C. Buizert

• PhD
• Professor (Assistant) at Oregon State University

During the Last Glacial Period (LGP), Greenland experienced approximately 30 abrupt warming phases, known as Dansgaard–Oeschger (D–O) events, followed by cooling back to baseline glacial conditions. Studies of mean climate change across warming transitions reveal indistinguishable phase offsets between shifts in temperature, dust, sea salt, accumul...

Holocene temperature evolution remains poorly understood. Proxies in the early and mid‐Holocene suggest a Holocene Thermal Maximum (HTM) where temperatures exceed the pre‐industrial, whereas climate models generally simulate monotonic warming. This discrepancy may reflect proxy seasonality biases or errors in climate model internal feedbacks or dyn...

Past climate and environmental changes can be reconstructed using paleoclimate archives such as ice cores, lake and marine sediment cores, speleothems, tree rings, and corals. The dating of these natural archives is crucial for deciphering the temporal sequence of events and rates of change during past climate changes. It is also essential to provi...

The role greenhouse gases play in the evolution of Earth's climate over the last 3 million years is uncertain beyond the continuous ice core record (800,000 years). Here, we present new snapshots of carbon dioxide (CO 2 ) and methane (CH 4 ) between 3.1 and 0.4 million years ago (Ma) from shallow ice cores drilled in the Allan Hills Blue Ice Area (...

The Pleistocene Epoch is characterized by global cooling and an increase in the intensity and duration of glacial cycles. Regional surface and subsurface ocean temperature records follow distinct trends over this interval, suggesting dynamic changes in zonal and meridional heat transport and ocean circulation. Here we provide a record of global oce...

Pleistocene Ice Ages display abrupt Dansgaard–Oeschger (DO) climate oscillations that provide prime examples of Earth System tipping points—abrupt transition that may result in irreversible change. Greenland ice cores provide key records of DO climate variability, but gas-calibrated estimates of the temperature change magnitudes have been limited t...

While the processes controlling pore closure are broadly understood, the physical mechanisms driving the associated elemental fractionation remains ambiguous. Previous studies have shown that the pore closure process leads to a depletion in small-sized molecules (e.g. H2, O2, Ar, Ne, He) in ice core bubbles relative to larger-sized molecules like N...

Galactic cosmic rays (GCRs) interact with matter in the atmosphere and at the surface of the Earth to produce a range of cosmogenic nuclides. Measurements of cosmogenic nuclides produced in surface rocks have been used to study past land ice extent as well as to estimate erosion rates. Because the GCR flux reaching the Earth is modulated by magneti...

Measurements of carbon-14-containing carbon monoxide (14CO) in glacial ice are useful for studies of the past oxidative capacity of the atmosphere as well as for reconstructing the past cosmic ray flux. The 14CO abundance in glacial ice represents the combination of trapped atmospheric 14CO and in situ cosmogenic 14CO. The systematics of in situ co...

During the Last Glacial Period (LGP), Greenland experienced approximately thirty abrupt warming phases, known as Dansgaard-Oeschger (D-O) Events, followed by cooling back to baseline glacial conditions. Studies of mean climate change across warming transitions reveal indistinguishable phase-offsets between shifts in temperature, dust, sea salt, acc...

The last glacial period was punctuated by cold intervals in the North Atlantic region that culminated in extensive iceberg discharge events. These cold intervals, known as Heinrich Stadials, are associated with abrupt climate shifts worldwide. Here, we present CO 2 measurements from the West Antarctic Ice Sheet Divide ice core across Heinrich Stadi...

Past climate and environmental changes can be reconstructed using paleoclimate archives such as ice cores, lake and marine sediment cores, speleothems, tree rings and corals. The dating of these natural archives is crucial for deciphering the temporal sequence of events and rates of change during past climate changes. It is also essential to provid...

Most of the Greenland and Antarctic ice sheets are covered with firn — the transitional material between snow and glacial ice. Firn is vital for understanding ice-sheet mass balance and hydrology, and palaeoclimate. In this Review, we synthesize knowledge of firn, including its formation, observation, modelling and relevance to ice sheets. The refr...

Galactic cosmic rays (GCRs) interact with matter in the atmosphere and at the surface of the Earth to produce a range of cosmogenic nuclides. Measurements of cosmogenic nuclides produced in surface rocks have been used to study past land ice extent as well as to estimate erosion rates. Because the GCR flux reaching the Earth is modulated by magneti...

Processes controlling pore closure are broadly understood yet defining the physical mechanisms controlling associated elemental fractionation remains ambiguous. Previous studies have shown that the pore closure process leads to a decrease in concentration of small-size molecules (e.g., H2, O2, Ar, Ne, He) in the trapped bubbles. Ice core δ(O2/N2) r...

The SUMup database is a compilation of surface mass balance (SMB), subsurface temperature and density measurements from the Greenland and Antarctic ice sheets available at https://www.doi.org/10.18739/A2M61BR5M (Vandecrux et al., 2023). This 2023 release contains 4 490 442 data points: 1 778 540 SMB measurements, 2 706 413 density measurements and...

Atmospheric methane is second only to CO2 in terms of anthropogenic greenhouse warming and is a key player in global atmospheric chemistry. Atmospheric methane has been increasing at a record rate during the past few years and the causes of this alarming acceleration are uncertain, with changes in natural and anthropogenic sources as well as in the...

Constraining the causes of past atmospheric methane variability is important for understanding links between methane and climate. Abrupt methane changes during the last deglaciation have been intensely studied for this purpose, but the relative importance of high-latitude and tropical sources remains poorly constrained. The methane interpolar conce...

The total air content (TAC) of polar ice cores has long been considered a potential proxy for past ice sheet elevation. Recent work, however, has shown that a variety of other factors also influence this parameter. In this paper we present a high-resolution TAC record from the South Pole ice core (SPC14) covering the last 54 000 years and discuss t...

Measurements of carbon-14-containing carbon monoxide (14CO) in glacial ice are useful for studies of the past oxidative capacity of the atmosphere as well as for reconstructing the past cosmic ray flux. 14CO abundance in glacial ice represents the combination of trapped atmospheric 14CO and in situ cosmogenic 14CO. The systematics of in situ cosmog...

We present a database of observational constraints on past Antarctic Ice Sheet changes during the last glacial cycle intended to consolidate the observations that represent our understanding of past Antarctic changes and for state-space estimation and paleo-model calibrations. The database is a major expansion of the initial work of Briggs and Tara...

Temporal changes in the magnitude and geographic distribution of different sources of nitrous oxide (N2O) are not well constrained. To better understand the dynamics of N2O in the atmosphere over the last century, we have reconstructed the mole fraction, δ¹⁵Nbulk, δ¹⁸O, and δ¹⁵NSP values of N2O from ice cores, firn air archives, and modern atmosphe...

The total air content (TAC) of polar ice cores has long been considered a potential proxy for past ice sheet elevation. Recent work, however, has shown that a variety of other factors also influence this parameter. In this paper we present a high-resolution TAC record from the South Pole (SPC14) ice core covering the last 54,000 years and discuss t...

During the last ice age, the Laurentide Ice Sheet exhibited extreme iceberg discharge events that are recorded in North Atlantic sediments¹. These Heinrich events have far-reaching climate impacts, including widespread disruptions to hydrological and biogeochemical cycles2–4. They occurred during Heinrich stadials—cold periods with strongly weakene...

Here we present a newly developed ice core gas-phase proxy that directly samples a component of the large-scale atmospheric circulation: synoptic-scale pressure variability. Surface pressure changes weakly disrupt gravitational isotopic settling in the firn layer, which is recorded in krypton-86 excess (86Krxs). The 86Krxs may therefore reflect the...

Reconstructing the history of polar temperature from ice core water isotope ( δ ¹⁸ O) calibration has remained a challenge in paleoclimate research, because of our incomplete understanding of various temperature– δ ¹⁸ O relationships. This paper resolves this classical problem in a new framework called the unified slope equations (USE), which illus...

Cosmic rays entering the Earth's atmosphere produce showers of secondary particles such as protons, neutrons, and muons. The interaction of these particles with oxygen-16 (16O) in minerals such as ice and quartz can produce carbon-14 (14C). In glacial ice, 14C is also incorporated through trapping of 14C-containing atmospheric gases (14CO2, 14CO, a...

Constraining the causes of past atmospheric methane variability is important for understanding links between methane and climate. Abrupt methane changes during the last deglaciation have been intensely studied for this purpose, but the relative importance of high-latitude and tropical sources remains poorly constrained. The methane interpolar conce...

We present a database of observational constraints on past Antarctic ice sheet changes during the last glacial cycle intended to consolidate the observations that represent our understanding of past Antarctic changes, for state-space estimation, and paleo-model calibrations. The database is a major expansion of the initial work of Briggs and Taraso...

Precise ice-core chronologies are essential for identifying the timing and duration of polar climatic changes as well as their phasing with the changes in other parts of the globe. However, existing ice-core chronologies beyond the last 60 kyr show relatively large disagreements with each other and with U-Th chronologies of speleothems. Here, we co...

Here we present a newly developed ice core gas-phase proxy that directly samples a component of the large-scale atmospheric circulation: synoptic-scale pressure variability. Surface pressure variability weakly disrupts gravitational isotopic settling in the firn layer, which is recorded in krypton-86 excess (86Krxs). We validate 86Krxs using late H...

In blue-ice areas (BIAs), deep ice is directly exposed at the surface, allowing for the cost-effective collection of large-sized old-ice samples. However, chronostratigraphic studies on blue-ice areas are challenging owing to fold and fault structures. Here, we report on a surface transect of ice with an undisturbed horizontal stratigraphy from the...

Gas isotope thermometry using the isotopes of molecular nitrogen and argon has been used extensively to reconstruct past surface temperature change from Greenland ice cores. The gas isotope ratios δ15N and δ40Ar in the ice core are each set by the amount of gravitational and thermal fractionation in the firn. The gravitational component of fraction...

Cosmic rays entering the Earth’s atmosphere produce showers of secondary particles such as neutrons and muons. The interaction of these neutrons and muons with oxygen-16 (16O) in minerals such as ice and quartz can produce carbon-14 (14C). Analyses of in situ produced cosmogenic 14C in quartz are commonly used to investigate the Earth’s landscape e...

The limited number of surface mass balance (SMB) observations in the Antarctic inland hampers estimates of ice‐sheet contribution to global sea level and locations with million‐year‐old ice. We present finely resolved SMB over the past three centuries in a low‐accumulation region with significant depth hoar formation on Dome Fuji derived from ∼1,10...

Submission to 15th International Conference on Accelerator Mass Spectrometry 15-19 November 2021.

Deglaciations are characterized by relatively fast and near-synchronous changes in ice sheet volume, ocean temperature, and atmospheric greenhouse gas concentrations, but glacial inception occurs more gradually. Understanding the evolution of ice sheet, ocean, and atmosphere conditions from interglacial to glacial maximum provides insight into the...

Blue ice areas (BIAs) allow for the collection of large-sized old ice samples in a cost-effective way because deep ice outcrops and make old ice samples available close to the surface. However, most chronostratigraphy studies on blue ice are complicated due to fold and fault structures. Here, we report a simple stratigraphy of ice from the Larsen B...

Presentation at AGU Fall Meeting, 13-17 December 2021.

Data from the South Pole ice core (SPC14) are used to constrain climate conditions and ice‐flow‐induced layer thinning for the last 54,000 years. Empirical constraints are obtained from the SPC14 ice and gas timescales, used to calculate annual‐layer thickness and the gas‐ice age difference (Δage), and from high‐resolution measurements of water iso...

Antarctic paleotemperatures It has been widely thought that East Antarctica was ∼9°C cooler during the Last Glacial Maximum, close to the ∼10°C difference between then and now determined independently for West Antarctica. Buizert et al. used borehole thermometry, firn density reconstructions, and climate modeling to show that the temperature in Eas...

Abrupt climate changes during the last deglaciation have been well preserved in proxy records across the globe. However, one long-standing puzzle is the apparent absence of the onset of the Heinrich Stadial 1 (HS1) cold event around 18 ka in Greenland ice core oxygen isotope  18 O records, inconsistent with other proxies. Here, combining proxy rec...

Deglaciations are characterized by relatively fast and near-synchronous changes in ice sheet volume, ocean temperature, and atmospheric greenhouse gas concentrations, but glacial inceptions occur more gradually. Understanding the evolution of ice sheet, ocean, and atmospheric conditions from interglacial to glacial maximum provides important insigh...

A new ice core drilled at the South Pole provides a 54 000-year paleoenvironmental record including the composition of the past atmosphere. This paper describes the SP19 chronology for the South Pole atmospheric gas record and complements a previous paper (Winski et al., 2019) describing the SP19 ice chronology. The gas chronology is based on a dis...

In 2013 an ice core was recovered from Roosevelt Island, an ice dome between two submarine troughs carved by paleo-ice-streams in the Ross Sea, Antarctica. The ice core is part of the Roosevelt Island Climate Evolution (RICE) project and provides new information about the past configuration of the West Antarctic Ice Sheet (WAIS) and its retreat dur...

The last glacial period is characterized by a number of millennial climate events that have been identified in both Greenland and Antarctic ice cores and that are abrupt in Greenland climate records. The mechanisms governing this climate variability remain a puzzle that requires a precise synchronization of ice cores from the two hemispheres to be...

Rapid warming is profoundly affecting Arctic ecosystems, accelerating Greenland Ice Sheet (GrIS) melting, reducing sea ice cover, raising sea level and endangering coastal societies and infrastructure. However, large uncertainties remain about the projected rate and magnitude of Arctic cryosphere and ecosystem change in the coming decades under pla...

Rapid warming is profoundly affecting Arctic ecosystems, accelerating Greenland Ice Sheet (GrIS) melting, reducing sea ice cover, raising sea level and endangering coastal societies and infrastructure. However, large uncertainties remain about the projected rate and magnitude of Arctic cryosphere and ecosystem change in the coming decades under pla...

A new ice core drilled at the South Pole provides a 54 000-year paleoenvironmental record including the composition of the past atmosphere. This paper describes the SP19 chronology for the South Pole atmospheric gas record and complements a previous paper (Winski et al., 2019) describing the SP19 ice chronology. The gas chronology is based on a dis...

Abstract. The last glacial period is characterized by a number of abrupt climate events that have been identified in both Greenland and Antarctic ice cores. The mechanisms governing this climate variability remain a puzzle that requires a precise synchronization of ice cores from the two Hemispheres to be resolved. Previously, Greenland and Antarct...

The South Pole Ice Core (SPICEcore) was drilled in 2014–2016 to provide a detailed multi-proxy archive of paleoclimate conditions in East Antarctica during the Holocene and late Pleistocene. Interpretation of these records requires an accurate depth–age relationship. Here, we present the SPICEcore (SP19) timescale for the age of the ice of SPICEcor...

Firn air provides plenty of old air from the near past, and can therefore be useful for understanding human impact on the recent history of the atmospheric composition. Most of the existing firn air records cover only the last several decades (typically 40 to 55 years) and are insufficient to understand the early part of anthropogenic impacts on th...

We reconstruct atmospheric abundances of the potent greenhouse gas c-C4F8 (perfluorocyclobutane, perfluorocarbon PFC-318) from measurements of in situ, archived, firn, and aircraft air samples with precisions of ∼1 %–2 % reported on the SIO-14 gravimetric calibration scale. Combined with inverse methods, we found near-zero atmospheric abundances fr...

38 The South Pole Ice Core (SPICEcore) was drilled in 2014-2016 to provide a 39 detailed multi-proxy archive of paleoclimate conditions in East Antarctica during the 40 Holocene and late Pleistocene. Interpretation of these records requires an accurate depth-41 age relationship. Here, we present the SP19 timescale for the age of the ice of SPICEcor...

The last deglaciation, which occurred from 18 000 to 11 000 years ago, is the most recent large natural climatic variation of global extent. With accurately dated paleoclimate records, we can investigate the timings of related variables in the climate system during this major transition. Here, we use an accurate relative chronology to compare tempe...

We reconstruct atmospheric abundances of the potent greenhouse gas c-C4F8 (perfluorocyclobutane, perfluorocarbon PFC-318) from measurements of in situ, archived, firn, and aircraft air samples with precisions of ~ 1–2 % reported on the SIO-14 gravimetric calibration scale. Combined with inverse methods, we found near zero atmospheric abundances fro...

We present a 2700-year annually resolved chronology and snow accumulation history for the Roosevelt Island Climate Evolution (RICE) ice core, Ross Ice Shelf, West Antarctica. The core adds information on past accumulation changes in an otherwise poorly constrained sector of Antarctica. The timescale was constructed by identifying annual cycles in h...

Firn air provides plenty of old air from the near past, and can therefore be useful for understanding human impact on the recent history of the atmospheric composition. Most of the existing firn air records cover only the last several decades (typically 40 to 55 years) and are insufficient to understand the early part of anthropogenic impacts on at...

The mid-latitude westerly winds of the Southern Hemisphere play a central role in the global climate system via Southern Ocean upwelling1, carbon exchange with the deep ocean2, Agulhas leakage (transport of Indian Ocean waters into the Atlantic)3 and possibly Antarctic ice-sheet stability4. Meridional shifts of the Southern Hemisphere westerly wind...

In 2013, an ice core was recovered from Roosevelt Island in the Ross Sea, Antarctica, as part of the Roosevelt Island Climate Evolution (RICE) project. Roosevelt Island is located between two submarine troughs carved by paleo-ice-streams. The RICE ice core provides new important information about the past configuration of the West Antarctic Ice She...

A growing network of ice cores reveals the past 800,000 years of Antarctic climate and atmospheric composition. The data show tight links among greenhouse gases, aerosols and global climate on many timescales, demonstrate connections between Antarctica and distant locations, and reveal the extraordinary differences between the composition of our pr...

Ancient air trapped in ice core bubbles has been paramount to developing our understanding of past climate and atmospheric composition. Before air bubbles become isolated in ice, the atmospheric signal is altered in the firn column by transport processes such as advection and diffusion. However, the influence of low-permeability layers and barometr...

The sensitivity of the Northeast Greenland Ice Stream (NEGIS) to prolonged warm periods is largely unknown and geological records documenting such long-term changes are needed to place current observations in perspective. Here we use cosmogenic surface exposure and radiocarbon ages to determine the magnitude of NEGIS margin fluctuations over the la...

The last deglaciation, which occurred from 18,000 to 11,000 years ago, is the most recent large natural climatic variation of global extent. With accurately dated paleoclimate records, we can investigate the timings of related variables in the climate system during this major transition. Here, we use an accurate relative chronology to compare regio...

High-resolution, well-dated climate archives provide an opportunity to investigate the dynamic interactions of climate patterns relevant for future projections. Here, we present data from a new, annually dated ice core record from the eastern Ross Sea, named the Roosevelt Island Climate Evolution (RICE) ice core. Comparison of this record with clim...

The sensitivity of the Greenland Ice Sheet to climate forcing is of key importance in assessing its contribution to past and future sea-level rise. Surface mass loss occurs during summer, and accounting for temperature seasonality is critical in simulating ice-sheet evolution and in interpreting glacial landforms and chronologies. Ice-core records...

Ancient air trapped in ice core bubbles has been paramount to developing our understanding of past climate and atmospheric composition. Before air bubbles become isolated in ice, the atmospheric signal is altered in the firn column by transport processes such as advection and diffusion. However, the influence of impermeable layers and barometric pu...

Marine sediments, speleothems, paleo-lake elevations, and ice core methane and δ18O of O2 (δ18Oatm) records provide ample evidence for repeated abrupt meridional shifts in tropical rainfall belts throughout the last glacial cycle. To improve understanding of the impact of abrupt events on the global terrestrial biosphere, we present composite recor...

Significance Cold and dry glacial-state climate conditions persisted in the Southern Hemisphere until approximately 17.7 ka, when paleoclimate records show a largely unexplained sharp, nearly synchronous acceleration in deglaciation. Detailed measurements in Antarctic ice cores document exactly at that time a unique, ∼192-y series of massive haloge...

We present a 2700-year annually resolved timescale for the Roosevelt Island Climate Evolution (RICE) ice core, and reconstruct a past snow accumulation history for the coastal sector of the Ross Ice Shelf in West Antarctica. The timescale was constructed by identifying annual layers in multiple ice-core impurity records, employing both manual and a...

Methane (CH4) is a powerful greenhouse gas and plays a key part in global atmospheric chemistry. Natural geological emissions (fossil methane vented naturally from marine and terrestrial seeps and mud volcanoes) are thought to contribute around 52 teragrams of methane per year to the global methane source, about 10 per cent of the total, but both b...