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Goals Investigate the linkage between greenhouse gases and climate. Investigate the relationship of how the Antarctic and Arctic responded to previous.

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Presentation on theme: "Goals Investigate the linkage between greenhouse gases and climate. Investigate the relationship of how the Antarctic and Arctic responded to previous."— Presentation transcript:

1 Goals Investigate the linkage between greenhouse gases and climate. Investigate the relationship of how the Antarctic and Arctic responded to previous climate changes. Improve our ability to predict how the West Antarctic Ice Sheet (WAIS) will respond to future climate change. Investigate the biology of ancient ice. Methods We have collected and are analyzing a 3,405 m deep ice core that extends 68,000 years back in time. The site was selected because it is the best place on earth to obtain a record of how greenhouse gases have changed over the last 50,000 years. NSF has funded 48 individually proposed projects (see below) to make a wide variety of measurements on the gases, insoluble dust, soluble chemistry, and water that make up the ice core. Field work The field work started with a drill test in Greenland in The main hole was completed in December 2012 at a depth of 3,405 m. We left 50 m of ice between the bottom of the hole and the water saturated basal material because drilling into the basal material with a drill designed for ice coring would have contaminated the water saturated basal environment. In the 2012/2013 field season we will drill into the side of the existing borehole and collect ~ 250 m of additional ice core parallel to the existing hole, from depths of high scientific interest. In 2014 and future years, measurements will be made in the borehole. Science Projects & Principal Investigators Science Coordination Office: Taylor, Twickler Optical imaging of cores: McGwire Electrical measurements: Taylor Trace Chemistry: McConnell Black Carbon: Edwards, McConnell Annual layer dating: Taylor, McConnell, McGwire, Cole-Dia Methane: Brook, Sowers CO2: Brook, Mix Nitrogen, Oxygen & trace gases: Severinghaus, Saltzman, Aydin Chemistry & gases in firn: Bales Gases in firn and shallow ice: Brook, Sowers, White, Severinghaus, Battle, Saltzman, Aydin Chemistry: Cole-Dia, McConnell Particles and Chemistry: Kreutz, McConnell Beryllium 10: Welten, Caffee, Nishiizumi Site Selection: Conway, Waddington, Morse, Raymond Volcanics - Tephra: Dunbar Volcanics - Optical Borehole logging: Price, Bay, Talghader Biology in ice: Priscu, Foreman, Price Nitrate and Sulfate isotopes: Steig, Alexander, Cole-Dai, Thiemens Ice physical properties: Alley, Voigt, Cuffey, Reusch, Spencer Sonic logging – ice physical properties: Waddington, Peters, Anandakrishnan Televiewer logging – ice physical properties: Pettit, Obbard Ice sheet physical properties: Anandakrishnan, Peters Water isotopes: White, Steig, Cuffey Ice fabric - radar: Matsuoka Dust source areas: Kaplan Paleo-borehole thermometry: Clow, Alley, Cuffey Firn microstructure: Albert Drilling: Bentley, Twickler, Albert For more information please contact: Ken Taylor, WAIS Divide Chief Scientist Research Professor, Desert Research Institute, Reno, Nevada, USA Website: The majority of the science funding for this project has come from the Antarctic Glaciology program of the United States Antarctic program. Dr. Julie Palais is the manager of this program. This material is based on work supported by the National Science Foundation under awards OPP and OPP to the Desert Research Institute, Nevada System of Higher Education, and OPP to the University of New Hampshire. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation Location and age of the ice The location of the drill site was selected because it is on an ice flow divide. The ice flow (indicated by red flow lines in the logo) is such that the ice deep below the drill site fell as snow at the drill site. At locations off the divide the ice deep below the drill site fell at another location and then moved below the drill site. The location was also selected because it has a high annual snow fall rate. This makes the annual layers thick so we can obtain a high time resolution record. We have determined the age of the ice by counting the annual layers to an age of 28,000 years before present, at which time we are no longer confident we can identify all the annual layers. To determine the age of the ice older than 28,000 years we have used stratigraphic methods to determine that the oldest ice in the core is 68,000 years old. Why we drill ice A snow pit, with light shining through thin walls, shows the layers of previous snowfall. These layers contain a record of the environment when the snow fell. The layers contain: (1) insoluble material (dust, soot from biomass burning, volcanic tephra), (2) soluble material (sea salts, organic compounds, minerals), water (with varying isotopic composition), and atmospheric gases. The layers are compressed into ice when they are buried by more snow. The deeper the ice, the older it is. By examining deep ice, old ice, we can understand how previous changes in greenhouse gases influenced climate. This information is used to improve predictions of how the current human caused increases in greenhouse gas concentrations will influence our climate. The drill has a tilting tower. The drill sonde is raised and lowered in the borehole by a cable. It recovers up to 2.8 m of core each trip down the hole. Early Science Results As of October 2012, we are still making our first round of measurements on the core. Selected science highlights are listed below. Greenhouse gas - CO 2 : WAIS Divide has recovered the most detailed and best dated record of how atmospheric CO 2 has changed over the last 23,000 years. This record shows that major changes in CO 2 occurred in steps, not as gradual transitions, and that CO 2 increased at the same time as the world started to warm at the end of the last deglaciation. This information will be used to test and improve predictions of future climate change. Work is continuing to extend this record to beyond 60,000 years. (Ed Brook, Shaun Marcott; Oregon State University) Greenhouse gas - CH 4 : WAIS Divide has also recovered the most detailed record of how atmospheric CH 4 has changed over the last ~68,000 years. This record will be compared to similar records from Greenland, allowing investigation of the differences in carbon sources and sinks between the Northern and Southern hemispheres during periods of climate change. This information will be used to test and improve predictions of future climate change. (Ed Brook, Oregon State University; Todd Sowers, Pennsylvania State University) The length and quality of the cores is determined in the field. Most of the measurements are made in labs in the United States. The cores are archived at the National Ice Core Laboratory in Denver. The cores are cut and samples sent to the 26 different labs working on the project. The drill shelter, in 2006 and in The high annual snowfall makes thick annual layers, but quickly buries everything. An ice core sticks out from the bottom of the drill. WAIS Divide Ice Core Project I think this is where my tent is.. The University of Wisconsin, Madison is responsible for the drill design, construction and operations. Tilting tower Winch The science crew greatly appreciates the support it has received from NSF; and the hard work of the many people in the 109 th Air National Guard, science support and drilling communities who made this project possible. Temperature change during the last 1000 years: Changes in the surface temperature at WAIS Divide can be determined by measuring the change in the isotopic concentration of the snow fall and by directly observing the temperature distribution in the top 300 m of ice. These methods both indicate that the surface temperature at WAIS Divide has increased at a rate of 0.23°C/decade over the last 50 years. (Anais Orsi, Scripps Institution of Oceanography; Eric Steig, University of Washington). Temperature change over the last ~68,000 years: WAIS Divide has recovered the most detailed record of how atmospheric temperature has changed over the last ~68,000 years. The record, which is based on both isotope concentrations in the ice, and on borehole temperature measurements, shows that West Antarctica warmed more than previously thought at the end of the last glacial period. Sea ice changes that began to occur about 22,000 years ago probably explain the early warming at WAIS Divide, which preceded both Antarctica-wide warming and the CO 2 rise at about 18,000 years ago. This information sheds new light on the coupling of the ocean, the atmosphere, and greenhouse gases (Gary Clow, USGS; Eric Steig, TJ Fudge; University of Washington). The tilting tower is horizontal, which makes is simpler to remove core from the drill. Sharp cutters shave out a ring of ice. WAIS Divide McMurdo


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