Julian Sachs

About

Julian Sachs is a chemical oceanographer who studies the mechanisms that cause climate to change on timescales ranging from decades to millennia. To do this, he and his lab develop paleoclimate records from sediment cores from throughout the world’s oceans and lakes. Molecular fossils and their hydrogen and carbon isotopic ratios are used to reconstruct past temperature, precipitation, and biological productivity. Reconstructing natural climate changes in the past provides the means to determine when the modern climate is outside the range of natural variability and improves predictions of how it will change in the future. His lab also researches the effect of ocean acidification on coral reefs through in situ carbon enrichment experiments in which the impact on reef accretion and ecosystem productivity rates are measured.

Research topics

• Geology
• Oceanography
• Geography
• Climatology
• Archaeology
• Cartography
• Meteorology

Selected publications

• Human settlement of East Polynesia earlier, incremental, and coincident with prolonged South Pacific drought

  Proceedings of the National Academy of Sciences · 2020 · 96 citations

  Significance We combine indicators from lake sediments with archaeological records that identify an earlier and incremental arrival of humans in East Polynesia than indicated by current models. We use lake sediments to reconstruct a quantitative, multiproxy hydroclimate sequences from Vanuatu, Samoa, and the Southern Cook Islands and combine these with published data to show that the timing of human migration into East Polynesia coincided with a prolonged drought. We postulate this regional drou…

  DOI

• Central eastern China hydrological changes and ENSO-like variability over the past 1800 yr

  Geology · 2021 · 65 citations

  Abstract Variations in East Asian summer monsoon (EASM) precipitation impact agriculture, water resources, electricity generation, and economic development in the densely populated region of central eastern China. However, uncertainties remain in the history and driving mechanisms of precipitation changes in this region over the past two millennia. We present an 1800 yr multiproxy reconstruction of monsoon precipitation based on hydroclimate variations inferred from Lake Nvshan sediments in the…

  DOI

• Data‐Model Comparisons of Tropical Hydroclimate Changes Over the Common Era

  Paleoceanography and Paleoclimatology · 2021 · 41 citations

  Senior authorCorresponding

  Abstract We examine the evidence for large‐scale tropical hydroclimate changes over the Common Era based on a compilation of 67 tropical hydroclimate records from 55 sites and assess the consistency between the reconstructed hydroclimate changes and those simulated by transient model simulations of the last millennium. Our synthesis of the proxy records reveals several regionally coherent patterns on centennial time scales. From 800 to 1000 CE, records from the eastern Pacific and parts of Mesoa…

  PublisherOA PDFDOI

• Assessing the interaction of oceanic and riverine processes on coastal phytoplankton dynamics in the East China Sea

  Marine Life Science & Technology · 2025-01-07 · 8 citations

  articleOpen access

  The interaction of riverine inputs and ocean current systems causes complex spatiotemporal variations in phytoplankton dynamics in marginal seas of the northwest Pacific Ocean, yet quantitative assessments of these variations and their causes remain limited. Here we evaluate phytoplankton biomass and community structure changes using lipid biomarkers, accompanying ocean circulation and nutrient variations in surface waters collected in spring and summer of 2017-2018 at 118 sites in the East Chin…

  PublisherOA PDFDOI

• Molecular and trace metal signatures of pristine and anthropogenically altered mangrove sediments

  Marine Pollution Bulletin · 2025-06-20 · 3 citations

  articleOpen access

  Mangroves contribute to long-term carbon sequestration and are considered as blue carbon ecosystems; however, they are facing increasing anthropogenic pressures, with trace metals emerging as an environmental concern. Despite their toxicological impacts, the mechanisms governing trace metal retention in mangrove sediments require further investigation, particularly their association with natural organic compounds. Here, we employed Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-…

  PublisherDOI

Recent grants

• P2C2: Late Holocene Changes in the SPCZ from Algal Lipid D/H in Lakes Across Oceania

  NSF · $424k · 2015–2018

• Reconstructing Precipitation Rates from C & H Isotopes in Mangrove Lipids

  NSF · $682k · 2017–2021

• Holocene Sea Surface Temperature (SST) and El Nino-Southern Oscillation (ENSO) Reconstructions from Peruvian Mollusks

  NSF · $99k · 2008–2010

Frequent coauthors

• Meixun Zhao

  Ocean University of China

  56 shared

• Ashley E. Maloney

  Princeton University

  34 shared

• Rienk H. Smittenberg

  Swiss Federal Institute for Forest, Snow and Landscape Research

  28 shared

• Yang Ding

  Wenzhou Medical University

  24 shared

• Daniel B. Nelson

  University of Basel

  24 shared

• S. Nemiah Ladd

  Swiss Federal Institute of Aquatic Science and Technology

  22 shared

• Mengfan Chu

  Qingdao National Laboratory for Marine Science and Technology

  22 shared

• Matthieu Carré

  Sorbonne Université

  22 shared

Similar researchers at University of Washington

• Deborah Kelleyh-60
• Richard Keilh-53
• Stephen Riserh-48