Transcript WAIS Divide Ice Core Project Goals Science Projects & Principal Investigators Investigate the linkage between greenhouse gases and climate. Science Coordination Office: Taylor, Twickler Optical imaging.

WAIS Divide Ice Core Project
Goals
Science Projects & Principal Investigators
Investigate the linkage between greenhouse
gases and climate.
Science Coordination Office: Taylor, Twickler
Optical imaging of cores: McGwire
Electrical measurements: Taylor
Investigate the relationship of how the Antarctic
and Arctic responded to previous climate
changes.
Trace Chemistry: McConnell
Black Carbon: Edwards, McConnell
Improve our ability to predict how the West
Antarctic Ice Sheet (WAIS) will respond to
future climate change.
Annual layer dating: Taylor, McConnell, McGwire, Cole-Dia
WAIS Divide
Methane: Brook, Sowers
McMurdo
Investigate the biology of ancient ice.
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.
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
Methods
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.
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.
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
I think this is where my
tent is..
Field work
The field work started with a drill test in
Greenland in 2006. 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.
For more information please contact:
Ken Taylor, WAIS Divide Chief Scientist
Research Professor, Desert Research Institute, Reno, Nevada, USA
Email: [email protected] Website: http://waisdivide.unh.edu
2012
2006
The drill shelter, in 2006 and in 2012. The
high annual snowfall makes thick annual
layers, but quickly buries everything.
Tilting
tower
Winch
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.
Sharp cutters shave out a ring of ice.
An ice core sticks out from the bottom of the drill.
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 tilting tower is horizontal, which makes
is simpler to remove core from the drill.
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 OPP0440817 and OPP-0944348 to the Desert Research Institute, Nevada System of Higher Education,
and OPP-0944266 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
The University of
Wisconsin,
Madison is
responsible for
the drill design,
construction and
operations.
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.
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 science crew greatly appreciates the support it has received from NSF; and the hard work
of the many people in the 109th Air National Guard, science support and drilling communities
who made this project possible.
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 - CO2: WAIS Divide has recovered the most detailed and best
dated record of how atmospheric CO2 has changed over the last 23,000 years. This
record shows that major changes in CO2 occurred in steps, not as gradual
transitions, and that CO2 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 - CH4: WAIS Divide has also recovered the most detailed record of
how atmospheric CH4 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)
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 CO2 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).