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Introduction
Additional affiliations
June 2014 - August 2014
August 2014 - July 2015
October 2007 - June 2008
Publications
Publications (338)
We examine results from two transient modeling experiments that simulate the Last Interglacial period (LIG) using the state-of-the-art Community Earth System Model (CESM2), with a focus on climate and ocean changes relevant to the possible collapse of the Antarctic ice sheet. The experiments simulate the early millennia of the LIG warm period using...
The persistence and size of the Greenland Ice Sheet (GrIS) through the Pleistocene is uncertain. This is important because reconstructing changes in the GrIS determines its contribution to sea level rise during prior warm climate periods and informs future projections. To understand better the history of Greenland’s ice, we analyzed glacial till co...
We examine results from two transient modelling experiments that simulate the Last Interglacial period (LIG) using the state-of-the-art Community Earth System Model (CESM2), with a focus on climate and ocean changes relevant to the possible collapse of the Antarctic ice sheet. The experiments simulate the early millennia of the LIG warm period usin...
Geology and bed topography influence how ice sheets respond to climate change. Despite the West Antarctic Ice Sheet’s capacity to retreat and advance quickly over its over-deepened interior, little is known about the subglacial landscape of the East Antarctic elevated interior that probably seeded West Antarctic ice streams and glaciers. At Hercule...
Past interglacial climates with smaller ice sheets offer analogs for ice sheet response to future warming and contributions to sea level rise; however, well-dated geologic records from formerly ice-free areas are rare. Here we report that subglacial sediment from the Camp Century ice core preserves direct evidence that northwestern Greenland was ic...
A hierarchy of general circulation models (GCMs) is used to investigate the linearity of the response of the climate system to changes in Antarctic topography. Experiments were conducted with a GCM with either a slab ocean or fixed SSTs and sea ice, in which the West Antarctic ice sheet (WAIS) and coastal Antarctic topography were either lowered or...
The West Antarctic Ice Sheet (WAIS) may have collapsed during the last interglacial period, between 132,000 and 116,000 years ago. The changes in topography resulting from WAIS collapse would be accompanied by significant changes in Antarctic surface climate, atmospheric circulation, and ocean conditions. Evidence of these changes may be recorded i...
Glaciers in the Amundsen Sea Embayment of West Antarctica are rapidly retreating and contributing to sea level rise. Ice loss is occurring primarily via exposure to warm ocean water, which varies in response to local wind variability. There is evidence that retreat was initiated in the mid-20th century, but the perturbation that may have triggered...
West Antarctica has experienced dramatic ice losses contributing to global sea-level rise in recent decades, particularly from Pine Island and Thwaites glaciers. Although these ice losses manifest an ongoing Marine Ice Sheet Instability, projections of their future rate are confounded by limited observations along West Antarctica’s coastal perimete...
The recovery of long-term climate proxy records with seasonal resolution is rare because of natural smoothing processes, discontinuities and limitations in measurement resolution. Yet insolation forcing, a primary driver of multimillennial-scale climate change, acts through seasonal variations with direct impacts on seasonal climate¹. Whether the s...
Stable water isotope measurements from polar ice cores provide high-resolution information about past hydrologic conditions and are therefore important for understanding earth's climate system. Routine high-resolution measurements of δ18O, δD, and deuterium excess are made by continuous-flow analysis (CFA) methods that include laser spectrometers....
Ocean-driven ice loss from the West Antarctic Ice Sheet is a significant contributor to sea-level rise. Recent ocean variability in the Amundsen Sea sector is primarily controlled by near-surface winds. We combine paleoclimate reconstructions and climate model simulations to understand past and future influences on Amundsen Sea winds from anthropog...
Oxygen and hydrogen isotope ratios in polar precipitation are widely used as proxies for local temperature. In combination, oxygen and hydrogen isotope ratios also provide information on sea surface temperature at the oceanic moisture source locations where polar precipitation originates. Temperature reconstructions obtained from ice-core records g...
Stable water isotope measurements from polar ice cores provide high-resolution information about past hydrologic conditions and are therefore important to understanding Earth's climate system. Routine high-resolution measurements of δ18O, δD, and deuterium excess are made by continuous-flow analysis (CFA) methods that include laser spectroscopy ins...
Plain Language Summary
There are hundreds of subglacial lakes under the Antarctic Ice Sheet. The presence of those lakes requires sufficient heat, sourced either from the Earth's interior or from ice motion. One subglacial lake near the South Pole was previously considered a conundrum since nearby temperature measurements are cold, possibly indicat...
Plain Language Summary
Wind and pressure patterns over the Southern Ocean modulate ocean carbon uptake and may influence the stability of the Antarctic ice sheet. Observations suggest that westerly winds around Antarctica are strengthening and shifting closer to Antarctica. However, modern instrumental observations (i.e., data from satellites, radi...
Over the modern satellite era, substantial climatic changes have been observed in the Antarctic, including atmospheric and oceanic warming, ice sheet thinning and a general Antarctic-wide expansion of sea ice, followed by a more recent rapid loss. Although these changes, featuring strong zonal asymmetry, are partially influenced by increasing green...
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...
Disentangling the drivers of mean annual temperature change in Antarctica requires an understanding of seasonal temperature change. A high-resolution climate record capable of resolving summer and winter seasons could address long-standing questions about the role of orbitally-driven insolation in driving Antarctic mean-annual temperature change. H...
Plain Language Summary
Sea ice variability has a dramatic effect on regional and global climate. Because sea ice extent has such a large summer to winter difference, seasonally specific records of past sea ice conditions are necessary to properly interpret sea ice/climate relationships. Here, we present a sea salt record from the South Pole Ice Cor...
Oxygen and hydrogen isotope ratios in polar precipitation are widely used as proxies for local temperature. Used in combination, oxygen and hydrogen isotope ratios also provide information on sea surface temperature at the oceanic moisture source locations where polar precipitation originates. Temperature reconstructions obtained from ice core reco...
Significance
Understanding Greenland Ice Sheet history is critical for predicting its response to future climate warming and contribution to sea-level rise. We analyzed sediment at the bottom of the Camp Century ice core, collected 120 km from the coast in northwestern Greenland. The sediment, frozen under nearly 1.4 km of ice, contains well-preser...
Plain Language Summary
The Last Interglacial (LIG) period (116,000–130,000 years ago) was globally ∼0.8 °C warmer than today at its peak, with substantially more warming at the poles. It is a valuable analog for future global temperature rise, especially for understanding rates and sources of polar ice melt and subsequent global sea level rise. Rec...
The δD and δ ¹⁸O values of water are key measurements in polar ice-core research, owing to their strong and well-understood relationship with local temperature. Deuterium excess, d, the deviation from the average linear relationship between δD and δ ¹⁸O, is also commonly used to provide information about the oceanic moisture sources where polar pre...
Advances in analytical methods have made it possible to obtain high-resolution water isotopic data from ice cores. Their spectral signature contains information on the diffusion process that attenuated the isotopic signal during the firn densification process. Here, we provide a tool for estimating firn-diffusion rates that builds on the Community...
Winds and pressure over the Southern Ocean are critical to many aspects of the climate system, including ocean circulation and carbon uptake, sea ice extent, and the mass balance of Antarctica. However, reliable climate data around Antarctica begin only in 1979. Here, we reconstruct sea level pressure and zonal surface wind anomalies over the South...
Carbonate clumped isotope measurements (∆47) have been widely applied as a paleothermometer, but various sources of error typically limit their application to anomalies greater than about ±3 °C. Calculation of ∆47 requires a correction for mass interference from ¹⁷O, which traditionally assumes all analytes follow a linear relationship between ¹⁷O/...
In the past 40 years, the global annual mean surface temperature has experienced a non-uniform warming, differing from the spatially uniform warming simulated by the forced responses of large multi-model ensembles to anthropogenic forcing. Rather, it exhibits significant asymmetry between the Arctic and Antarctic, intermittent and spatially varying...
An intermediate-depth (1751 m) ice core was drilled at the South Pole between 2014 and 2016 using the newly designed US Intermediate Depth Drill. The South Pole ice core is the highest-resolution interior East Antarctic ice core record that extends into the glacial period. The methods used at the South Pole to handle and log the drilled ice, the pr...
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...
The Greenland Ice Sheet (GIS) is losing mass at a high rate¹. Given the short-term nature of the observational record, it is difficult to assess the historical importance of this mass-loss trend. Unlike records of greenhouse gas concentrations and global temperature, in which observations have been merged with palaeoclimate datasets, there are no c...
The Last Interglacial (LIG), a warmer period 130,000–116,000 years before present, is a potential analogue for future climate change. Stronger LIG summertime insolation at high northern latitudes drove Arctic land summer temperatures 4–5 °C higher than in the pre-industrial era. Climate model simulations have previously failed to capture these elev...
The American West exemplifies drought-sensitive regions with growing populations. Paleoclimate investigations have documented severe droughts in this region before European settling, with major implications for water management and planning. Here, we leverage paleoclimate data assimilation to reconstruct past climate states, enabling a large-scale...
Reconstructions of past temperature and precipitation are fundamental to modeling the Greenland Ice Sheet and assessing its sensitivity to climate. Paleoclimate information is sourced from proxy records and climate-model simulations; however, the former are spatially incomplete while the latter are sensitive to model dynamics and boundary condition...
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...
The South Pole Ice Core (SPICEcore), which spans the past 54 300 years, was drilled far from an ice divide such that ice recovered at depth originated upstream of the core site. If the climate is different upstream, the climate history recovered from the core will be a combination of the upstream conditions advected to the core site and temporal ch...
Recent ice loss from the West Antarctic Ice Sheet has been caused by ocean melting of ice shelves in the Amundsen Sea. Eastward wind anomalies at the shelf break enhance the import of warm Circumpolar Deep Water onto the Amundsen Sea continental shelf, which creates transient melting anomalies with an approximately decadal period. No anthropogenic...
The Last Millennium Reanalysis (LMR) utilizes an ensemble methodology to assimilate paleoclimate data for the production of annually resolved climate field reconstructions of the Common Era. Two key elements are the focus of this work: the set of assimilated proxy records and the forward models that map climate variables to proxy measurements. Resu...
The South Pole Ice Core (SPICEcore), which spans the past 54,300 years, was drilled far from an ice divide such that ice recovered at depth originated at a location upstream of the current core site. If the climate is different upstream, the climate history recovered from the core will be a combination of the upstream conditions advected to the cor...
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...
Feedbacks between glacier retreat and the solid Earth may slow ice loss from Antarctica
Climate records exhibit scaling behavior with large exponents,
resulting in larger fluctuations at longer timescales. It is unclear
whether climate models are capable of simulating these fluctuations, which draws into question their ability to simulate such
variability in the coming decades and centuries. Using the latest
simulations and data synth...
The relative contribution and physical drivers of internal variability in recent Arctic sea ice loss remain open questions, leaving up for debate whether global climate models used for climate projection lack sufficient sensitivity in the Arctic to climate forcing. Here, through analysis of large ensembles of fully coupled climate model simulations...
The emerging view that the West Antarctic ice sheet is in the early stage of collapse owes as much to paleoclimatology as to contemporary observations.
The interpretation of ice-core records rests on understanding the processes affecting trace constituents of the atmosphere that are preserved in ice. Stable-isotope ratios of ice are widely used as a palaeothermometer, an interpretation backed by well-established theory. In contrast, the interpretation of aerosols such as mineral dust and sea salts...
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...
The Last Millennium Reanalysis utilizes an ensemble methodology to assimilate paleoclimate data for the production of annually resolved climate field reconstructions of the Common Era. Two key elements are the focus of this work: the set of assimilated proxy records, and the forward models that map climate variables to proxy measurements. Results b...
Over the past 20 years satellite remote sensing has captured significant downwasting of glaciers that drain the West Antarctic Ice Sheet into the ocean, particularly across the Amundsen Sea Sector. Along the neighbouring Marie Byrd Land Sector, situated west of Thwaites Glacier to Ross Ice Shelf, glaciological change has been only sparsely monitore...
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...
