ages constraining them to ~25 ka (2σ = 3 kyr) and ~138 ka (2σ = 5.6 kyr), respectively. For the penultimate interglacial, we find limnological conditions at GSL are similar to those outside of the expanded lake phases. Coincident with freshening, GDGTs and n -alkanoic acids show increases in aquatic productivity and more vigorous lake overturning. The times of expanded lakes at GSL coincide with periods of increased moisture recorded in other regional archives, specifically lake highstands and higher water table elevation, in turn driven by climate forcing.

  PublisherDOI

• TEXAS: TetraEther indeX of Ammonia oxidizerS (texas-psm)

  Open MIND · 2026-05-05

  otherOpen access

  TEXAS (texas-psm) is a Python package using Bayesian calibration for marine GDGTs and environmental predictors using Stan. It implements a two-stage workflow: Forward calibration: Fit a generalized logistic curve (Ring Index → temperature) to culture, mesocosm, and coretop isoGDGT data using hierarchical Bayesian Stan models. Outputs a compressed posterior .nc file. Inverse reconstruction (invT): Predict paleotemperatures from new Ring Index observations by marginalising over posterior parameter draws. Returns a full posterior temperature distribution per sample. Optional non-thermal corrections for GDGT-2/3 ratio and NO₃ concentration are supported. The package ships 20 Stan models covering univariate and multivariate variants, direct (marginal) and ensemble sampling, and hard/unconstrained temperature constraints.

  PublisherDOI

• TEXAS: TetraEther indeX of Ammonia oxidizerS (texas-psm)

  Zenodo (CERN European Organization for Nuclear Research) · 2026-04-20

  otherOpen access

  TEXAS (texas-psm) is a Python package using Bayesian calibration for marine GDGTs and environmental predictors using Stan. It implements a two-stage workflow: Forward calibration: Fit a generalized logistic curve (Ring Index → temperature) to culture, mesocosm, and coretop isoGDGT data using hierarchical Bayesian Stan models. Outputs a compressed posterior .nc file. Inverse reconstruction (invT): Predict paleotemperatures from new Ring Index observations by marginalising over posterior parameter draws. Returns a full posterior temperature distribution per sample. Optional non-thermal corrections for GDGT-2/3 ratio and NO₃ concentration are supported. The package ships 20 Stan models covering univariate and multivariate variants, direct (marginal) and ensemble sampling, and hard/unconstrained temperature constraints.

  PublisherDOI

• jesstierney/BAYSPAR: Version 1.2

  Open MIND · 2026-02-08 · 1 citations

  other1st authorCorresponding

  Release to accompany Zenodo integration

  DOI

• Biomarker-based  limnology of Great Salt Lake over the last two glacial cycles

  2026-01-03

  articleOpen access

  Great Salt Lake (GSL), Utah, USA, is a large hypersaline lake currently experiencing desiccation due to water use and evaporation exceeding recharge. At times in the past it has been an expansive freshwater lake, the remnants of which are still visible on the landscape as the Bonneville Salt Flats. The long-term history of the lake beyond the present and highstand shorelines can be further explored with sediment cores drilled by the Global Lakes Drilling (GLAD) project in 2000 recovering sediment down to 120 m below lake floor. We update the age model with new uranium-series measurements on aragonite-rich sediment layers and halite deposits. The new dating helps constrain the timing of events around glacial terminations and in the lower half of the core as well as provide a new bottom core age of 236.3 ka (2σ = 6.7 kyr), capturing the penultimate interglacial period rarely recorded in continental archives. We measure the abundances of microbial membrane lipids (glycerol dialkyl glycerol tetraethers; GDGTs) and n -alkanoic acids to reconstruct aspects of aquatic productivity, ecology, and limnology at GSL over the last two glacial cycles. While the extreme hypersalinity of GSL impedes interpretations of GDGTs as a proxy for temperature, there are many other indicators of lake salinity, stratification, and productivity that can be investigated using this compound class. We detect lake freshening corresponding to the expanded lake phases named “Bonneville” (last glacial) and “Little Valley” (penultimate glacial), with new U-series ages constraining them to ~25 ka (2σ = 3 kyr) and ~138 ka (2σ = 5.6 kyr), respectively. For the penultimate interglacial, we find limnological conditions at GSL are similar to those outside of the expanded lake phases. Coincident with freshening, GDGTs and n -alkanoic acids show increases in aquatic productivity and more vigorous lake overturning. The times of expanded lakes at GSL coincide with periods of increased moisture recorded in other regional archives, specifically lake highstands and higher water table elevation, in turn driven by climate forcing.

  PublisherOA PDFDOI

Recent grants

• Collaborative Research: A Combined Proxy and Model Investigation of Late Holocene Paleoclimate in the Horn of Africa

  NSF · $67k · 2016–2017

• Collaborative Research: A paleoclimate perspective on the response of Southwest North American rainfall to elevated greenhouse gases

  NSF · $63k · 2019–2022

• Collaborative research: Validation of the Lacustrine Branched GDGT Paleothermometer

  NSF · $225k · 2015–2019

• Collaborative Research: A Combined Proxy and Model Investigation of Late Holocene Paleoclimate in the Horn of Africa

  NSF · $524k · 2012–2016

• Molecular views of past changes in the North American Monsoon

  NSF · $505k · 2017–2023

Frequent coauthors

• James M. Russell

  Brown University

  46 shared

• Jiang Zhu

  Climate and Global Dynamics Laboratory

  41 shared

• Jaap S. Sinninghe Damsté

  Royal Netherlands Institute for Sea Research

  38 shared

• Tripti Bhattacharya

  Syracuse University

  34 shared

• Lee R. Kump

  Pennsylvania State University

  31 shared

• Delia W Oppo

  30 shared

• Kevin J. Anchukaitis

  University of Arizona

  29 shared

• Bette L. Otto‐Bliesner

  NSF National Center for Atmospheric Research

  29 shared

Awards & honors

• The National Science Foundation Alan T. Waterman Award (2022…
• Packard Fellowship in Science and Engineering (2015-2020)
• The University of Arizona College of Science Galileo Circle…
• The University of Arizona Department of Geosciences Outstand…
• The University of Arizona Honors College Excellence in Teach…