Zhonghui Liu

The University of Hong Kong | HKU · Department of Earth Sciences

The Pliocene climate, characterized by sustained global warmth and weakened Walker Circulation, might be a potential analogue of our future climate. How Asian Summer Monsoon (ASM) evolved over this period and its controlling mechanisms remain controversial, which limits our understanding of future monsoon behavior. Here, we present alkenone- and GD...

Thick Miocene lacustrine deposits have been identified across the Qaidam Basin on the northeast Tibetan Plateau, indicative of a relatively unified megalake then. How this megalake evolved at its final stage and associated controlling factors, e.g., global climate or tectonic uplift, remain largely elusive. Here we use the KC-1 well, drilled at the...

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are microbial molecular fossils ubiquitous in natural environments. The correlation between the Methylation Index of brGDGTs (the MBT′5ME paleothermometer) and temperature offers an important tool for reconstructing past terrestrial temperatures. However, factors other than temperature could...

The North Pacific Subtropical Gyre circulation redistributes heat from the Western Pacific Warm Pool towards the mid- to high-latitude North Pacific. However, the driving mechanisms of this circulation and how it changed over the Holocene remain poorly understood. Here, we present alkenone-based sea surface temperature reconstructions along the Kur...

One of the Holocene abrupt events around 4200 years ago, lasting for ∼200 years, is thought to have caused cultural disruptions, yet terrestrial climatic status right after the cold/dry event remains poorly defined and is often presumed that a generally cool condition prevailed during the Bronze Age (∼4000-2200 years ago). Here we report an alkenon...

The Miocene Climatic Optimum (MCO) from ~17 to 14 million years ago (Ma) represents an enigmatic reversal in Cenozoic cooling. A synthesis of marine paleotemperature records shows that the MCO was a local maximum in global sea surface temperature superimposed on a period from at least 19 Ma to 10 Ma, during which global temperatures were on the ord...

The subarctic Pacific Ocean, which is linked to both polar and tropical climates, is an area of high marine productivity and is sensitive to ocean-atmosphere CO2 flux. However, the mechanisms underlying the drivers of its productivity dynamics or patterns remain elusive. Using biogenic barium, opal, and terrigenous input in a sediment core for the...

Lipid compound-specific hydrogen isotopes (δD) have been widely applied in studies of biogeochemistry and paleoclimatology. δD values of lipid homologues with different chain lengths from a single analysis are often utilized together in order to make full use of the δD information. However, this approach could be potentially impacted by the large a...

Oceanic Anoxic Event 2 (OAE2) exemplifies an episode of global oceanographic and climatic changes in the mid-Cretaceous greenhouse. However, the timing and mechanism of its global initiation remain elusive. Here we report a high-resolution initial osmium isotope (¹⁸⁷Os/¹⁸⁸Osi, Osi) and δ13Corg record from an expanded OAE2 interval in southern Tibet...

Knowledge of paleolake evolution is highly important for understanding the past hydroclimate regime on the Tibetan Plateau and associated forcing mechanisms. However, the hydrological history of paleolakes on the central plateau, the core region of the plateau, remains largely inconclusive. Here we present new biomarker records from lacustrine depo...

Across the Miocene–Pliocene boundary (MPB; 5.3 million years ago, Ma), late Miocene cooling gave way to the early-to-middle Pliocene Warm Period. This transition, across which atmospheric CO 2 concentrations increased to levels similar to present, holds potential for deciphering regional climate responses in Asia—currently home to more than half of...

Coastal regions of the northern South China Sea (SCS) strongly interact with the Asian monsoon circulation (AMC). Thus, variations of sea surface temperature (SST) here are newly suggested to document AMC changes in an effective manner, but additional physical parameters of oceanic conditions, probably also in relation to the AMC system, remain poo...

The Qaidam Basin in the core area of arid Inner Asia has been considered undergoing continuous aridification over the Cenozoic. However, the Qaidam Basin is marked with expanded lacustrine sedimentation during the Oligocene, which contrasts with the fluvial or deltaic facies stratigraphically below (Eocene) and above (Miocene-present). The Oligocen...

Although the Leeuwin Current (LC) is thought to play a pivotal role in climatic and oceanic systems of the western Australian region, how the LC developed through the Pliocene-Pleistocene period remains elusive. Here we used biomarker records to reconstruct variations of temperatures and primary productivity on the northwest shelf of Australia over...

The relative proportion of mid-chain to long chain n-alkane homologues and isotopic compositions of total organic carbon (Paq and δ¹³Corg) have been proposed as potential lake-level proxies since such features mainly come from submerged aquatic plants living within an optimum range of lake water depth. With limited dataset available, the applicabil...

Orbital-scale global climatic changes during the late Quaternary are dominated by high-latitude influenced ∼100,000-year global ice-age cycles and monsoon influenced ∼23,000-year low-latitude hydroclimate variations. However, the shortage of highly-resolved land temperature records remains a limiting factor for achieving a comprehensive understandi...

Global climate shifted to markedly warmer interglacial conditions across the “mid-Brunhes transition” (MBT, ~400 ka). However, a global MBT synthesis that spans marine and terrestrial evidence remains elusive, which limits our understanding of the role of the MBT in mid-Pleistocene human evolution. We synthesize Asian precipitation reconstructions...

The first major build-up of Antarctic glaciation occurred in two consecutive stages across the Eocene–Oligocene transition (EOT): the EOT-1 cooling event at ~34.1–33.9 Ma and the Oi-1 glaciation event at ~33.8–33.6 Ma. Detailed orbital-scale terrestrial environmental responses to these events remain poorly known. Here we present magnetic and geoche...

The Cenozoic history of aridification in the Asian interior is thought to be intimately linked to uplift of the Tibetan Plateau and long-term global cooling. How fluctuating climatic conditions influenced regional moisture levels during the Cenozoic remains largely unknown. To infer moisture changes, we present oxygen isotope values of carbonates (...

Lacustrine sediments provide an excellent opportunity to study climate change beyond the instrumental period and further to elucidate its intrinsic interactions with ecosystem. However, the radiocarbon (¹⁴C)-based chronological framework of such natural archives, on which robust interpretation of geochemical proxies primarily depends, is commonly c...

The initial occurrence of desert landscape or eolian sand dunes is thought to have occurred long before the Pleistocene, and desertification was subsequently enhanced under cold, dusty glacial conditions. However, when and how the desert landscape persisted during both glacial and interglacial periods, defined as “permanent” desert here, remain elu...

Lake water salinity, an important indicator of lake hydrological conditions, is critical to deciphering terrestrial paleoclimatic and paleoenvironmental changes. The proportion of C37:4 alkenone to total C37 alkenones (%C37:4) and the relative abundance of archaeol to caldarchaeol (ACE) are promising salinity indices in lacustrine settings. Develop...

Independent inference of the Asian winter monsoon (AWM), albeit achieved at several sparse sites, has reached no consensus for its variability through the Holocene. A sediment core from the northern coast of the South China Sea (SCS) was utilized to analyze organic biomarkers at (bi‐)decadal resolution, unveiling how SCS oceanic conditions fingerpr...

Aquatic plants are major input sources of autochthonous organic matter in lake sediments, but investigations on fatty acid (FA) and n-alkane distributions in aquatic plants are currently limited, greatly hindering the applications of their isotope geochemistry in lacustrine environments. Here, the reported n-alkyl lipid distributions of aquatic pla...

Lake‐level reconstructions, related to terrestrial hydrological changes, are important for our understanding of past and future climates. Currently, however, reliable lake‐level proxies are still limited. Here we report distributions of archaeal tetraether lipids in 70 surface sediment samples collected from 55 lakes in midlatitude Asia. We have fo...

The complicity of long-term land surface temperature (LST) changes has been under investigated and less understood, hindering our understanding of the history and mechanism of terrestrial climate change. Here, we report the longest (800 thousand years) LSTs based on distributions of soil fossil bacterial glycerol dialkyl glycerol tetraethers preser...

The timing and mechanisms of the eastern equatorial Pacific (EEP) cold tongue development, a salient feature of the tropical ocean, are intensely debated on geological time scales. Here, we reconstruct cold tongue evolution over the past 8 million years by computing changes in temperature gradient between the cold tongue and eastern Pacific warm po...

The South China Sea (SCS), situated to the north of the Indo-Pacific Warm Pool (IPWP), is under the strong influence of the Asian Monsoon system. However, coastal sea surface temperature (SST) records from the SCS, which are of vital importance to exploring ocean-atmosphere-land interactions behind the Asian monsoon system, remain scarce. Here, we...

The Kuroshio Current (KC), which redistributes heat and moisture from the tropics toward mid-latitudes, considerably affects ocean–atmosphere–land interactions along its pathways. However, our knowledge about the KC strength and associated forcing, based on investigations of instrumental data and model simulations, is controversial, impeding assess...

During the Late Palaeogene between ~40 and 23 million years ago (Ma), Earth transitioned from a warm non-glaciated climate state and developed large dynamic ice sheets on Antarctica. This transition is largely inferred from the deep-sea oxygen isotope record because records from independent temperature proxies are sparse. Here we present a 25-milli...

This study reports hydrogen isotopic records from the central Chinese Loess Plateau (CLP) over the past 250 ka. After eliminating the influence of ice and local temperatures, the δDwax records extracted from two loess sites at Xifeng and Luochuan can be taken to represent arid/humid alternations in the hydrological environment in this marginal Asia...

High-resolution surface temperature records over the last two millennia are crucial to understanding the forcing and response mechanism of Earth's climate. Here we report a bidecadal-resolution sea surface temperature (SST) record based on long-chain alkenones in a gravity sediment core retrieved from the northern South China Sea. SST values varied...

This study has reconstructed the Holocene environmental history of central Tibetan Plateau, a transitional area between monsoon-dominated Asia and Westerlies-dominated Asia, to examine the interplay between the two circulation systems and effects of other potential mechanisms on the temporal variability of Holocene climatic conditions in the study...

Indian summer monsoon (ISM) variations have been linked to the orbital-scale boreal summer insolation and millennial-scale North Atlantic climates. Recent studies show the critical role of Indian Ocean sea-surface temperatures (SSTs) in affecting deglacial millennialscale monsoon oscillations. However, it is unclear whether SSTs can affect monsoon...

Oceanic Anoxic Event 2 (OAE2) was a major disturbance in global carbon cycling and transient climate disruption, triggered by a pulse of volcanic CO2. Although this well-studied perturbation to the ocean atmosphere system offers a unique opportunity to better understand abrupt climate change in response to CO2-forcing, the origin, evolution and dur...

Oceanic Anoxic Event 2 (OAE2) was a major disturbance in global carbon cycling and transient climate disruption, triggered by a pulse of volcanic CO2. Although this well-studied perturbation to the ocean–atmosphere system offers a unique opportunity to better understand abrupt climate change in response to CO2-forcing, the origin, evolution and dur...

Deepwater circulation plays a central role in global climate. Compared with the Atlantic, the Pacific deepwater circulation’s history remains unclear. The Luzon overflow, a branch of the North Pacific deep water, determines the ventilation rate of the South China Sea (SCS) basin. Sedimentary magnetic properties in the SCS reflect millennial-scale f...

On the Tibetan Plateau, applications of δD and δ18O values in paleoclimate studies tend to be complicated due to multiple processes influencing isotopic compositions in paleoclimatic archives. In this study, isotopic compositions of modern waters in the eastern Qaidam Basin on the northeastern Tibetan Plateau, and δD values of n-fatty acids (n-FA δ...

The Paleogene sedimentary records from southern China hold important clues to the impacts of the Cenozoic climate changes on low latitudes. However, although there are extensive Paleogene terrestrial archives and some contain abundant fossils in this region, few are accurately dated or have a temporal resolution adequate to decipher climate changes...

Summer temperatures on the Tibetan Plateau (TP) significantly affect stability of glaciers that provide steady water resources to nearly half of the world population. However, lack of reliable, long-term proxy records greatly impedes understanding of regional temperature sensitivity to climate forcings. Here we present a 16-ka long, alkenone-based...

Dust storms in northern China strongly affect the living and health of people there and the dusts could travel a full circle of the globe in a short time. Historically, more frequent dust storms occurred during cool periods, particularly the Little Ice Age (LIA), generally attributed to the strengthened Siberian High. However, limited by chronologi...

Long chain alkenones occur widely in lacustrine settings and their compositions are potential proxies for reconstructing terrestrial paleoclimatological and paleoenvironmental changes. However, factors influencing their occurrence, abundance, compositional pattern and unsaturation indices are not well understood. Here we investigated the alkenones...

Export production is an important component of the carbon cycle, modulating the climate system by transferring CO2 from the atmosphere to the deep-ocean via the biological pump. Here we use barite accumulation rates to reconstruct export production in the Eastern Equatorial Pacific over the past 4.3 Ma. We find that export production fluctuated con...

Solar irradiance changes are thought to play an important role in natural climate variability. How the hydrological conditions were affected by solar irradiance in westerly-controlled arid central Asia (ACA) on decadal/centennial timescales remains poorly understood because of the lack of high-quality records. Here, we integrate 1.2-year-resolution...

The extent of unsaturation in long chain alkenones (LCKs) in lakes has potential for quantitatively indicating paleotemperature in terrigenous environments. However, the traditional temperature proxies derived from marine LCKs may not be able to address the problem related to the prevalent species effect, which restricts the application of LCKs in...

The Paleogene sedimentary records from southern China hold important clues to the impacts of the Cenozoic climate changes on low-latitudes. However, although there are extensive Paleogene terrestrial archives and some contain abundant fossils in this region, few are accurately dated and have a temporal resolution adequate to decipher climate change...

Central China has experienced stronger summer monsoon during warm periods such as Marine Isotope Stages (MIS) 1 and 3, and weaker summer monsoon during cool periods such as MIS 2. The evolution history of Dajiuhu subalpine peatland in central China can help investigate how the expansion and shrinkage of peatland were associated with monsoonal stren...

The climate history over the past few centuries is important to be used to assess how regional climate responds to global forcing. Here we report three high-resolution alkenone-based sea surface temperature (SST) records over the past 4 centuries from three sediment cores collected in the Mirs Bay, northeastern Hong Kong. All three SST records cons...

Chronology is a necessary component of paleoclimatology. Radiocarbon dating plays a central role in determining the ages of geological samples younger than ca. 50 ka BP. However, there are many limitations for its application, including radiocarbon reservoir effects, which may cause incorrect chronology in many lakes. Here we demonstrate temporal c...

Precipitation in low latitudes is primarily controlled by the position of the intertropical convergence zone, which migrates from south to north seasonally. The Little Ice Age (defined as AD 1400–1850) was associated with low solar irradiance and high atmospheric aerosol concentrations as a result of several large volcanic eruptions. The mean posit...

Export production is an important component of the carbon cycle, modulating the climate system by transferring CO2 from the atmosphere to the deep ocean via the biological pump. Here we use barite accumulation rates to reconstruct export production in the eastern equatorial Pacific over the past 4.3 Ma. We find that export production fluctuated con...