A5018099448- Geology and Paleoclimatology Research
- Cryospheric studies and observations
- Climate change and permafrost
- Methane Hydrates and Related Phenomena
- Arctic and Antarctic ice dynamics
- Climate variability and models
- Atmospheric and Environmental Gas Dynamics
- Isotope Analysis in Ecology
- Landslides and related hazards
- Winter Sports Injuries and Performance
- Geological Studies and Exploration
- Meteorological Phenomena and Simulations
- Geochemistry and Geologic Mapping
- Heavy metals in environment
- Mercury impact and mitigation studies
- Radioactivity and Radon Measurements
- Atmospheric chemistry and aerosols
- Polar Research and Ecology
- Indigenous Studies and Ecology
- Aeolian processes and effects
- Radioactive contamination and transfer
- Pleistocene-Era Hominins and Archaeology
- Geological formations and processes
- COVID-19 and healthcare impacts
- Groundwater and Isotope Geochemistry
Dartmouth College
2015-2024
Dartmouth Hospital
2014-2019
University of Maine
2005-2013
Earth and Space Research
2013
University of Colorado Boulder
2013
University of Washington
2013
University of Otago
2006-2007
We present a novel ice/firn core melter system that uses fraction collectors to collect discrete, high-resolution (<1 cm/sample possible), continuous, coregistered meltwater samples for analysis of eight major ions by ion chromatography (IC), >32 trace elements inductively coupled plasma sectorfield mass spectrometry (ICP-SMS), and stable oxygen hydrogen isotopes isotope ratio (IRMS). The new continuous melting with discrete sampling (CMDS) preserves an archive each sample, reduces the...
Abstract The northeastern United States has experienced a large increase in precipitation over recent decades. Annual and seasonal changes of total extreme from station observations the Northeast were assessed multiple time periods spanning 1901–2014. Spatially averaged, both annual across increased significantly since 1901, with changepoints occurring 2002 1996, respectively. larger than precipitation; 1996 to 2014 is 53% higher 1901 1995. Spatially, coastal areas receive more on average,...
The ice core recovered from Prospector Russell Col on Mt Logan (5.4 km a.s.l.), in the Yukon spans over 20 000 years. This unique record offers a Pacific view of stable isotope and chemical Lateglacial to present. timescale is based seasonal counted years, largest known volcanic acid signatures major shift isotopes chemistry at end Younger Dryas. There are large sustained changes isotopic that anti-correlated with marine continental series. oxygen-18 this area not proxy for palaeotemperature...
Abstract An updated compilation of published and new data major-ion (Ca, Cl, K, Mg, Na, NO 3 , SO 4 ) methylsulfonate (MS) concentrations in snow from 520 Antarctic sites is provided by the national ITASE (International Trans-Antarctic Scientific Expedition) programmes Australia, Brazil, China, Germany, Italy, Japan, Korea, New Zealand, Norway, United Kingdom, States programme Finland. The comparison shows that chemistry vary up to four orders magnitude across Antarctica exhibit distinct...
A high‐resolution, 8000 year‐long ice core record from the Mt. Logan summit plateau (5300 m asl) reveals initiation of trans‐Pacific lead (Pb) pollution by ca. 1730, and a >10‐fold increase in Pb concentration (1981–1998 mean = 68.9 ng/l) above natural background (5.6 attributed to rising anthropogenic emissions Asia. The largest rise North Pacific 1970–1998 (end record) is contemporaneous with decrease Eurasian American as documented records Greenland, Devon Island, European Alps....
Abstract Future precipitation changes in a warming climate depend regionally upon the response of natural modes to anthropogenic forcing. North Pacific hydroclimate is dominated by Aleutian Low, semi-permanent wintertime feature characterized frequent low-pressure conditions that influenced tropical Ocean temperatures through Pacific-North American (PNA) teleconnection pattern. Instrumental records show recent increase coastal Alaskan and Low intensification, but are insufficient length...
Past emissions of the toxic metal mercury (Hg) persist in global environment, yet these remain poorly constrained by existing data. Ice cores are high-resolution archives atmospheric deposition that may provide crucial insight into past Hg levels during recent and historical time. Here we present a record total (HgT) an ice core from pristine summit plateau (5340 m asl) Mount Logan, Yukon, Canada, representing AD 1410 to 1998. The Colonial Period (∼1603–1850) North American “Gold Rush”...
Abstract Future changes in North Pacific wintertime climate will be largely determined by the response of Aleutian Low (ALow) pressure system to anthropogenic forcing. Although ALow has intensified over twentieth century, global model projections future variability are equivocal. In order evaluate decadal centennial forcing mechanisms and provide context for modern intensification, here we combine a new Denali ice core (Alaska) sea‐salt sodium record with Mount Logan (Yukon) develop...
Significance Reconstructions of climate over Greenland during past warm periods provide crucial insights into the likely response Ice Sheet to future warming. However, limited preservation interglacial archives due extensive glacial scouring has hindered paleoclimate reconstructions along Greenland’s margins. Here, we report a lake sediment record that preserves both present and previous periods. This record, combined with prior studies, demonstrates exceptionally strong warming northern...
Higher boreal summer insolation in the early to middle Holocene drove thousands of years warming across Arctic. Modern-day has distinctly different causes, but geologic data from this past warm period hold lessons for future. We compile temperature reconstructions ice, lake, and marine cores around Greenland, where temperatures are globally important due their influence on ice sheet mass balance, ocean circulation, sea ice. Highlighting accounting some key issues with proxy interpretation,...
Abstract In 1996, the northeastern United States experienced an abrupt increase in extreme precipitation, but causal mechanisms driving this remain poorly understood. We find that 89% of 1996–2016 relative to 1979–1995 is explained by only 273 unique events affecting >5 stations and occurring months February, March, June, July, September, October. use daily weather maps classify precipitation meteorological cause (tropical cyclones, fronts, extratropical cyclones) reanalysis data...
Abstract Refreezing of meltwater in firn is a major component Greenland ice-sheet's mass budget, but situ observations are rare. Here, we compare the density and total ice layer thickness upper 15 m 19 new 27 previously published cores drilled at locations southwest (1850–2360 a.s.l.) between 1989 2019. At all sites, covaries with over time space. two sites earliest (1989 1998), bulk increased by 15–18%, top 28 21 years, respectively. However, following extreme melt 2012, elevation-detrended...
Abstract Variability in sea ice is a critical climate feedback, yet the seasonal behavior of Southern Hemisphere and across multiple timescales remains unclear. Here, we develop seasonally resolved Holocene salt record using major ion measurements South Pole Ice Core (SPC14). We combine SPC14 data with GEOS‐Chem chemical transport model to demonstrate that primary source switches from open water (summer) (winter), wintertime variations disproportionately responsible for centennial millennial...
High‐resolution major and trace elements (Sr, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, U, Tl, Al, S, Ca, Ti, V, Cr, Mn, Fe, Co) quantified in a Mount Everest ice core (6518 m above sea level) spanning the period 1650–2002 AD provides first Asian record of element concentrations from pre‐industrial era, continuous high‐resolution which natural baseline subsequent changes due to anthropogenic activities can be examined. Modern most remain within range; however, Cs their...
Abstract Accumulation is a key parameter governing the mass balance of Greenland ice sheet. Several studies have documented spatial variability accumulation over wide scales, primarily using point data, remote sensing or modeling. Direct measurements spatially extensive, detailed profiles in Greenland, however, are rare. We used 400 MHz ground-penetrating radar along 1009 km route Inland Traverse from Thule to Summit during April and May 2011, image continuous internal reflecting horizons....
Abstract Remote sensing observations and climate models indicate that the Greenland Ice Sheet (GrIS) has been losing mass since late 1990s, mostly due to enhanced surface melting from rising summer temperatures. However, in situ observational records of GrIS melt rates over recent decades are rare. Here we develop a record frozen meltwater west percolation zone preserved seven firn cores. Quantifying ice layer distribution as feature percentage (MFP), find significant increases MFP...
Abstract. The South Pole Ice Core (SPICEcore) was drilled in 2014–2016 to provide a detailed multi-proxy archive of paleoclimate conditions East Antarctica during the Holocene and late Pleistocene. Interpretation these records requires an accurate depth–age relationship. Here, we present SPICEcore (SP19) timescale for age ice SPICEcore. SP19 is synchronized WD2014 chronology from West Antarctic Sheet Divide (WAIS Divide) core using stratigraphic matching 251 volcanic events. These events...
Abstract We present a novel approach to characterize the spatiotemporal evolution of regional cooling across eastern United States (commonly called U.S. warming hole), by defining spatially explicit boundary around region most persistent cooling. The hole emerges after regime shift in 1958 where annual maximum ( T max ) and minimum min temperatures decreased 0.83°C 0.46°C, respectively. consists two distinct seasonal modes, one located southeastern during winter spring other midwestern...
Extreme precipitation (EP) in the Northeastern United States increased abruptly after 1996, coinciding with warming Atlantic sea surface temperatures (SSTs). We examine importance of internal variability and external forcings (including anthropogenic natural forcings) to these EP SST increases by using Community Earth System Model large ensembles an optimal fingerprint method isolate effects different on 1929–2018 Northeast North SSTs. find that have significantly influenced both SSTs, a...
Three ice cores recovered on or near Mount Logan, together with a nearby lake record (Jellybean Lake), cover variously 500 to 30 000 years. This suite of records offers unique view the lapse rate in stable isotopes from lower upper troposphere. The region is climatologically important, being beside Cordilleran pinning-point Rossby Wave system and Aleutian Low. Comparison isotope series over last 2000 years model simulations suggest sudden persistent shifts between modern (mixed) zonal flow...
Abstract Continuous, high‐resolution paleoclimate records from the North Pacific region spanning past 1500 years are rare; and behavior of Aleutian Low (ALow) pressure center, dominant climatological feature in Gulf Alaska, remains poorly constrained. Here we present a continuous, year long, calibrated proxy record for strength wintertime (December–March) ALow Mount Logan summit (PR Col; 5200 m asl) ice core soluble sodium time series. We show that concentrations statistically correlated...
Abstract. The mass balance of the Greenland Ice Sheet (GrIS) in a warming climate is critical interest to scientists and general public context future sea-level rise. An improved understanding temporal spatial variability snow accumulation will reduce uncertainties GrIS models improve projections Greenland's contribution rise, currently estimated at 0.089 ± 0.03 m by 2100. Here we analyze 25 NASA Operation IceBridge radar flights totaling > 17 700 km from 2013 2014 determine dry...
Abstract. A new ice core drilled at the South Pole provides a 54 000-year paleoenvironmental record including composition of past atmosphere. This paper describes SP19 chronology for atmospheric gas and complements previous (Winski et al., 2019) describing chronology. The is based on discrete methane (CH4) with 20- to 190-year resolution. To construct timescale, abrupt changes in CH4 during glacial period centennial variability Holocene were used synchronize analogous data from West...