About

Tim Herbert is a professor in the Department of Earth, Environmental & Planetary Sciences at Brown University. His research focuses on understanding how the Earth's climatic system, particularly the ocean, adjusts itself to perturbations on various timescales. He specializes in reconstructing past ocean surface temperatures and ecosystems, linking these to global climate changes and greenhouse gas control. His work involves fieldwork, sea-going expeditions, and laboratory analysis using organic biomarkers and stable isotopes in carbonate microfossils. Professor Herbert's research emphasizes the climate of the Neogene period, which saw significant events such as the near-complete deglaciation of Antarctica from approximately 17.5 to 14 million years ago, and the subsequent cooling and aridification leading into the ice ages of the past 2.7 million years. He has contributed to studies challenging previous ideas about ancient climate conditions, such as the drying of northern Africa around 3 million years ago, and has explored the relationship between carbon dioxide levels and the rhythm of ice ages. His work also includes analyzing sea sediments to uncover clues about Earth's climate history. In addition to his research, Professor Herbert has been recognized with awards, including the 2023 Salomon Award for developing proof of concept data related to the long-term stability of the Antarctic ice cap. He has participated in international expeditions, such as the drilling project off the coast of Portugal aimed at learning about Earth's past climate to inform future climate resilience strategies.

Research topics

• Climatology
• Oceanography
• Geology
• Biology
• Paleontology
• Ecology

Selected publications

• Onset of millennial climate variability with the intensification of Northern Hemisphere glaciation

  Science · 2026-02-19 · 2 citations

  article

  The Quaternary Period (the past 2.58 million years) was characterized by the waxing and waning of large ice sheets in the Northern Hemisphere. Using sediment sequences from the Iberian Margin, we have demonstrated that expansion of Northern Hemisphere ice sheets around 2.7 million years ago was accompanied by the emergence of millennial climate variability (MCV) during glacial periods. The onset of MCV at ~2.7 million years ago was heralded by isolated precursor events, followed by multiple millennial climate oscillations at ~2.5 million years ago. These events coincided with deposition of ice-rafted detritus in the North Atlantic, suggesting a role for marine-terminating ice sheets. Once established, MCV became an intrinsic feature of glacial climates of the Quaternary. Our findings underscore the profound impact Northern Hemisphere glaciation had on climate variability across multiple timescales.

  PublisherDOI

• East Antarctic ocean-ice sheet interactions during Miocene warmth

  2026-03-13

  articleOpen accessSenior authorCorresponding

  Regions of Antarctica were most recently ice-free during the Miocene Climatic Optimum (MCO, ~17-14 Ma). During this warm interval, the East Antarctic Ice Sheet (EAIS) exhibited highly dynamic behavior and episodic wide-scale retreat associated with global sea level rise. During the subsequent Middle Miocene Climate Transition (MMCT), the EAIS expanded and stabilized with contemporaneous global cooling. However, little is directly known about drivers of EAIS behavior during the Miocene due to a lack of continuous, high-resolution climate records near Antarctica. Here, we present multi-proxy (Uk’37 and TEX86) biomarker records of sea surface temperatures (SSTs) from Ocean Drilling Program (ODP) Site 1165 in the polar Southern Ocean to constrain ocean-ice sheet interactions in the Prydz Bay region of East Antarctica throughout the Miocene. Our records span 5 to 19 Ma, with orbital-resolution data (5 kyr) during the MMCT from 13.2 to 15.1 Ma. We find peak SSTs during the MCO up to 18°C warmer than modern as well as polar-amplified cooling synchronous with the establishment of permanent Antarctic glaciation and broader global cooling during the MMCT (13.8 Ma) and Late Miocene (6-8 Ma). Comparison of our high-resolution SST record and ice rafted debris at the same site shows that ice rafting disappeared when SSTs warmed above 12°C, demonstrating the vulnerability of the marine ice margin to ocean warming. However, comparison with global benthic oxygen isotope records indicates that terrestrial-based ice volume exhibited threshold behavior as transient cooling during the MMCT crossed a tipping point for terrestrial ice sheet growth and stabilization, which subsequent warming was not sufficient to reverse. These results constrain the EAIS response to elevated greenhouse gas concentrations during the past global warmth of the Miocene, with implications for potential future long-term behavior of Earth’s largest ice sheet.

  PublisherDOI

• Perspectives of IODP3 Expedition 506S SIGNALS - Stratigraphic InteGration of North Atlantic Legacy Sites

  2026-03-13

  articleOpen accessCorresponding

  SPARC (Scientific Projects using Ocean Drilling Archives) is an IODP3 programme to utilize legacy cores by large-scale research groups. Three projects (Exp. 504S, Exp. 505S, Exp. 506S) were launched in the first year, with a start date in summer or fall and will last for three years.The North Atlantic plays a crucial role in regulating global climate due to its proximity to major ice sheets and sensitivity to changes in the Atlantic Meridional Overturning Circulation (AMOC). Over millennial and orbital timescales, the region has experienced abrupt climate shifts with significant global implications. The Exp. 506S SIGNALS (Stratigraphic InteGration of North Atlantic Legacy Sites) project aims to synthesize and integrate legacy records into a coherent, four-dimensional stratigraphic framework to provide a regional reconstruction of past climate variability on millennial to orbital timescales since the late Miocene.SIGNALS will enhance stratigraphic correlation, refine age models, and synchronize proxy datasets for multiple legacy sites across the North Atlantic spanning a wide range of climatic and bathymetric gradients. The project will capitalize on advanced methods, including machine learning and signal correlation algorithms, to rapidly produce high-resolution data by automated processing of core images, point counting, and precise stratigraphic correlation.SIGNALS will address methodological issues associated with estimating uncertainty in stratigraphic correlations and the limits of temporal resolution at each site given varying sedimentation rates, bioturbation, and sampling frequency. Furthermore, we will develop process models to understand how orbitally-driven climatic changes are expressed as cycles in the stratigraphic record of each site. By analyzing high-resolution geochemical and sedimentological proxies in a robust stratigraphic framework, the project seeks to reconstruct climate evolution and ocean circulation changes across the North Atlantic since the late Miocene. The project will focus on major climatic transitions and provide robust regional paleoclimate data for numerical modeling and assimilation studies. Beyond research advancements, SIGNALS will also foster collaboration by developing user-friendly computational tools, training early-career researchers, and making data publicly accessible through open repositories.Although the exact implementation plan will not be decided until the science team has been selected, we will present objectives and general plans of Exp. 506S SIGNALS as one of the first SPARC projects.

  PublisherDOI

• Comment on egusphere-2025-5436

  2026-01-05

  peer-reviewOpen access

  <strong class="journal-contentHeaderColor">Abstract.</strong> The Pliocene epoch, 5.33&ndash;2.58 Ma, is considered a key analogue for near-future climate scenarios, as it had atmospheric CO₂ levels (&gt;400 ppm) comparable to today and similar continental positioning. Understanding Pliocene climate evolution is also critical to establishing the conditions that enabled large ice sheets to form in the Arctic region during the intensification of Northern Hemisphere glaciation (iNHG) around 2.7 Ma. The causes of iNHG remain unclear, with hypotheses ranging from tectonic changes to CO₂ reductions. Based on anomalous, pre-iNGH cooling signals recorded in a sea surface temperature (SST) record from Ocean Drilling Program (ODP) Site 1090, located in the southeastern Atlantic Ocean, studies have posited that early cooling of the already-glaciated Southern Hemisphere could have driven Earth&rsquo;s climatic descent into the Pleistocene. Here, we provide an orbitally resolved alkenone-based SST record of ODP Site 1090 spanning the time interval ~4.3&ndash;2.6 Ma with improved laboratory protocols that significantly revises conclusions based on prior work. Our revised record of SSTs from ODP 1090 shows similar cooling trends to those found of equatorial and high latitude Northern Hemisphere sites, suggesting that a global forcing, such as a reduction in atmospheric CO₂, prompted iNHG, as opposed to an early cooling of the Southern Hemisphere.

  PublisherDOI

• Plio‐Pleistocene Evolution of the Benguela and Agulhas Currents

  Paleoceanography and Paleoclimatology · 2026-01-01

  articleOpen accessSenior author

  Abstract Reconstructing the evolution of the Benguela and Agulhas currents throughout the Plio‐Pleistocene and understanding the controls on productivity and sea surface temperature at their confluence is of wide interest. This period of Earth's history is marked by a multi‐million‐year global cooling trend that may be reflected in the local climates influenced by the two systems. We present alkenone based sea surface temperature (SST) and biological productivity (C 37 total/MAR) records at ODP Sites 1085 and 1087 located at the southern end of the modern Benguela Upwelling System (BUS) and under the influence of the Agulhas Current, respectively. At both sites we find SST evolution mirrors the evolution of other upwelling systems across the globe, while productivity was more susceptible to local precession‐driven climate change. The SST gradient between the two sites tracks the intensity and location of the currents and shows that the Agulhas leakage was present consistently at Site 1087 for the past 3.5 Ma. The gradient oscillates at orbital time scales with its strongest peaks coinciding with the glacial cycles. Through a comparison to other Benguela alkenone records we propose that prior to the Mid‐Pleistocene Transition (MPT) the BUS extended further south and slightly muted the presence of Agulhas leakage at Site 1087. Our results suggest that post‐MPT the southern boundary of the BUS shifted northward resulting in the increased influence of the Agulhas at Site 1087 and strengthened upwelling in the northern and central cells of the BUS.

  PublisherOA PDFDOI

• Onset of millennial climate variability with the intensification of Northern Hemisphere glaciation.

  Open MIND · 2026-02-05

  article

  The Quaternary Period (the past 2.58 million years) was characterized by the waxing and waning of large ice sheets in the Northern Hemisphere. Using sediment sequences from the Iberian Margin, we have demonstrated that expansion of Northern Hemisphere ice sheets around 2.7 million years ago was accompanied by the emergence of millennial climate variability (MCV) during glacial periods. The onset of MCV at ~2.7 million years ago was heralded by isolated precursor events, followed by multiple millennial climate oscillations at ~2.5 million years ago. These events coincided with deposition of ice-rafted detritus in the North Atlantic, suggesting a role for marine-terminating ice sheets. Once established, MCV became an intrinsic feature of glacial climates of the Quaternary. Our findings underscore the profound impact Northern Hemisphere glaciation had on climate variability across multiple timescales.

  DOI

• Coupled Southern Ocean temperatures and East Antarctic hydroclimate during Miocene global warmth

  2026-03-14

  articleOpen accessSenior authorCorresponding

  East Antarctica experienced a dramatic transformation in hydroclimate during the Miocene, from warm and wet conditions during the Miocene Climatic Optimum (MCO, ~14-17 Ma) to the establishment of polar desert conditions with cooling and ice sheet expansion during the Middle Miocene Climate Transition (MMCT, ~13.8 Ma) and late Miocene cooling interval (~6-8 Ma). During Miocene warmth, retreat of Antarctic ice sheets allowed for the rise of vascular plant ecosystems on Antarctica, which preserved information on terrestrial hydroclimate through their epicuticular waxes. Here, we investigate molecular biomarkers of plant waxes from East Antarctica preserved in the polar Southern Ocean at Ocean Drilling Program Site 1165. We quantify the isotopic composition of long-chain n-alkanoic acids, providing a record between 5 and 19 Ma. In addition, we present high-resolution (5 kyr) data between 13.2 and 15.1 Ma which span the expansion of the East Antarctic Ice Sheet during the MMCT.Comparison of plant wax isotopes (δD) with Uk’37, a sea surface temperature (SST) proxy, that we measured in the same samples constrains interactions between polar Southern Ocean temperatures and East Antarctic terrestrial hydroclimate throughout the Miocene. Our records reveal a timescale-dependent relationship between SSTs and plant wax δD, with opposing isotopic responses to temperature forcing on orbital versus longer timescales. Our results demonstrate a complex response of Antarctic precipitation isotopes during the Miocene, with plant wax δD not only reflecting temperature changes, but also changes in vapor transport to Antarctica, aridity, and/or ecology. We conclude that our plant wax constraints on Antarctic precipitation isotopes have broader implications for the past isotopic composition of the East Antarctic Ice Sheet and the resulting deconvolution of global benthic δ18O into temperature and ice volume components during the Miocene.

  PublisherDOI

• Comment on egusphere-2025-5181

  2026-02-13

  peer-reviewOpen access

  <strong class="journal-contentHeaderColor">Abstract.</strong> Sea Surface Temperature reconstructions derived from alkenone biomarker (SST-alk) reveal a cooling trend in the North Atlantic during the late Holocene (the last 5,000 years), contrary to the warming simulated by transient climate models driven by 20 ppm increase in greenhouse gas concentrations. It has been suggested that the apparent cooling in paleo-records may reflect the evolution of summer temperatures, a seasonal signal biased by the preferential growth of haptophyte algae during warm months. Here, we investigate the spatial pattern of SST-alk changes and show that late Holocene cooling is characterized by an increased zonal SST gradient in the mid-latitude North Atlantic, with greater cooling in the west than in the east. Multiple proxies indicate that this increase in zonal asymmetry is associated with reorganizations of the inter-gyre ocean circulation. We find that transient simulations, such as TraCE-21k, do not reproduce the zonally asymmetric cooling and the inferred changes in inter-gyre circulation from the mid- to late Holocene. This misrepresentation of spatial and temporal variability likely explains the data-model discrepancy in the mid-latitude North Atlantic.

  PublisherDOI

• Millennial-timescale East Antarctic Ice Sheet variability and recurrent seafloor oxidation pulses during the Miocene Climatic Optimum at Prydz Bay

  2026-03-14

  articleOpen accessCorresponding

  The Amery Ice Shelf, the third largest ice shelf at the head of Prydz Bay, and one of the four regions where Antarctic Deep Waters form, is reported as one of the most stable portions of the East Antarctic Ice Sheet (EAIS). Yet, its response to future warming remains uncertain. The Miocene Climatic Optimum (MCO, ~17–15 million years ago) is the warmest period of the past 23 million years, with global temperatures 3–8°C above modern and pCO2 of 400–600 ppm, similar to end-century projections. It therefore provides a valuable opportunity to investigate EAIS stability under warm conditions. Here, we present a combined lipid biomarker, palynology and XRF record from ODP Site 1165, offshore Prydz Bay, spanning ~16.3-16 Ma at an unprecedented millennial-scale resolution, crucial for understanding the near-future EAIS conditions in a warmer world. Interestingly, the record shows recurrent pulse-like intense organic matter oxidation events associated with elevated proportions of reworked and oxidation-resistant in situ dinoflagellate cysts as well as ice-rafted debris (IRD). IRD presence in this record was previously interpreted as evidence for deglaciation. However, deglaciation, meltwater and subsequent stratification are somewhat in contrast with seafloor oxidation. Oxidation events at the seafloor may rather be linked to oxygen-rich deepwater associated with EAIS and sea ice dynamics at location, or other processes we are investigating. Excluding the interval where organic matter oxidation is recorded, the remaining record indicates relatively stable seawater conditions. Specifically regarding sea water temperature (SST) based on glycerol dialkyl glycerol tetraethers (GDGTs)-based SST proxy (TEX86) and alkenone-based SST proxy both suggest SSTs around 9-16°C, although hydroxylated-GDGTs suggest much lower SSTs around 4-9°C. Furthermore, the occurrence of plant-derived fatty acids and pollen-spore assemblages indicate a sustained woody-tundra vegetation and an intensified hydrological cycle on the hinterland than modern throughout the record.

  PublisherDOI

• Supplementary material to "Late Holocene cooling and increased zonal asymmetry in the mid-latitude North Atlantic"

  2025-10-29

  articleOpen access
  PublisherDOI

Recent grants

• Collaborative Research: High Latitude Temperature and Biological Responses to Plio-Pleistocene Global Change

  NSF · $299k · 2006–2011

• Collaborative Research: High resolution paleoceanography in the heart of the Equatorial Pacific Cold Tongue

  NSF · $343k · 2010–2013

• Collaborative Research:Decadal to orbital links between climate, productivity, and denitrification on the Peru Margin; Do models of persistent EL Ni±o or La Nina conditions apply?

  NSF · $208k · 2003–2008

• New, GK-12 Physical Processes in the Environment

  NSF · $3.0M · 2007–2013

• Collaborative Research: Did the SE Pacific Gyre become a Hot Spot for N2 Fixation during Dusty Glacial Conditions?

  NSF · $178k · 2016–2022

Frequent coauthors

• K. T. Lawrence

  Providence College

  134 shared

• Zhonghui Liu

  University of Hong Kong

  79 shared

• Rocio P Caballero-Gill

  78 shared

• Alexandrina Tzanova

  54 shared

• Alexey V. Fedorov

  Yale University

  51 shared

• Jonathan P LaRiviere

  University of California, Santa Cruz

  51 shared

• L. C. Peterson

  Union of Concerned Scientists

  50 shared

• Chris Brierley

  49 shared

Labs

• Deep Geosciences (DEEPS) at Brown UniversityPI

Education

• Ph,D., Geological Sciences

  Princeton University

  1987

Awards & honors

• 2023 Salomon Award