About
Aradhna Tripati is a professor at UCLA, serving as the Director and Principal Investigator of the Institute of the Environment and Sustainability (IoES). Her work is highly interdisciplinary, spanning the Institute of the Environment and Sustainability, the Department of Atmospheric and Oceanic Sciences, the Department of Earth, Planetary, and Space Sciences, the Institute for Geophysics and Planetary Physics, and the California Nanosystems Institute. She researches and teaches about climate change, the history and dynamics of Earth systems including climate, ice sheets, oceans, the water cycle, and carbon dioxide levels, as well as tool development and clumped isotope geochemistry. Growing up in Los Angeles, her passion for environmental science was ignited during a college course on Environmental Geology. She has mentored over 130 postdoctoral fellows, researchers, and students at various levels, and has established world-renowned laboratories. Her research has garnered over 3000 citations, and she has published extensively, including in top journals such as Nature, Science, and Proceedings of the National Academy of Sciences. Her lifelong goals include advancing geochemical tracers for Earth system processes, studying climate change history and dynamics, and promoting diversity in environmental science and higher education. Aradhna has received numerous awards for her research, education, and outreach, including the Presidential Early Career Award in Science and Engineering from President Obama, the NSF CAREER award, the Bromery Award for Minorities from the Geological Society of America, and the E.O. Wilson Award for Outstanding Science on climate change. She holds a B.S. in Geological Sciences from California State University, Los Angeles, and a Ph.D. in Earth Sciences from UC Santa Cruz. She was a research fellow at the University of Cambridge and has been a visiting scientist at Caltech. She began her faculty career at UCLA in 2009, receiving tenure in 2014.
Research topics
- Geology
- Mineralogy
- Paleontology
- Geochemistry
- Computer Science
- Biology
- Chemistry
- Metallurgy
- Astrobiology
- Environmental science
- Atmospheric sciences
- Environmental chemistry
- Chromatography
- Nuclear physics
Selected publications
Comment on egusphere-2025-6270
2026-03-31
peer-reviewOpen accessSenior author<strong class="journal-contentHeaderColor">Abstract.</strong> Compilations of proxy data suggest that global temperatures during the Last Glacial Maximum (LGM; ~21,000 years ago) were 3–6 °C cooler than present. However, large-scale proxy syntheses and assimilation products largely focus on the mid- and high-latitude northern hemisphere and marine environments with limited data from low latitudes or terrestrial island settings. Here, we report modern and LGM land snail proxy data from endemic land snails of the Canary Islands (<em>Monilearia monilifera, Theba geminata, and Theba sp.</em>), in the subtropical Atlantic off the coast of Northwest Africa and compare results to LGM paleoclimate model simulations. We apply carbonate clumped paleothermometry, a thermodynamically based environmental tracer, to terrestrial snail shells to constrain mean annual surface air temperature and compare results to climate model simulations from the Paleoclimate Modeling Intercomparison Project (PMIP3 and PMIP4) and from the Hadley Center (HadCM3). Proxy data indicate that LGM mean annual air temperatures ~8.4 °C ± 2.8 °C cooler than estimates from modern land snails, which is cooler than most paleoclimate model estimates. We applied a snail-based proxy system model to reconstruct the oxygen isotope composition of rainfall and show that data are consistent with winter-dominated rainfall with no major changes in water source with respect to present. Our work indicates major glacial cooling in a terrestrial low-latitude ocean island setting that contradicts broader LGM terrestrial temperature reconstructions and simulations.
Quantifying the impacts of rainfall and evaporation on Lake Bonneville
Science Advances · 2026-01-01 · 1 citations
articleOpen accessSenior authorCorrespondingImproved understanding of hydroclimatic drivers in water-stressed regions enables more accurate forecasting of future climate change impacts. Lake Bonneville was the largest Pleistocene lake in western North America, with a maximum surface area of ~52,000 km 2 , before shrinking markedly to become the modern Great Salt Lake. After more than a century of study, the balance between enhanced precipitation and reduced evaporation as drivers of lake growth continues to be debated. Multiple studies identify precipitation as the main factor associated with the highest lake levels, but most proxies provide an estimate of net evaporation and cannot independently resolve precipitation from evaporation. Therefore, factors associated with lake size, growth, and retreat remain uncertain. This study uses the thermodynamically based carbonate clumped isotope geothermometer to estimate temperature, evaporation, and precipitation at Lake Bonneville from 23 to 16 thousand years ago (ka). Clumped isotope derived constraints on hydroclimate are also applied to assess the accuracy of regional climate model outputs. During transgressive and open phases of the lake, we find that regional and large-scale precipitation delivery were the driving factors of lake expansion. In contrast, at its maximum extent (~17.5 ka), Lake Bonneville was maintained via suppressed evaporation rates at 50% relative to modern while precipitation rates were similar to modern levels.
Cenozoic clumped isotope temperature record from the deep North Atlantic v.2
EarthChem Library · 2026-01-01
datasetOpen accessThis is a corrected version. The dataset contains clumped isotope (D47), d18O and d13C data from benthic foraminifera from four IODP sites from the Newfoundland margin. The D47 data were used to reconstruct deep ocean temperature across the Cenozoic era. In this dataset, replicate-level raw data including standard data for correction are provided to allow for reprocessing of the data.
Journal of Sedimentary Research · 2025-10-17
articleABSTRACT Carbonate concretions are zones of preferential cementation in sedimentary rocks. Concretion formation is driven by various biotic or abiotic diagenetic reactions that lead to localized carbonate-mineral saturation. However, many reactions can promote carbonate saturation, lending ambiguity to mechanisms of concretion formation in any given deposit. Large (up to ∼ 2 m across), ellipsoidal carbonate concretions occur in late Miocene (∼ 10 Ma) sandstone turbidites of the Castaic Formation and Ridge Basin Group exposed in Ridge Basin, California, USA. The concretions are absent from shale interbeds, suggesting that the host lithology plays a role in concretion authigenesis. Concretion carbonate carbon-isotope (δ13Ccarb) compositions range from –12.6 to –1.5‰ VPDB, indicating variable carbon contribution from organic sources. Petrographic data and contents of concretion total inorganic carbon (TIC) indicate that cementation occurred after significant burial compaction. Concretion clumped-isotope temperatures and oxygen isotope compositions (δ18Ocarb) range from 45 to 85°C and –13.5 to –11.0‰ VPDB, respectively, and further support relatively hot and deep formation. The average concretion carbonate strontium-isotope composition (87Sr/86Srcarb) of ∼ 0.7117 falls between the 87Sr/86Sr composition of contemporaneous (∼ 10 Ma) seawater and the detrital (noncarbonate cement) fraction contained in the concretions. The 87Sr/86Srcarb values suggest partial Sr incorporation from reactive silicates in the host turbidite sandstones. These findings indicate that concretion formation was deep and likely driven by the reaction of organic-derived CO2 with turbidite silicates, providing sources of calcium and alkalinity for carbonate authigenesis.
Dissolution Effects on Clumped Isotope Signatures in Planktic Foraminifera
Paleoceanography and Paleoclimatology · 2025-10-30 · 1 citations
articleOpen accessSenior authorCorrespondingAbstract The carbonate clumped isotope paleothermometer is becoming more widely used in the geosciences because it is less sensitive to solution δ 18 O and Mg/Ca than other carbonate‐based temperature proxies. Here, we examine the impacts of dissolution on foraminiferal clumped isotope records (Δ 47 ). Dissolution is known to impact carbonate minerals in ocean sediments near and below the carbonate saturation horizon. The effects of dissolution on foraminiferal mass, δ 18 O, and Mg/Ca have been the subject of prior work but have not yet been reported for the carbonate clumped isotope paleothermometer. We examine six planktic foraminiferal species from core‐tops collected at different water depths on the Ontong Java Plateau. Below the carbonate saturation horizon, multiple species exhibit higher Δ 47 values, biasing Δ 47 to cooler temperatures, though all species remain within error of their assumed calcification depth ranges. These effects are observed in Globigerinella siphonifera , Pulleniatina obliquiloculata , and Globorotalia tumida with an ∼0.01‰ difference from above to below the saturation horizon; p < 0.01 corresponding to a temperature bias of ∼4°C at a measured temperature of 28°C and of ∼3°C at a measured temperature of 18°C. Normalizing data for different species yields a pooled slope of −0.0006‰/μmol/kg Δ[CO 3 2− ] ( p < 0.01). Dissolution experiments show that for two species, Trilobus sacculifer and G . tumida , Δ 47 increased with mass loss. We propose multiple mechanisms by which dissolution may impact Δ 47 including intra‐test heterogeneous dissolution, which provide context to enable corrections for the impacts of dissolution on clumped isotope‐based paleo‐records.
2025-01-24 · 1 citations
preprint1st authorCorrespondingThe carbonate ”clumped” isotope thermometer (Δ47) in foraminifera is increasingly being used to reconstruct ocean temperature. Here we address several less understood aspects of the proxy using a large dataset comprising new and reprocessed data. The Δ47-temperature relationship in foraminifera (n = 260) is described by Δ47 = 0.0374 {plus minus} 0.0013 106/T2 + 0.1744 {plus minus}0.0154, and in inorganic calcite (n = 118) by Δ47 = 0.0392 {plus minus} 0.0014 106/T2 + 0.1547 {plus minus}0.0165. Dataset-related differences explain only 11% of the variance; non-thermal effects explain up to 13% of the variance. We address the paucity of benthic data, establishing with more certainty that temperature sensitivity is indistinguishable from planktics and inorganic calcite. The large benthic dataset resolves a previously uncharacterized correlation with [CO32-] that is small (ΔΔ47/ΔCO32- slope = 0.00019 {plus minus}0.00004, n = 66; R2 = 0.315, p <0.01). We report a multivariate regression to account for both temperature and Δ[CO32] for all benthics (epifaunal and infaunal), with Δ47 = 0.152 {plus minus} 0.049 + 0.03865 {plus minus}0.00376 x 106/T2 + 0.000150 {plus minus}0.0000601Δ[CO32-]. We apply these regressions to published Cenozoic benthic Δ47 data, with the multivariate benthic equation yielding temperature and δ18Osw values more consistent with independent proxies, models, and the broader understanding of ocean and cryosphere dynamics under different conditions, including across the Eocene-Oligocene Transition and the Early Eocene Climatic Optimum. In total, this work enables the application of clumped isotopes to foraminifera with a more realistic understanding of uncertainties.
The Depositional Record · 2025-01-24 · 1 citations
articleOpen accessSenior authorCorrespondingAbstract Lacustrine palaeotemperature reconstructions are important for characterising past temperature and hydroclimate change, validating multi‐proxy reconstructions and evaluating global climate models. In particular, lake water temperature is often derived from geochemical proxies—including clumped isotopes (Δ 47 ), oxygen isotopes (δ 18 O), alkenone lipids (U k’ 37 ) and GDGT compounds (TEX 86 ). However, global climate models, constrained by resolution, computational demand and cost, are designed to simulate large‐scale processes, often at the expense of resolving lakes and simulating lake temperature. Consequently, this limitation complicates the comparison of climate model‐simulated variables such as air temperature, with lake water temperature or with other proxy variables (e.g. pollen‐derived air temperature), and requires the use of a transfer function to relate lake temperature to air temperature. Previous work developed transfer functions to translate proxy‐derived seasonal lake water temperature to mean annual air temperature using ground‐based measurements from 88 lakes. This study reports new lake‐to‐air temperature transfer functions (for annual, spring through summer, spring, summer and warmest month) that incorporate lake surface water temperature, and new variables including latitude and elevation, by analysing climate reanalysis data and long‐term satellite observations of surface temperatures for 1395 modern lakes via regression‐based inverse modelling. With the use of multiple regression models and a dataset roughly 10 times larger, the error in predictions of mean annual air temperature is reduced by up to 48% compared to previous work. To demonstrate the potential of the new transfer functions for integrating and comparing proxy data with model output, Pliocene and Pleistocene mean annual air temperature was reconstructed from Δ 47 ‐derived lake temperatures and compared with model simulations for the Last Glacial Maximum and mid‐Piacenzian warm period. The new transfer functions, with reduced error, should enable more accurate palaeotemperature reconstructions from proxy‐derived lake water temperature and allow for more comprehensive assessments of climate model skill.
Dissolution effects on clumped isotope signatures in planktic foraminifera
2025-01-31
preprintOpen accessSenior authorThe carbonate clumped isotope paleothermometer is becoming more widely used in the geosciences because it is less sensitive to solution δ 18 O and Mg/Ca than other carbonate-based temperature proxies. Here, we examine the impacts of dissolution on foraminiferal clumped isotope records (∆ 47 ). Dissolution is known to impact carbonate minerals in ocean sediments near and below the carbonate saturation horizon. The effects of dissolution on foraminiferal mass, δ 18 O, and Mg/Ca have been the subject of prior work but have not yet been reported for the carbonate clumped isotope paleothermometer. We examine six planktic foraminiferal species from core-tops collected at different water depths on the Ontong Java Plateau. Below the carbonate saturation horizon, multiple species exhibit higher ∆ 47 values, likely due to dissolution, biasing ∆ 47 to cooler temperatures. The largest effects are observed in G. siphonifera , P. obliquiloculata , and G. tumida with an ~0.01 ‰ difference from above to below the saturation horizon; p < 0.01 corresponding to a temperature bias of ~4 °C at a measured temperature of 28 °C and of ~3 °C at a measured temperature of 18 °C. Normalizing data for different species yields a pooled slope of -0.0006 ‰/µmol/kg ∆[CO 3 2- ] (p < 0.01). Dissolution experiments show that for two species, T. sacculifer and G. tumida , ∆ 47 increased with mass loss. We propose multiple mechanisms by which dissolution may impact ∆ 47 including intra-test heterogeneous dissolution, which provide context to enable corrections for the impacts of dissolution on clumped isotope-based paleo-records.
Journal of Mammalian Evolution · 2025-01-14 · 15 citations
articleOpen accessAbstract Remains of megatheres have been known since the 18th -century and were among the first megafaunal vertebrates to be studied. While several examples of preserved integument show a thick coverage of fur for smaller ground sloths living in cold climates such as Mylodon and Nothrotheriops , comparatively very little is known about megathere skin. Assuming a typical placental mammal metabolism, it was previously hypothesized that megatheres would have had little-to-no fur as they achieved giant body sizes. Here the “hairless model of integument” is tested using geochemical analyses to estimate body temperature to generate novel models of ground sloth metabolism, fur coverage, and paleoclimate with Niche Mapper software. The simulations assuming metabolic activity akin to those of modern xenarthrans suggest that sparse fur coverage would have resulted in cold stress across most latitudinal ranges inhabited by extinct ground sloths. Specifically, Eremotherium predominantly required dense 10 mm fur with implications for seasonal changes of coat depth in northernmost latitudes and sparse fur in the tropics; Megatherium required dense 30 mm fur year-round in its exclusive range of cooler, drier climates; Mylodon and Nothrotheriops required dense 10–50 mm fur to avoid thermal stress, matching the integument remains of both genera, and further implying the use of behavioral thermoregulation. Moreover, clumped isotope paleothermometry data from the preserved teeth of four genera of ground sloth yielded reconstructed body temperatures lower than those previously reported for large terrestrial mammals (29 ± 2°–32 ± 3° C). This combination of low metabolisms and thick fur allowed ground sloths to inhabit various environments.
Journal of Mammalian Evolution · 2025-02-12
articleOpen accessof four genera of ground sloth yielded reconstructed body temperatures lower than those previously reported for large terrestrial mammals (29 2-32 3 C).This combination of low metabolisms and thick fur allowed ground sloths to inhabit various environments."2. The name of the artist in the caption of Fig. 9 that written as "Syed Jaffri H" should be corrected to "Haider Syed Jaffri." 3. The "UF 312,730" found in the first paragraph, second column of page 19 of 24 of the proof should be corrected to "UF 312730."4.
Recent grants
RAISE: Bringing Together Diverse Perspectives on Water
NSF · $1.3M · 2019–2025
NSF · $236k · 2012–2014
Collaborative Research: EAGER: A cross-institution Veterans in Green STEM program
NSF · $181k · 2020–2022
NSF · $1.9M · 2023–2028
NSF · $390k · 2011–2014
Frequent coauthors
- 321 shared
Robert A. Eagle
University of California, Los Angeles
- 99 shared
Jamie Lucarelli
Center for Creative Leadership
- 95 shared
Victoria A. Petryshyn
- 94 shared
Maxence Guillermic
University of California, Los Angeles
- 84 shared
Ben Elliott
- 75 shared
Yama Dixit
Indian Institute of Technology Delhi
- 61 shared
Alexandrea Arnold
NOAA Oceanic and Atmospheric Research
- 61 shared
S. J. Loyd
California State University, Fullerton
Labs
Not provided
Education
Ph.D., Environmental Science and Engineering
University of California, Los Angeles
M.S., Environmental Science and Engineering
University of California, Los Angeles
B.S., Environmental Science
University of California, Los Angeles
Awards & honors
- Presidential Early Career Award in Science and Engineering f…
- NSF CAREER award
- Bromery Award for Minorities from the Geological Society of…
- Hellman Fellow
- National Academy of Sciences Kavli Fellow
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