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800,000-year Ice-Core Records of Aerosols
This page introduces records of dust in Antarctic ice-cores that now extend back about 800,000 years at Dome C and over 400,000 years at the Vostok site. Click here to see modern records of specific aerosol types from locations around the world. The longest records are available at the EPICA Dome C site (~800,000 years) and the Vostok site (~422,000 years). The Byrd Station site has some undated records listed by depth. Shorter records are available for Arctic stations and tropical mountain glaciers, as specified below.
Unlike carbon dioxide, methane, nitrous oxide and halocarbons, dust is not evenly distributed in the atmosphere. Like cloud water droplets, it tends to fall out as it travels away from its source, precluding an even distribution over the planet. Nonetheless, dust records in ice cores can provide useful information about climate, as well as about occurrences of very large volcanos which can cool the atmosphere for a few years. In Antarctica, the amount of dust deposited was much higher during glacial times, when percentages of deuterium in the ice are lower due to the increased condensation and removal of heavier water molecules from cooling air as it moves toward and over the Antarctic continent. When combined with information about the mineral composition of the dust, which is indicative of its origin, one can make inferences about changes in the general circulation in the atmosphere at high latitudes in the Southern Hemisphere during glacial and interglacial periods. Volcanic dust can be used to establish time scales for the ice-core chronologies. The dust from a volcano starts to fall out shortly after the volcano occurred, so that the dates of known volcanos can be used to provide time cconstraints for the ice cores. For a prehistoric volcano, its dust-layer signature (in mineral composition) should occur in the same years at all ice-core sites, thus facilitating synchronization of the ice-core chronologies.
Units are not consistent from one ice-core record to the next; sometimes the mass of particulate matter, or of particulate matter greater than a specified size, is given for a specified time period or range of depth. In other cases the mass ratio, typically in nanograms per gram of material sampled or in nanograms of dust per liter of (melted) material sampled is given; one nanogram = 10-9 grams. Watch the units carefully.
Dome C 800,000-year Record
European Project for Ice Coring in Antarctica (EPICA) members: D., M. Le Floch, B. Bereiter, T. Blunier, J.-M. Barnola, U. Siegenthaler, D. Raynaud, J. Jouzel, H. Fischer, K. Kawamura, and T.F. Stocker.
Vostok 400,000-plus-year Record
J.R.Petit, Laboratoire de Glaciologie et Géophysique de l'Environnement, Grenoble, France.
Lonnie G. Thompson, Byrd Polar Research Center of the Ohio State University
D.A. Fisher, Polar Continental Shelf Project, Canada
Collective Period of Record
Back to ~800,000 years before "present" ("present" = 1950).
Maps showing locations of ice-core dust samples from Devon Island (75° N 82° W), Camp Century (77°N, 61°W), GISP2 (73°N, 38°W), Penny, Baffin Island (67°N, 66°W), Huascaran (9°S, 77°W), Quelcacca (14°S' 71°W), Sajama(18°S, 69°W), Lewis Glacier, Kenya (0°S, 37°E), Byrd Station (80°01'S, 119°31'W), Dome C (75°06'S, 123°24'E), and Vostok (78°8'S,106°52'E).
- 800,000-year record of Dust Mass Concentration
- 422,000-year record from Vostok
- Additional Dust records in ice cores are available from the World Data Center for Paleoclimatology (see microparticles).
Samples are covered and carried to a Class 100 clean room (less than 100 particles greater than 0.5 micrometers in diameter per cubic foot of air) and then rinsed with pure water and allowed to melt. The room is maintained at positive air pressure so that no air enters when the door is opened. Personnel wear a lab gown with a hood and shoe covering to minimize particles entering the room on clothing, body, or hair.
In a Coulter-type particle counter, melted ice is drawn through an opening small enough that only one particle can pass through at a time. Each particle causes a change in impedance across the opening, and the impedance change is proportional to the volume of the particle. For mass calculations, a particle density of around 2.5 g/cm3 is assumed (Petit et al., 1999; EPICA Community Members, et. al 2004).
In a laser particle counter, a beam of monochromatic light scans a controlled volume and the instrument electronically counts the number of pulses produced by the scattered light. In some instruments the shadows cast by absorbing particles are also counted. The strength of the pulse of reflected/scattered light provides information about particle size. Information from lengthwise and depthwise scanning also reveals information about particle shapes.
Temporal uncertainty of the EPICA 800,000-year series increases with core depth, but estimates indicate that it is usually less than 5% of the true age and is frequently much less than that. The most recent "EDC3" chronology (Parrenin et al., 2007) is based on a snow-accumulation and mechanical flow model combined with a set of independent age markers along the core, indicating either well-dated paleoclimatic records or insolation variations. See Parrenin et al. (2007) for more detail.
The Vostok time scale is based on the the "GT4" chronology, derived in a similar fashion to "EDC3" with age constraints at 110 thousand and at 390 thousand years ago which are assumed to match known events in marine sediments. See Petit et al. (1999) for more detail.
Insoluble dust accumulated in the Dome C ice core has fluctuated between virtually zero and almost 1.5 milligrams of dust per kilogram of ice over the last 800,000 years. Higher dust concentrations accompany glacial periods, which suggests some combination of decreased vegetation, increased aridity, and increased wind strength in high-latitude land areas of the Southern Hemisphere, which is the source of much of the dust according to studies of its mineral composition. (EPICA Community Members, 2004).
- EPICA Community Members, 2004. Eight glacial cycles from an Antarctic ice core. Nature 429: 623-628
- Petit J.R., Jouzel J., Raynaud D., Barkov N.I., Barnola J.M., et al. 1999, Climate and Atmospheric History of the Past 420,000 years from the Vostok Ice Core, Antarctica, Nature 399, pp.429-436.
- Parrenin, F., J.-M. Barnola, J. Beer, T. Blunier, E. Castellano, et al. 2007. The EDC3 chronology for the EPICA Dome C ice core. Climate of the Past 3, 485-497.
- Lambert, F., B. Delmonte, J.R. Petit, M. Bigler, P.R. Kaufmann, M.A. Hutterli, T.F. Stocker, U. Ruth, J.P. Steffensen and V. Maggi. 2008. Dust-climate couplings over the past 800,000 years from the EPICA Dome C ice core. Nature 452, 616-619, doi:10.1038/nature06763.
- Petit, J.R., et al., 2001, Vostok Ice Core Data for 420,000 Years, IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series #2001-076. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.
- Petit J.R., Jouzel J., Raynaud D., Barkov N.I., Barnola J.M., Basile I., Bender M., Chappellaz J., Davis J., Delaygue G., Delmotte M., Kotlyakov V.M., Legrand M., Lipenkov V., Lorius C., Pépin L., Ritz C., Saltzman E., Stievenard M., 1999, Climate and Atmospheric History of the Past 420,000 years from the Vostok Ice Core, Antarctica, Nature 399, 429-436.
Other Data Sets
- Instructions for the World Data Center material are given in the headers of the data files.
If accessing the data from this site: Please also cite: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy.
If citing material from this page only, cite as: 800,000-year Ice-Core Records of Aerosols, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy. http://cdiac.ess-dive.lbl.gov/ice_cores_aerosols.html.