About

Professor John A. Higgins is a faculty member in the Department of Geosciences at Princeton University, where he leads the Higgins Research Laboratory. His primary research interest is the evolution of the carbon cycle and the global climate system over Earth history. He focuses on processes that control the chemical composition of seawater and how these processes have changed on geologic timescales. Additionally, he studies how the chemistry of carbonate sediments is affected by post-depositional processes such as early diagenetic recrystallization, dolomitization, and hydrothermal alteration. Professor Higgins employs a variety of tools in his research, including numerical models of chemical and isotopic biogeochemical cycles, analysis of traditional stable isotopes of oxygen and carbon, and the application of new isotope systems such as magnesium, calcium, and potassium. His work contributes to understanding the complex interactions within Earth's climate and geochemical systems, shedding light on the history of Earth's climate and biogeochemical processes.

Research topics

• Geology
• Chemistry
• Paleontology
• Geochemistry
• Oceanography
• Environmental chemistry
• Environmental science
• Ecology
• Materials science
• Earth science
• Physics
• Mineralogy
• Biology

Selected publications

• Expert elicitation on agricultural enhanced weathering reveals carbon dioxide removal potential and uncertainties in loss pathways

  Communications Earth & Environment · 2026-03-12

  articleOpen access

  Abstract Enhanced weathering in agriculture is a potential gigatonne-scale carbon dioxide removal (CDR) pathway, but its potential remains difficult to constrain. We used a formal expert elicitation process to estimate CDR potential and efficiency, uncertainties, and key data needs for six feedstocks. Expert opinion of global potential varied by feedstock, with estimates averaging 0.2-0.7 Gt CO2e/yr, but with a wide range (from a source to greater than 5 Gt CO2e/yr removal). When focusing on the American Midwest (pH 5.5-6), carbon dioxide removal efficiency, meaning the fraction of potential ultimately realized, ranged from 27-39%. Key uncertainties included feedstock availability, calcite saturation, and deep soil/freshwater emission pathways. There is a need for empirical data in key stages, with potential to leverage liming data where appropriate. Overall, there appears to be strong potential CDR at broad scales. However, continued research is necessary to build confidence when quantifying that potential and actual removals.

  PublisherOA PDFDOI

• Quantifying changes in central Vietnam rainfall amount since the Late Pleistocene

  Earth and Planetary Science Letters · 2025-11-29 · 2 citations

  article
  PublisherDOI

• Combined Nitrogen and Calcium isotopes in Tyrannosaur tooth enamel reveal minor ontogenetic dietary trends

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

• Decentralized Research Data Management Using Web3 Protocols

  2025-07-27

  report1st authorCorresponding
  PublisherDOI

• Calcium isotope constraints on Mesoarchean seawater

  2025-04-24

  preprintOpen accessSenior author

  The cause of the Great Oxidation Event ~2.4 billion-years-ago (Ga) is hotly debated. Recent models favor the emergence of continents as driving the event. However, we suggest that extensive shallow-marine carbonate platforms existed in the Mesoarchean. This conclusion is based on Ca isotopes from 2.8 Ga carbonate rocks, that constrains the Ca isotope value of Mesoarchean seawater to -0.5‰ relative to present day values. This estimate is strikingly similar to pre-Mesozoic values, suggesting that continental freeboard and the area of carbonate platforms was relatively consistent through most of Earth history. Shallow-marine environments were not only extensive in the Mesoarchean, but carbonate Ce anomalies and Mn concentrations indicate that sedimentary conditions for organic carbon burial existed prior to the rise of atmospheric oxygen.

  PublisherOA PDFDOI

• Disentangling global geochemical signals from local diagenetic alteration in shallow-water marine carbonates during OAE1a

  Earth and Planetary Science Letters · 2025-06-20 · 1 citations

  articleSenior author
  PublisherDOI

• Miocene and Pliocene ice and air from the Allan Hills blue ice area, East Antarctica

  2025-02-07 · 2 citations

  preprintOpen access1st authorCorresponding

  Antarctic ice cores provide a unique archive of Earth's atmosphere and its largest ice sheet. The oldest continuous Antarctic ice core extends to 800,000 years before present, though discontinuous ice cores from the Allan Hills Blue Ice Area (BIA) have been shown to preserve snapshots of ice and air back to at least 2.7 million years ago (Ma). Here we

  PublisherOA PDFDOI

• An extensive Mesoarchean shallow marine carbonate factory

  2025-01-01

  articleSenior author
  PublisherDOI

• 81Kr dating of 1 kg Antarctic ice

  Nature Communications · 2025-05-12 · 2 citations

  articleOpen access

  Recovering earth’s climate history from ice cores requires reliable dating of the ice. 81Kr is ideal for radiometric dating up to more than one million years, but the isotope is so rare that it has long been a challenge to apply 81Kr dating on ice cores where sample size is limited. Here, we show 81Kr dating of 1-kg ice-core samples from Taylor Glacier, Antarctica. This is made possible by an advance in 81Kr detection with an all-optical realization of Atom Trap Trace Analysis. The achieved sample-size reduction facilitates 81Kr dating of basal ice-core sections with direct implications for open questions in paleoclimatology, such as the evolution of glaciers on the Tibetan Plateau or the stability of the Greenland and West-Antarctic ice sheets. Ice cores are unique climate archives, but their dating can be challenging. Here, the authors have realized a method for counting 81Kr atoms in 1-kg polar ice-core samples, enabling access to climate information of the past million years in deep ice.

  PublisherOA PDFDOI

• Magnesium (Mg∕Ca, <i>δ</i> ²⁶ Mg), boron (B∕Ca, <i>δ</i> ¹¹ B), and calcium (Ca ²⁺ ) geochemistry of <i>Arctica islandica</i> and <i>Crassostrea virginica</i> extrapallial fluid and shell under ocean acidification

  Biogeosciences · 2025-06-19 · 4 citations

  articleOpen access

  Abstract. The geochemistry of biogenic carbonates has long been used as proxies to record changing seawater parameters. However, the effect of ocean acidification (OA) on seawater chemistry and organism physiology could impact isotopic signatures and how elements are incorporated into the shell. In this study, we investigated the geochemistry of three reservoirs important for biomineralization – seawater, the extrapallial fluid (EPF), and the shell – in two bivalve species: Crassostrea virginica and Arctica islandica. Additionally, we examined the effects of three ocean acidification conditions (ambient: 500 ppm CO2, moderate: 900 ppm CO2, and high: 2800 ppm CO2) on the geochemistry of the same three reservoirs for C. virginica. We present data on calcification rates, EPF pH, measured elemental ratios (Mg/Ca, B/Ca), and isotopic signatures (δ26Mg, δ11B). In both species, comparisons of seawater and EPF Mg/Ca and B/Ca, Ca2+, and δ26Mg indicate that the EPF has a distinct composition that differs from seawater. Shell δ11B did not faithfully record seawater pH, and δ11B-calculated pH values were consistently higher than pH measurements of the EPF with microelectrodes, indicating that the shell δ11B may reflect a localized environment within the entire EPF reservoir. In C. virginica, EPF Mg/Ca and B/Ca, as well as absolute concentrations of Mg2+, B, and Ca2+, were all significantly affected by ocean acidification, indicating that OA affects the physiological pathways regulating or storing these ions, an observation that complicates their use as proxies. Reduction in EPF Ca2+ may represent an additional mechanism underlying reduction in calcification in C. virginica in response to seawater acidification. The complexity of dynamics of EPF chemistry suggests boron proxies in these two mollusk species are not straightforwardly related to seawater pH, but ocean acidification does lead to both a decrease in microelectrode pH and boron-isotope-based pH, potentially showing applicability of boron isotopes in recording physiological changes. Collectively, our findings show that bivalves have high physiological control over the internal calcifying fluid, which presents a challenge in using boron isotopes for reconstructing seawater pH.

  PublisherOA PDFDOI

Recent grants

• Collaborative Research: Window into the World with 40,000-year Glacial Cycles from Climate Records in Million Year-old Ice from the Allan Hills Blue Ice Area

  NSF · $576k · 2015–2020

• CAREER: What sets the CO2 thermostat? Insights from the global geochemical cycles of Ca, Mg, and K

  NSF · $819k · 2017–2022

• Collaborative Research: Snapshots of Early and Mid-Pleistocene Climate and Atmospheric Composition from the Allan Hills Blue Ice Area

  NSF · $1.1M · 2018–2024

Frequent coauthors

• Daniel P. Schrag

  44 shared

• Clara L. Blättler

  27 shared

• Anne‐Sofie C. Ahm

  22 shared

• Adam C. Maloof

  Princeton University

  19 shared

• D. Santiago Ramos

  18 shared

• Michael L. Bender

  BASF (Germany)

  17 shared

• Daniel A. Stolper

  University of California, Berkeley

  17 shared

• Francis A. Macdonald

  17 shared

Labs

• The Higgins Research LaboratoryPI

Awards & honors

• UCAR Next Generation Science Fellow (2024)