R. Lawrence Edwards

University of Minnesota | UMN · Earth and Environmental Sciences

In the Northern Hemisphere, the last 16.5 kyr were characterized by abrupt temperature transitions during stadials, interstadials, and the onset of the Holocene. These changes are closely linked to large-scale variations in the extent of continental ice-sheets, greenhouse gas concentrations, and ocean circulation. The regional impact of these rapid...

The U–Th and U–Pb dating methods are widely used for radiometric dating of Pleistocene carbonates, such as speleothems and corals. The U–Th dating method has been incrementally refined over recent decades, largely through advances in mass spectrometry, and is now capable of providing accurate and precise ages for carbonates as old as 640 ka in idea...

The Quaternary Period climatic oscillations, typically those driven by Milankovitch cycles, have significantly left profound imprints in the geological records. However, the potential of terrestrial archives, particularly tufa deposits, as archives for Quaternary climate remain relatively underexplored. This study aims to contribute to filling the...

Many caves in Sicily have been shown to have a sulfuric acid or other hypogenic origin. We studied three caves (Palombara, Scrivilleri, Monello) near Syracuse (eastern Sicily), in an area that was strongly uplifted and faulted, creating multiple Pleistocene marine terraces. Mineralogy, stable isotopes and dating methods (paleomagnetism, U/Th) were...

The full understanding of climate feedbacks responsible for the amplification of deglaciations requires robust chronologies for these climate transitions, but, in the case of marine records, radiocarbon chronologies are possible only for the last glacial termination. Although the assumed relationships between the marine isotopic record and the orbi...

Marine Isotope Stage (MIS) 5c, between~106 000 and~93 000 years ago, represents an important warm period in which the current anthropogenic warming can be contextualized. Although viewed as a pronounced interstadial, its climate expression is regionally disparate, with different regions on Earth showing evidence of either cooler or warmer condition...

Deep-seafloor organisms consume oxygen, which can be measured by in situ benthic chamber experiments. Here we report such experiments at the polymetallic nodule-covered abyssal seafloor in the Pacific Ocean in which oxygen increased over two days to more than three times the background concentration, which from ex situ incubations we attribute to t...

The Younger Dryas stadial was characterised by a rapid shift towards cold-climate conditions in the North Atlantic realm during the last deglaciation. While some climate parameters including atmospheric temperature and glacier extent are widely studied, empirical constraints on permafrost temperature and snow thickness are limited. To address this,...

Identifying tropical cyclone (TC) signatures in paleoclimate records enhances our understanding of long-term TC activity trends and the climatic factors influencing TC evolution. Stalagmites are considered promising archives for recording TC activity. However, despite the western North Pacific being the most TC-active ocean basin globally, it lacks...

Quaternary climate changes are driven in part by variations in the distribution and strength of insolation due to orbital parameters. Continental climate variability is well documented for the most recent glacial-interglacial cycles, yet few records extend further back in time. Such records are critically needed to comprehensively assess the entire...

Methane is a potent greenhouse gas that enters the marine system in large quantities at seafloor methane seeps. At a newly discovered seep site off the coast of Point Dume, CA, ~ meter‐scale carbonate chimneys host microbial communities that exhibit the highest methane‐oxidizing potential recorded to date. Here, we provide a detailed assessment of...

Speleothem δ13C in monsoonal China differs from speleothem δ18O, which is widely used as a climatic proxy for several complex control reasons. Nevertheless, δ13C records have the potential to reveal the implications of hydroclimatic changes. This study reports a speleothem δ13C record from Didonghe (DDH) Cave in central China spanning 34 to 13 kyr...

Central Asia (CA) is one of the world’s most significant arid regions, which is markedly impacted by global warming. A better understanding of the dynamical processes governing its Holocene climate variability is critical for a better understanding of possible future impacts of climate change in the region. To date, most of the existing CA paleocli...

Reconstructing of past hydroclimates at regional scales during the Common Era (CE) is necessary to place the current warming in the context of natural climate variability. Here we present a composite record of oxygen isotope variations during last 2500 years based on eight stalagmites from four caves in the central Pyrenees (NE Spain) dominated by...

We present new stable oxygen and carbon isotope composite records (δ18O, δ13C) of speleothems from Sandkraal Cave 1 (SK1) on the South African south coast for the time interval between 104 and 18 ka (with a hiatus between 48 and 41 ka). Statistical comparisons using kernel-based correlation analyses and semblance analyses based on continuous wavele...

A better understanding of the relative roles of internal climate variability and external contributions, from both natural (solar, volcanic) and anthropogenic greenhouse gas forcing, is important to better project future hydrologic changes. Changes in the evaporative demand play a central role in this context, particularly in tropical areas charact...

Recent research has shown the potential of speleothem δ ¹³ C to record a range of environmental processes. Here, we report on ²³⁰ Th-dated stalagmite δ ¹³ C records for southwest Sulawesi, Indonesia, over the last 40,000 yr to investigate the relationship between tropical vegetation productivity and atmospheric methane concentrations. We demonstrat...

A spring tunnel is an ancient water installation used to artificially increase the water yield of a spring through a subterranean tunnel. We have developed a database of 216 spring tunnels documented in the central region of the Southern Levant (present‐day Israel), constructed between Iron Age II and the modern era. The study focuses on the evolut...

The last glacial period is characterized by abrupt climate oscillations, also known as Dansgaard-Oeschger (D-O) cycles. However, D-O cycles remain poorly documented in climate proxy records covering the penultimate glacial period. Here we present highly resolved and precisely dated speleothem time series from Sofular Cave in northern Türkiye to pro...

High-precision U–Th age is the key to promoting speleothem as an important archive for paleoclimate study. Notably, obtaining reliable U–Th age primarily relies on the accurate initial 230Th correction. However, correcting the U–Th age of stalagmite with the average 232Th/238U value in the crust is sometimes not enough to eliminate the effect of th...

A paradigm in paleoclimatology holds that shifts in the mean position of the Intertropical Convergence Zone were the dominant climatic mechanism controlling rainfall in the tropics during the last glacial period. We present a new paleo-rainfall reconstruction based on speleothem stable oxygen isotopes record from Colombia, which spans most of the l...

Marine Isotope Stage (MIS) 5c, between ~106,000 and ~93,000 years ago, represents an important warm period on Earth in which the current anthropogenic warming can be contextualized. Although viewed as a pronounced interstadial, its climate expression is regionally disparate, with different regions on Earth showing evidence of either cooler conditio...

A technique is developed to quantify the ultra-trace 231 Pa (35-3904 ag) concentration in seawater using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The method is a modification of the process developed by Shen et al. (Anal Chem 75(5):1075-1079, 2003. https:// doi. org/ 10. 1021/ ac026 247r) and extends it to the appli...

Radionuclides (including those of uranium and thorium) are commonly used to quantify complex geo-chemical processes in aqueous environments. The estimation of mass transport fluxes for uranium (U) and thorium (Th) isotopes is plagued, however, by uncertainties predominantly driven by the inability to determine solute-particulate partition coefficie...

These authors contributed equally to this work. Abstract: The provenance of lake particulate matter in environmentally sensitive areas is crucial to understanding regional environmental and climatic changes. This study investigated two regions in the Northeast Tibetan Plateau, China: Region I (Keluke, Tuosu, and Gahai Lakes) and Region II (Qinghai...

These authors contributed equally to this work. Abstract: The provenance of lake particulate matter in environmentally sensitive areas is crucial to understanding regional environmental and climatic changes. This study investigated two regions in the Northeast Tibetan Plateau, China: Region I (Keluke, Tuosu, and Gahai Lakes) and Region II (Qinghai...

Changes in tropical precipitation over the past millennia have usually been associated with latitudinal displacements of the Intertropical Convergence Zone (ITCZ). Recent studies provide new evidence that contraction and expansion of the tropical rain belt may also have contributed to ITCZ variability on centennial timescales. Over tropical South A...

Plain Language Summary Although El Niño‐Southern Oscillation (ENSO) is one of the most important climate phenomena globally, it is currently unknown how ENSO responds to natural variability on timescales over 100 years. Natural variability refers to periodic changes in climate due to either solar forcing, the circulation of the atmosphere and ocean...

The Younger Dryas Stadial was characterized by a rapid shift towards cold-climate conditions in the North Atlantic realm during the last deglaciation. While some climate parameters including atmospheric temperature and glacier extent are widely studied, empirical constraints on permafrost temperature and snow thickness are limited. To address this,...

A key goal of paleoclimate science is to identify the source of millennial-scale climate fluctuations. Although long-term changes in the Earth’s position relative to the Sun are the driver of climate change on timescales of ≥ 19 thousand years (ka), it is still incompletely understood what causes rapid sub-orbital changes in climate that were commo...

The investigation of cryogenic cave minerals (CCMs) has developed in recent decades to be a particularly valuable proxy for palaeo-permafrost reconstruction. Due to difficulties, however, in obtaining reliable chronologies with the so-called “fine” form of these minerals, such studies have thus far utilised the “coarse” form. In this study, we succ...

The IntCal family of radiocarbon ( ¹⁴ C) calibration curves is based on research spanning more than three decades. The IntCal group have collated the ¹⁴ C and calendar age data (mostly derived from primary publications with other types of data and meta-data) and, since 2010, made them available for other sorts of analysis through an open-access dat...

Understanding how El Niño-Southern Oscillation (ENSO) responds to natural variability is of key importance for future climate projections under a warming climate. However, there is no clear consensus on what drives ENSO’s variability on centennial timescales. Here, we find that the epikarst in southeastern Alaska is effective at filtering ENSO and...

Reconstructing of past temperatures at regional scales during the Common Era is necessary to place the current warming in the context of natural climate variability. Here we present a composite record of oxygen isotope variations during last 2500 years based on eight stalagmites from four caves in the central Pyrenees (NE Spain) dominated by temper...

New stalagmites from Qadisha Cave (Lebanon) located at 1720 m above sea level provide a high-resolution and well-dated record for north- ern Mount Lebanon. The stalagmites grew discontinuously from 9.2 to 5.7 and at 3.5 ka, and they show a tendency to move from a more negative oxygen isotope signal at ∼9.1 ka to a more positive signal at ∼5.8 ka. S...

The difficulty in constraining the large-scale Asian summer monsoon (ASM) variability in the Chinese monsoon region (CMR) during glacial Termination II lies in our limited knowledge of the western part, primarily due to sparse paleoclimate records. To get a better picture of the ASM during Termination II, we examined a precisely dated stalagmite d...

The Last Interglacial (LIG, ∼130–116 ka) was one of the warmest interglacials of the past 800 000 years and an important test bed for future climate conditions warmer than today. LIG temperature reconstructions from marine records and paleoclimate models show that middle and high northern latitudes were considerably warmer (by about 2 to 5 ∘C) comp...

Methane hydrates are widely distributed along continental margins, representing a potential source of methane to the ocean and atmosphere, possibly influencing Earth’s climate. Yet, little is known about the response of methane hydrates to global climate change, especially at the timescale of glacial-interglacial cycles. Here we present a chronolog...

Speleothem δ¹⁸O is widely used as a proxy for rainfall amount in the tropics on glacial-interglacial to interannual scales. However, uncertainties in the interpretation of this renowned proxy pose a vexing problem in tropical paleoclimatology. Here, we present paired multi-proxy geochemical measurements for stalagmites from southwest Sulawesi, Indo...

One of the key factors in obtaining precise and accurate 230Th ages of corals, especially for corals with ages less than a few thousand years, is the correction for non-radiogenic 230Th based on an initial 230Th/232Th value (230Th/232Th0). Studies that consider coral 230Th/232Th0 values in intertidal environments are limited, and it is in these env...

Estimating groundwater recharge under various climate conditions is important for predicting future freshwater availability. This is especially true for the water-limited region of the southern Great Basin, USA. To investigate the response of groundwater recharge to different climate states, we calculate the paleo recharge to a groundwater basin in...

Aim: The geography and genesis of diversity remain an enduring topic in ecology and evolution. Mediterranean Climate Ecosystems (MCEs), with their high plant diversities in winter rainfall climates, pose a challenge to popular hypotheses evoking high water availability and temperature as necessary for the evolution of high diversity. We test the hy...

Recent hydroclimate studies on the Iberian Peninsula have shown a complex regional pattern in timing and intensity of climate change spanning the Younger Dryas and the Holocene. These changes are due to multifaceted interactions between climate variability that characterizes the Atlantic Ocean region and hydroclimatic processes associated with the...

The connection between abrupt high-latitude warming during the last glacial period—Dansgaard–Oeschger (DO) events—and rapid climate changes at lower latitudes has revealed inter-hemispheric teleconnections in the ocean–atmosphere system. Links between DO events and climate variability in mid-latitude, mid-continent settings remain, however, poorly...

Changes in tropical precipitation over the past millennia have usually been associated with latitudinal displacements of the Intertropical Convergence Zone (ITCZ). Recent studies provide new evidence that contraction and expansion of the tropical rainbelt may also have contributed to ITCZ variability on centennial time scales. Over tropical South A...

Plain Language Summary Understanding the controls of the soil organic carbon (SOC) turnover on spatio‐temporal scales is of great significance to predict the soil carbon stock. The current knowledge of SOC turnover on the longer temporal scale is scarce due to a lack of accurate chronology. Here, we present Holocene speleothem U‐Th ages paired with...

Plain Language Summary As the most pronounced abrupt climate event in the Holocene, the 8.2 ka event has been studied using various geological archives worldwide, but its detailed structure in North China and its link to other climate systems remain poorly understood. Since the Beijing speleothem δ¹⁸O, a proxy of the precipitation δ¹⁸O, is sensitiv...

The investigation of cryogenic cave minerals (CCMs) has developed in recent decades to be a particularly valuable proxy for palaeo-permafrost reconstruction. Due to difficulties, however, in obtaining reliable chronologies with the so-called “fine” form of these minerals, such studies have thus far utilised the “coarse” form. In this study, we succ...

During a flood inside a cave, sands and silts are transported through the cave system and deposited as (i) a coating of this detritus on speleothem surfaces and (ii) a flood bed accumulated on the cave passages which are protected from the main water stream. After the floodwater level drops, speleothem deposition is restarted and detrital coatings...

The Marine Isotope Stage (MIS5e) is characterized by a warmer climate than that of the pre-industrial period, and serves as an analog for the Current Warm Period (CWP). However, uncertainties persist regarding its climatic stability. Here, we retrieved a stalagmite (WXB075) from Wanxiang Cave in the eastern Qinghai-Tibetan Plateau, and employed abs...

High-temporal-resolution paleomagnetic datasets are critical for understanding episodes of short-term geomagnetic field instability, such as excursions, onset of reversals, and spikes. Together with geodynamic modeling, they help in the interpretation of changes in the physical environment of the core and at the core-mantle boundary. Speleothems ar...