Physical Sciences and Mathematics Commons^™

Evidence For Recent Climate Change From Ice Cores In The Central Himalaya, Qin Dahe, Paul Andrew Mayewski, Cameron P. Wake, Kang Shichang, Ren Jiawen, Hou Shugui, Yao Tandong, Yang Qinzhao, Jin Zhefan, Mi Desheng

Earth Science Faculty Scholarship

Comparison of the terminus locations of Rongbuk Glacier, Mount Everest, measured in 1966 and 1997 shows that in the past 30 years the glacier has retreated 170-270 m, equivalent to a retreat speed of 5.5-8.7 m a⁻¹. During summer 1997, a 15 m firn core was recovered from Dasuopu glacier (28°23′N, 85°44′E; 7000 m a.s.l.) on the northwest margin of Xixabangma Feng, Xizang (Tibet). The seasonal variations of δ¹⁸O values in the core indicate that monsoon signals are clearly recorded in the glacier. δ¹⁸O values are controlled by the amount effect in the monsoon …

Monsoon And Dust Signals Recorded In Dasuopu Glacier, Tibetan Plateau, Kang Shichang, Cameron P. Wake, Qin Dahe, Paul Andrew Mayewski, Yao Tandong

Earth Science Faculty Scholarship

During summer 1997, a 15m firn core was recovered from Dasuopu glacier (28°23'N, 85° 44' E; 7000 m a.s.l.) on the northwest margin of Xixabangma Feng in the central Himalaya. Oxygen isotope values and concentrations of Ca²⁺, Mg²⁺, NH₄⁺, SO₄^2- and NO₃^- were measured over the 10 years of snow accumulation captured in the firn core. The seasonal variations of δ¹⁸O values and major-ion concentrations in the Dasuopu core indicated that summer monsoon and dust signals are clearly recorded in Dasuopu glacier. Annual variations in the δ …

Maximum Temperature Trends In The Himalaya And Its Vicinity: An Analysis Based On Temperature Records From Nepal For The Period 1971-94, Arun B. Shrestha, Camerson P. Wake, Paul Andrew Mayewski, Jack E. Dibb

Earth Science Faculty Scholarship

Analyses of maximum temperature data from 49 stations in Nepal for the period 1971-94 reveal warming trends after 1977 ranging from 0.06° to 0.12°C yr¹ in most of the Middle Mountain and Himalayan regions, while the Siwalik and Terai (southern plains) regions show warming trends less than 0.03°C yr¹. The subset of records (14 stations) extending back to the early 1960s suggests that the recent warming trends were preceded by similar widespread cooling trends. Distributions of seasonal and annual temperature trends show high rates of warming in the high-elevation regions of the country (Middle Mountains and Himalaya), …

Antarctic's Role Pursued In Global Climate Change, Paul Andrew Mayewski, I. Goodwin

Earth Science Faculty Scholarship

The impact of Antarctica on global climate change and the impact of global climate change on Antarctica are the focal points of a current series of expeditions there, and an international, interdisciplinary array of researchers met this past spring to go over the expeditions' progress. Advances were reported in describing the impact of the seasonal cycle, semiannual oscillation, and the El Niño-Southern Oscillation (ENSO) cycle on Antarctic accumulation in recent decades.

Difficulties still remain, however, in explaining fully the history and forcing of the Antarctic climate and the links between tropical forcing and high-latitude response. The difficulties arise largely because …

Spatial Variability Of Climate And Past Atmospheric Circulation Patterns From Central West Antarctic Glaciochemistry, David B. Reusch, Paul Andrew Mayewski, Sallie I. Whitlow, Iqbal I. Pittalawa, Mark S. Twickler

Earth Science Faculty Scholarship

Atmospheric circulation patterns and the spatial variability of atmospheric chemistry and moisture transport in central West Antarctica are investigated using new 40 year long (1954–1994 A.D.) glaciochemical and accumulation rate records developed from four firn cores from this region. The core sites lie on a 200 km traverse from 82° 22′ S, 119° 17′ W to 81° 22′ S, 107° 17′ W. The glaciochemical records represent the major ionic species present in Antarctic snow: Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl⁻, NO₃⁻, and SO₄²⁻. High spatial …

The Weddell Sea Region: An Important Precipitation Channel To The Interior Of The Antarctic Ice Sheet As Revealed By Glaciochemical Investigation Of Surface Snow Along The Longest Trans-Antarctic Route, Qin Dahe, Paul Andrew Mayewski, Ren Jiawen, Xiao Cunde, Sun Junying

Earth Science Faculty Scholarship

Glaciochemical analysis of surface snow samples, collected along a profile crossing the Antarctic ice sheet from the Larsen Ice Shelf, Antarctic Peninsula, via the Antarctic Plateau through South Pole, Vostok and Komsomolskaya to Mirny station (at the east margin of East Antarctica), shows that the Weddell Sea region is an important channel for air masses to the high plateau of the Antarctic ice sheet (>2000 m a.s.l.). This opinion is supported by the following. (1) The fluxes of sea-salt ions such as Na⁺, Mg²⁺ and Cl⁻ display a decreasing trend from the west to the …

Seasonal Variations Of Glaciochemical, Isotopic And Stratigraphic Properties In Siple Dome (Antarctica) Surface Snow, K. J. Kreutz, Paul Andrew Mayewski, M. S. Twickler, S. I. Whitlow, J. W.C. White, C. A. Shuman, C. F. Raymond, H. Conway, J. R. Mcconnell

Earth Science Faculty Scholarship

Six snow-pit records recovered from Siple Dome, West Antarctica, during 1994 are used to study seasonal variations in chemical (major ion and H2O2), isotopic (deuterium) and physical stratigraphic properties during the 1988-94 period. Comparison of dD measurements and satellite-derived brightness temperature for the Siple Dome area suggests that most seasonal dD maxima occur within ±4 weeks of each 1 January. Several other chemical species (H2O2, non-sea-salt (nss) SO42-, methanesulfonic acid and NO3-) show coeval peaks with dD, together providing an accurate method for identifying summer accumulation. Sea-salt-derived species generally peak during winter/spring, but episodic input is noted throughout some years. …

Climatological Significance Of Δ18O In Precipitation And Ice Cores: A Case Study At The Head Of The Ürütnqi River, Tien Shan, China, Hou Shugui, Qin Dahe, Paul Andrew Mayewski, Yang Qinzhao, Ren Jiawen, Li Zhongqin, Xiao Cunde

Earth Science Faculty Scholarship

Stable-oxygen-isotope ratios (δ¹⁸O) collected from the headwaters of the Ürümqi river, Tien Shan, China, were used to test the relationship between δ¹⁸O temporal relationship is found between δ¹⁸O monthly averages which remove synoptic-scale influences such as changes in condensation level, condensation temperature and moisture sources (Yao and others, 1996). Linear fits as high as 0.95‰°C^-1 for precipitation events and 1.23‰°C^-1 for monthly averages are found. Although the δ¹⁸O (∼2 km from the precipitation sampling site) decreased dramatically compared to the precipitation samples , the ice-core records of annually averaged δ …

Soluble Species In Aerosol And Snow And Their Relationship At Glacier 1, Tien Shan, China, Junying Sun, Dahe Qin, Paul Andrew Mayewski, Jack E. Dibb, Sallie Whitlow, Zhongqin Li, Qinzhao Yang

Earth Science Faculty Scholarship

Simultaneous sampling of aerosol (n = 20) and snow (n = 114) was made at Glacier 1, Tien Shan, between May 19 and June 29, 1996. Similar temporal patterns of some major ion (calcium, magnesium, potassium, sodium, chloride, and sulfate) concentrations between snow and aerosol show that snow chemistry basically reflects changes in the chemistry of the atmosphere. This gives us confidence in the reconstruction of past atmospheric change using some snow data. There are no significant correlations between aerosol and snow samples for ammonium and nitrate. This suggests that postdepositional and/or postcollection processes may alter ammonium and …

Limited Migration Of Soluble Ionic Species In A Siple Dome, Antarctica, Ice Core, Karl J. Kreutz, Paul Andrew Mayewski, Sallie I. Whitlow, Mark S. Twickler

Earth Science Faculty Scholarship

High-resolution (>10 samples a ^-1) glaciochemical analyses covering the last 110 years from a Siple Dome, Antarctica, ice core reveal limited migration of certain soluble ionic species (methane sulfonic acid, NO₃ and Mg²⁺). Th e observed chemical migration m ay be due in part to seasonal alternation between less acidic winter (from high sea-salt concentrations) and m ore acidic summer (from high marine biogenic acid concentrations) layers, common at coastal sites such as Siple Dome. Exact mechanisms to explain the migration are unclear, although simple diffusion and gravitational movement are unlikely since new peaks are …

Spatial Variability Of Snow Chemistry In Western Dronning Maud Land, Antarctica, Malin Stenberg, Elisabeth Isaksson, Margareta Hansson, Wibjörn Karlén, Paul Andrew Mayewski, Mark S. Twickler, Sallie I. Whitlow, Niels Gundestrup

Earth Science Faculty Scholarship

During the austral summer of 1993-94 a number of 1-2 m deep snow pits were sampled in connection with firn-coring in western Dronning Maud Land, Antarctica. The traverse went from 800 to about 3000 m a.s.l. upon the high-altitude plateau. Profiles of cations (Na⁺, K⁺, Mg²⁺, Ca²⁺), anions (CI^-, NO^3-, SO₄^2-, CH₃SO₃^-) and stable oxygen isotopes (δ¹⁸O) from II snow pits are presented here. Close to the coast 2 m of snow accumulates in about 2-3 years, whilst …

Assessment Of The Record Of The 1982 El Chichón Eruption As Preserved In Greenland Snow, Gregory A. Zielinski, Jack E. Dibb, Qinzhao Yang, Paul Andrew Mayewski, Sallie Whitlow, Mark S. Twickler, Mark S. Germani

Earth Science Faculty Scholarship

Variability in the SO 4 2 - and Cl⁻ time series for the 1980s from 12 shallow snow pits across the Greenland ice sheet is used to evaluate the record of the 1982 El Chichón eruption and the potential for recording a moderate northern equatorial eruption in a single Greenland ice core. Composition of volcanic glass found in spring 1983 snow in one of the pits in the Summit region matches that from El Chichón glass, thereby verifying the deposition of material from the eruption. High Na⁺ and Cl⁻ concentrations in this same layer probably represent deposition …

A 110,000-Year History Of Change In Continental Biogenic Emissions And Related Atmospheric Circulation Inferred From The Greenland Ice Sheet Project Ice Core, L. D. Meeker, Paul Andrew Mayewski, M. S. Twickler, S. I. Whitlow, D. Meese

Earth Science Faculty Scholarship

The 110,000-year record of ammonium concentrations from the Greenland Ice Sheet Project 2 (GISP2) ice core provides the basis for an analysis of terrestrial biological production and atmospheric circulation patterns involved in the transport of biologically produced ammonium to the Greenland atmosphere. The directly measured concentration series was selected for analysis, rather than that of estimated ammonium flux, after a detailed analysis of the relationship among ice core glaciochemical concentrations and a high-resolution simultaneous record of snow accumulation from the GISP2 core. Analysis of the ammonium concentration series shows that maxima in background levels of ammonium in the Greenland atmosphere …

The Co2 Concentration Of Air Trapped In Greenland Ice Sheet Project 2 Ice Formed During Periods Of Rapid Climate Change, H. J. Smith, M. Wahlen, D. Mastroianni, K. Taylor, Paul Andrew Mayewski

Earth Science Faculty Scholarship

The CO₂ content of air occluded in Greenland Ice Sheet Project 2 (GISP2) ice formed over two separate intervals of rapidly changing climate, centered at approximately 46 and 63 kyr B. P., is as much as 90 ppm more during warm periods (interstadials) than during cold periods (stadials). These CO₂ variations are superimposed on changes in annual layer thickness and δ¹⁸O of the ice and do not show the 200- to 700-year offsets which would be expected for concurrent variations in the atmosphere and the ice. The CO₂ concentrations during the stadials are similar to …

Electrical Measurements On The Greenland Ice Sheet Project 2 Core, Kendrick C. Taylor, Richard B. Alley, Gregg W. Lamorey, Paul Andrew Mayewski

Earth Science Faculty Scholarship

The Greenland Ice Sheet Project 2 (GISP2) electrical conductivity measurement (ECM) record is an indication of the concentration of H+ in the core. The ECM detected seasonal variations in the nitrate concentration of the core which were used to assist in dating the core by annual layer counting. Volcanic eruptions that produce acidic aerosols are recorded in the ECM record. Evidence of biomass burning is detected by the ECM because fire-related ammonium emissions neutralize the acids in the core. Rapid climate transitions associated with the Younger Dryas and Dansgaard/Oeschger interstadial events alter the concentration of alkaline dust and are detected …

Paleoclimatic Variability Inferred From The Spectral Analysis Of Greenland And Antarctic Ice-Core Data, R. Yiou, K. Fuher, L. D. Meeker, J. Jouzel, S. Johnsen, Paul Andrew Mayewski

Earth Science Faculty Scholarship

Paleoclimate variations occur at various time scales, between a few centuries for the Heinrich events and several hundreds of millenia for the glacial to interglacial variations. The recent ice cores from Greenland (Greenland Ice Core Project and Greenland Ice Sheet Project 2) and Antarctica (Vostok) span at least one glacial oscillation and provide many opportunities to investigate climate variations with a very fine resolution. The joint study of cores from both hemispheres allows us to distinguish between the sources of variability and helps to propose mechanisms of variations for the different time scales involved. The climate proxies we analyze are …

The Greenland Ice Sheet Project 2 Depth-Age Scale: Methods And Results, D. A. Meese, A. J. Gow, R. B. Alley, G. A. Zielinski, P. M. Grootes, M. Ram, K. C. Taylor, Paul Andrew Mayewski, J. F. Bolzan

Earth Science Faculty Scholarship

The Greenland Ice Sheet Project 2 (GISP2) depth-age scale is presented based on a multiparameter continuous count approach, to a depth of 2800 m, using a systematic combination of parameters that have never been used to this extent before. The ice at 2800 m is dated at 110,000 years B.P. with an estimated error ranging from 1 to 10% in the top 2500 m of the core and averaging 20% between 2500 and 2800 m. Parameters used to date the core include visual stratigraphy, oxygen isotopic ratios of the ice, electrical conductivity measurements, laser-light scattering from dust, volcanic signals, and …

Volcanic Aerosol Records And Tephrochronology Of The Summit, Greenland, Ice Cores, Gregory A. Zielinski, Paul Andrew Mayewski, L. David Meeker, Karl Grönvold, Mark D. Germani, Sallie Whitlow, Mark S. Twickler, Kendrick Taylor

Earth Science Faculty Scholarship

The recently collected Greenland Ice Sheet Project 2 (GISP2) and Greenland Ice Core Project ice cores from Summit, Greenland, provide lengthy and highly resolved records of the deposition of both the aerosol (H₂SO₄) and silicate (tephra) components of past volcanism. Both types of data are very beneficial in developing the hemispheric to global chronology of explosive volcanism and evaluating the entire volcanism-climate system. The continuous time series of volcanic SO₄²⁻ for the last 110,000 years show a strong relationship between periods of increased volcanism and periods of climatic change. The greatest number of volcanic …

Major Features And Forcing Of High-Atitude Northern Hemisphere Atmospheric Circulation Using A 110,000-Year-Long Glaciochemical Series, Paul Andrew Mayewski, Loren D. Meeker, Mark S. Twickler, Sallie Whitlow, Qinzhao Yang, W. Berry Lyons, Michael Prentice

Earth Science Faculty Scholarship

The Greenland Ice Sheet Project 2 glaciochemical series (sodium, potassium, ammonium, calcium, magnesium, sulfate, nitrate, and chloride) provides a unique view of the chemistry of the atmosphere and the history of atmospheric circulation over both the high latitudes and mid-low latitudes of the northern hemisphere. Interpretation of this record reveals a diverse array of environmental signatures that include the documentation of anthropogenically derived pollutants, volcanic and biomass burning events, storminess over marine surfaces, continental aridity and biogenic source strength plus information related to the controls on both high- and low-frequency climate events of the last 110,000 years. Climate forcings investigated …

Methanesulfonate In The Greenland Ice Sheet Project 2 Ice Core, E. S. Saltzman, P-Y. Whung, Paul Andrew Mayewski

Earth Science Faculty Scholarship

In this paper we present measurements of methanesulfonate in the Greenland Ice Sheet Project 2 (GISP2) ice core. Methanesulfonate is an atmospheric oxidation product of dimethylsulfide. The GISP2 methanesulfonate record contains information about the atmospheric loading of biogenic sulfur over the past 110 kyr and its relationship to climate change. The GISP2 data set supports the inferences made from the Renland ice core from Greenland that the glacial atmosphere over Greenland had reduced concentrations of biogenic sulfur compared with the present day [Hansson and Saltzman, 1993]. We conclude that the flux of biogenic sulfur from the North Atlantic Ocean …

Major Features Of Glaciochemistry Over The Last 110,000 Years In The Greenland Ice Sheet Project 2 Ice Core, Qinzhao Yang, Paul Andrew Mayewski, Marks S. Twickler, Sallie Whitlow

Earth Science Faculty Scholarship

Major chemical species (Cl⁻, NO 3 - , SO 4 2 - , Na⁺, NH 4 + , K⁺, Mg²⁺, Ca²⁺) and δ¹⁸O covering the last 110,000 years from the Greenland Ice Sheet Project 2 (GISP2) ice core were utilized in this study in order to reconstruct the soluble chemistry of the atmosphere over Greenland and interpret major climate events that have affected the region. During the Holocene the major chemical species and δ¹⁸O do not display any significant relationship. However, a strong inverse correlation was …

Glaciochemistry Of Polar Ice Cores: A Review, Michel Legrand, Paul Andrew Mayewski

Earth Science Faculty Scholarship

Human activities have already modified the chemical composition of the natural atmosphere even in very remote regions of the world. The study of chemical parameters stored in solid precipitation and accumulated on polar ice sheets over the last several hundred thousand years provides a unique tool for obtaining information on the composition of the preindustrial atmosphere and its natural variability over the past. This paper deals with the chemistry of polar ice focused on the soluble mineral (Na⁺, NH₄⁺, K⁺, Ca⁺⁺, Mg⁺⁺, H⁺, F⁻, Cl …

Glaciochemical Studies At Siple Dome, West Antarctica, During The 1996–1997 Season, Karl J. Kreutz, Paul Andrew Mayewski, Mark S. Twickler, Sallie I. Whitlow, L. David Meeker

Earth Science Faculty Scholarship

Deep ice cores collected from the interior of the west antarctic ice sheet and the interice stream ridges along the Siple Coast potentially contain long time-series records of Southern Hemisphere environmental change. One such location is Siple Dome, an approximately l20-kilometer (km) x 250-km ice dome located between ice streams C and D (figure 1). Because of promising results from reconnaissance glaciochemical (Mayewski, Twickler, and Whitlow 1995) and geophysical (Raymond et al. 1995) research, current U.S. deep ice-coring efforts are focused in the area. Drilling at Siple Dome is advantageous for several reasons, including the site's relatively simple geometry and …

Historical Biomass Burning: Late 19th Century Pioneer Agriculture Revolution In Northern Hemisphere Ice Core Data And Its Atmospheric Interpretation, G. Holdsworth, K. Hiuchi, G. A. Zielinski, Paul Andrew Mayewski, M. Wahlen, B. Deck, P. Chylek, B. Johnson, P. Damiano

Earth Science Faculty Scholarship

Ice core data from Yukon and Greenland spanning from ∼1750 to 1950 indicate that between ∼1850 and ≤1910 a clear atmospheric signal exists of an episodic biomass burning event that is referred to as the Pioneer Agriculture Revolution. This is best seen in NH₄⁺ ion and particulate concentrations but also in some limited black carbon concentration data, where for all three quantities maximum levels reach about 3 times the prerevolution background concentrations. Tree cellulose δ¹³C data and some early, controversial, French, air CO₂ data, occurring within the same time interval, are interpreted as providing other …

Depletion Of Atmospheric Nitrate And Chloride As A Consequence Of The Toba Volcanic Eruption, Q. Yang, Paul Andrew Mayewski, G. A. Zielinski, M. Twickler, K. C. Taylor

Earth Science Faculty Scholarship

Continuous measurements of SO₄²⁻ and electrical conductivity (ECM) along the GISP2 ice core record the Toba mega‐eruption at a depth 2590.95 to 2091.25 m (71,000±5000 years ago). Major chemical species were analyzed at a resolution of 1 cm per sample for this section. An ∼6‐year long period with extremely high volcanic SO₄²⁻ coincident with a 94% depletion of nitrate and 63% depletion of chloride is observed at the depth of the Toba horizon. Such a reduction of chloride in a volcanic layer preserved in an ice core has not been observed in any previous studies. The …

Relationship Between Continuous Aerosol Measurements And Firn Core Chemistry Over A 10‐Year Period At The South Pole, M. H. Bergin, E. A. Meyerson, J. E. Dibb, Paul Andrew Mayewski

Earth Science Faculty Scholarship

Before ice core chemistry can be used to estimate past atmospheric chemistry it is necessary to establish an unambiguous link between concentrations of chemical species in the air and snow. For the first time a continuous long‐term record of aerosol properties (aerosol light scattering coefficient, σ_sp , and Ångström exponent, å) at the South Pole are compared with the chemical record from a high resolution firn core (∼10 samples per year) covering the period from 1981 to 1991. Seasonal signals in å, associated with winter minima due to coarse mode seasalt and summer maxima due to accumulation mode sulfate …

Chemical Species Spatial Distribution And Relationship To Elevation And Snow Accumulation Rate Over The Greenland Ice Sheet, Q. Yang, Paul Andrew Mayewski, E. Linder, S. Whitlow, M. Twickler

Earth Science Faculty Scholarship

Major chemical species (Cl⁻, NO⁻₃, SO²⁻₄, Na⁺, K⁺, Mg²⁺, Ca²⁺) from 24 snowpits (sampled at a resolution of 3 cm, total 2995 samples) collected from northern, central, and southern Greenland were used for this investigation. The annual and seasonal (winter and summer) concentration of each chemical species was calculated and used to study the spatial distribution of chemical species over the central portion of the Greenland Ice Sheet. A two-sided t-distribution test (α=0.05) suggests that concentrations of major chemical species in snow do …

Twin Ice Cores From Greenland Reveal History Of Climate Change, More, R. Alley, Paul Andrew Mayewski, D. Peel, B. Stauffer

Earth Science Faculty Scholarship

Two projects conducted from 1989 to 1993 collected parallel ice cores—just 30 km apart— from the central part of the Greenland ice sheet. Each core is more than 3 km deep and extends back 110,000 years. In short, the ice cores tell a clear story: humans came of age agriculturally and industrially during the most stable climatic regime recorded in the cores. Change—large, rapid, and global—is more characteristic of the Earth's climate than is stasis.

Potential Atmospheric Impact Of The Toba Mega‐Eruption ∼71,000 Years Ago, G. A. Zielinski, Paul Andrew Mayewski, L. D. Meeker, S. Whitlow, M. S. Twickler, K. Taylor

Earth Science Faculty Scholarship

An ∼6‐year long period of volcanic sulfate recorded in the GISP2 ice core about 71,100 ± 5000 years ago may provide detailed information on the atmospheric and climatic impact of the Toba mega‐eruption. Deposition of these aerosols occur at the beginning of an ∼1000‐year long stadial event, but not immediately before the longer glacial period beginning ∼67,500 years ago. Total stratospheric loading estimates over this ∼6‐year period range from 2200 to 4400 Mt of H₂SO₄ aerosols. The range in values is given to compensate for uncertainties in aerosol transport. Magnitude and longevity of the atmospheric loading may …

A Century Of Accumulation And Temperature Changes In Dronning Maud Land, Antarctica, Elisabeth Isaksson, Wibjörn Karlén, Niels Gundestrup, Paul Andrew Mayewski, Sallie Whitlow, Mark Twickler

Earth Science Faculty Scholarship

A mass balance program was initiated in the Vestfjella-Heimefrontfjella area of western Dronning Maud Land during the austral summer of 1988–1989. As a part of this program, spatial and temporal variations in snow accumulation and temperature/stable isotopes are measured using shallow firn cores. In this paper we present surface accumulation data and discuss the climatic implications of the stable isotope records from two shallow firn cores. One 30-m-deep core, obtained about 200 km from the coast at 700 m asl (73°36′S, 12°26′W), covers the period 1932–1991. The other core was drilled at about 500 km from the coast at 2900 …