About

Kaustubh Thirumalai is an Associate Professor in the Department of Geosciences at the University of Arizona. He obtained his Ph.D. in 2016 at the University of Texas at Austin and joined the university faculty in 2019 after completing postdoctoral positions at the UT Institute for Geophysics and Brown University’s Department of Earth, Environmental, and Planetary Sciences. His research focuses on Earth's climate variability and paleoceanography, aiming to understand the causes and mechanisms of past fluctuations in the ocean and atmosphere, and how this information can help anticipate future changes. He employs a combination of observations, geochemical proxy measurements, and modeling simulations to investigate important processes in the Earth-climate system, primarily involving stable isotopic and trace metal geochemistry of carbonate archives such as corals, foraminifera, snails, and stalagmites, as well as climate model analyses. Thirumalai is also interested in extreme climate events and hazards, including earthquakes, flooding, heatwaves, and sea-level changes, and how the geological record can inform future projections. His ongoing research projects include Indo-Pacific climate change, Atlantic Ocean circulation anomalies, Indian paleomonsoon variability, and proxy-model comparison uncertainties. Thirumalai has received numerous awards and recognitions, including the 2026 National Fellowship on the Future of Liberal Education, the 2025 Fellow National of The Explorers Club, and the 2022 AGU Nanne Weber Early Career Award, among others.

Research topics

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

Selected publications

• The PhanSST global database of Phanerozoic sea surface temperature proxy data

  Scientific Data · 2022 · 40 citations

  • Computer Science
  • Geology
  • Database

  Paleotemperature proxy data form the cornerstone of paleoclimate research and are integral to understanding the evolution of the Earth system across the Phanerozoic Eon. Here, we present PhanSST, a database containing over 150,000 data points from five proxy systems that can be used to estimate past sea surface temperature. The geochemical data have a near-global spatial distribution and temporally span most of the Phanerozoic. Each proxy value is associated with consistent and queryable metadata fields, including information about the location, age, and taxonomy of the organism from which the data derive. To promote transparency and reproducibility, we include all available published data, regardless of interpreted preservation state or vital effects. However, we also provide expert-assigned diagenetic assessments, ecological and environmental flags, and other proxy-specific fields, which facilitate informed and responsible reuse of the database. The data are quality control checked and the foraminiferal taxonomy has been updated. PhanSST will serve as a valuable resource to the paleoclimate community and has myriad applications, including evolutionary, geochemical, diagenetic, and proxy calibration studies.

  PublisherOA PDFDOI

• Rapid and precise measurement of carbonate clumped isotopes using laser spectroscopy

  Science Advances · 2022 · 28 citations

  • Mineralogy
  • Chemistry
  • Geology

  produced by digestion of 51 synthetic carbonates equilibrated at 6° to 1100°C is consistent with results for natural carbonates and previous calibrations. Our system results were indistinguishable from IRMS systems after replicating the InterCarb interlaboratory calibration. Measurement by TILDAS could change the landscape for clumped isotope analysis.

  DOI

• Remote and local drivers of Pleistocene South Asian summer monsoon precipitation: A test for future predictions

  Science Advances · 2021 · 138 citations

  • Climatology
  • Environmental science
  • Physical geography

  South Asian precipitation amount and extreme variability are predicted to increase due to thermodynamic effects of increased 21st-century greenhouse gases, accompanied by an increased supply of moisture from the southern hemisphere Indian Ocean. We reconstructed South Asian summer monsoon precipitation and runoff into the Bay of Bengal to assess the extent to which these factors also operated in the Pleistocene, a time of large-scale natural changes in carbon dioxide and ice volume. South Asian precipitation and runoff are strongly coherent with, and lag, atmospheric carbon dioxide changes at Earth's orbital eccentricity, obliquity, and precession bands and are closely tied to cross-equatorial wind strength at the precession band. We find that the projected monsoon response to ongoing, rapid high-latitude ice melt and rising carbon dioxide levels is fully consistent with dynamics of the past 0.9 million years.

  DOI

• Lessons from a high-CO ₂ world: an ocean view from  ∼ 3 million years ago

  Climate of the past · 2020 · 134 citations

  • Climatology
  • Environmental science
  • Oceanography

  Abstract. A range of future climate scenarios are projected for high atmospheric CO2 concentrations, given uncertainties over future human actions as well as potential environmental and climatic feedbacks. The geological record offers an opportunity to understand climate system response to a range of forcings and feedbacks which operate over multiple temporal and spatial scales. Here, we examine a single interglacial during the late Pliocene (KM5c, ca. 3.205±0.01 Ma) when atmospheric CO2 exceeded pre-industrial concentrations, but were similar to today and to the lowest emission scenarios for this century. As orbital forcing and continental configurations were almost identical to today, we are able to focus on equilibrium climate system response to modern and near-future CO2. Using proxy data from 32 sites, we demonstrate that global mean sea-surface temperatures were warmer than pre-industrial values, by ∼2.3 ∘C for the combined proxy data (foraminifera Mg∕Ca and alkenones), or by ∼3.2–3.4 ∘C (alkenones only). Compared to the pre-industrial period, reduced meridional gradients and enhanced warming in the North Atlantic are consistently reconstructed. There is broad agreement between data and models at the global scale, with regional differences reflecting ocean circulation and/or proxy signals. An uneven distribution of proxy data in time and space does, however, add uncertainty to our anomaly calculations. The reconstructed global mean sea-surface temperature anomaly for KM5c is warmer than all but three of the PlioMIP2 model outputs, and the reconstructed North Atlantic data tend to align with the warmest KM5c model values. Our results demonstrate that even under low-CO2 emission scenarios, surface ocean warming may be expected to exceed model projections and will be accentuated in the higher latitudes.

  DOI

• Future exacerbation of hot and dry summer monsoon extremes in India

  npj Climate and Atmospheric Science · 2020 · 138 citations

  • Climatology
  • Environmental science
  • Atmospheric sciences

  Abstract Summer monsoon (June-September) precipitation is crucial for agricultural activities in India. Extremes during the monsoon season can have deleterious effects on water availability and agriculture in the region. Here, we show that hot and dry extremes during the summer monsoon season significantly impact food production in India and find that they tend to occur during El Niño years during the observed record of 1951–2018. We then use an ensemble of climate simulations for the historic (1971–2000) and future (2006–2100) that capture this coupling between El Niño and the Indian monsoon to show that the frequency of concurrent hot and dry extremes increases by a factor of 1.5 under continued greenhouse warming during the 21st century. Despite projections of summer monsoon intensification on the order of ~10%, the rise in surface air temperatures as well as increase in rainfall variability contributes to more severe hot and dry monsoon extremes over India, thereby posing a substantial challenge to future food security in India.

  DOI

• Past climates inform our future

  Science · 2020 · 643 citations

  • Computer Science
  • Environmental science
  • Climatology

  As the world warms, there is a profound need to improve projections of climate change. Although the latest Earth system models offer an unprecedented number of features, fundamental uncertainties continue to cloud our view of the future. Past climates provide the only opportunity to observe how the Earth system responds to high carbon dioxide, underlining a fundamental role for paleoclimatology in constraining future climate change. Here, we review the relevancy of paleoclimate information for climate prediction and discuss the prospects for emerging methodologies to further insights gained from past climates. Advances in proxy methods and interpretations pave the way for the use of past climates for model evaluation-a practice that we argue should be widely adopted.

  DOI

Recent grants

• Collaborative Research: Testing the Indian Ocean El Nino Hypothesis

  NSF · $395k · 2019–2023

• Collaborative Research: P2C2--Variability, Impacts and Extremes of the ENSO-Asian Monsoon Relationship over the Common Era

  NSF · $46k · 2021–2023

• Collaborative Research: P2C2--Subdecadal Pleistocene Indian Monsoon Variability: A Dual Archive Perspective

  NSF · $417k · 2021–2024

Frequent coauthors

• Terrence M. Quinn

  The University of Texas at Austin

  40 shared

• J. W. Partin

  The University of Texas at Austin

  34 shared

• Steven C. Clemens

  Brown University

  29 shared

• Jessica E. Tierney

  University of Arizona

  24 shared

• Philippe Martinez

  Université de Bordeaux

  23 shared

• Julie N. Richey

  United States Geological Survey

  22 shared

• Liviu Giosan

  20 shared

• Chuan–Chou Shen

  National Taiwan University

  19 shared

Education

• Ph.D., Institute for Geophysics & Department of Geological Sciences

  The University of Texas at Austin

  2016

• MS, Institute for Geophysics & Department of Geological Sciences

  The University of Texas at Austin

  2012

• B. Tech, Department of Chemical Engineering

  National Institute of Technology Karnataka

  2010

Awards & honors

• 2026 National Fellowship on the Future of Liberal Education…
• 2025 Fellow National, The Explorers Club
• 2022 AGU Nanne Weber Early Career Award
• 2022 University of Arizona Geosciences Outstanding Faculty A…
• 2021 AGU Outstanding Reviewer for 2020, Geophysical Research…

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