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https://news.ku.dk/all_news/2023/07/pay-dirt-for-ice-core-scientists-in-east-greenland-as-they-reach-bedrock/

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* Pay dirt for ice core ...

31 July 2023

Pay dirt for ice core scientists in East Greenland as they reach
bedrock

* Geophysics
* Greenland
* Climate

Greenland ice sheet

An international research collaboration (EGRIP) headed by ice core
scientists from the University of Copenhagen has attained their goal
of drilling to the bottom of the ice sheet. It marks the first time
that this has been achieved in an ice stream, where vast amounts of
ice slide coastwards. The breakthrough could be critical for
understanding and projecting rising sea levels.

Scientists looking down into a hole in the snow For seven years, ice
core researchers have drilled into the ice sheet in Northeast
Greenland from trenches established under the snow-covered surface of
the ice sheet. Photo: EGRIP

With a sudden reward of mud at their feet, researchers at the EGRIP
research station had successfully made it through the 2670-meter ice
sheet last week after seven years of drilling. In doing so, the
research group met their ultimate goal of drilling all the way
through the ice and to the bedrock below.

"This is the first time that a deep ice core has been drilled through
an ice stream, so it will be extremely exciting to analyse the
material, which has much to tell us about how our planet's climate
has changed over the past 120,000 years. But we need to wrap up our
work here first," says Professor Dorthe Dahl-Jensen of the University
of Copenhagen's Niels Bohr Institute, who leads research at EGRIP.

The mud, which had not seen the light of day for roughly a million
years, was only briefly exposed to sunlight, as white light can
damage ice core material. Instead, the core was retrieved in red
light and immediately packed away, like a Christmas present that will
need to remain unopened until some special day down the road.

Mud on a boot The researchers literally got mud from under the ice
cap on their feet. Photo: Trever Popp, EGRIP

"Though it was tempting to take a closer look, we quickly sealed the
ice core, kept it frozen and sent it to Kangerlussuaq Airport, where
it is now waiting for a flight to Denmark," says Dorthe Dahl-Jensen.

Results could change climate models

Despite the quick packaging and send off, the drilling has already
delivered the scientists research "gold".

Facts about ice cores

Ice cores contain a wealth of information about past environments,
which can be extracted from the ice itself, from impurities in the
ice and from bubbles trapped in the ice which contain samples of
ancient atmospheres, along with their greenhouse gas contents.

With regards to ice core contents, Dorthe Dahl-Jensen has previously
stated:

"For example, we can see all of the major volcanic eruptions by
measuring the sulphate content in ice cores. We can also see how
mercury and metals made it into the air as a result of industrial
development. As far back as Roman times, we can clearly see that the
content of heavy metals in the atmosphere has increased."

The first ice cores were drilled exactly seven years ago, on July 21,
2016. The 2020 and 2021 fieldwork seasons were canceled due to COVID.

This is the first time that a deep ice core has been drilled through
an ice stream. Greenland's ice streams supply the sea's surrounding
it with nutrients that are important for fishing. Thus, the future of
ice streams is also of direct importance to Greenland.

"The results are exceptional. The ice stream flows like a river of
ice that tears itself free of the surrounding slow-flowing ice sheet.
We can see that the entire 2670-meter-thick mass of ice flows like a
block at a speed of 58 meters per year. This will change climate
models because it redefines our basic understanding of how ice
moves," explains Dorthe Dahl-Jensen, who continues:

"The block of ice floats on a layer of wet mud. It seems to act as a
kind of layer of quicksand that allows the ice block to flow
undisturbed across the bedrock. Near the bottom of the ice sheet, we
find rocks and sand embedded in the ice. The measurements also show
that the ice is melting at the bottom," she says.

Towards the base, the ice is more than 120,000 years old and dates
back to the last interglacial period, a time when the atmospheric
temperature above Greenland was 5degC warmer than today.

Last drill got stuck

The last ice core was drilled on July 21, 2023. These final 4 meters
of ice were drilled using a rock coring system due to the presence of
pebbles in the ice.

Chief ice core driller Steffen Bo Hansen of the Niels Bohr Institute
was on hand when the breakthrough took place:

"The rock drill became stuck at the bottom and we feared that we
would lose both the last core and drill itself. Loosening the drill
was tough because it got stuck in the wet mud at the bottom.
Fortunately, we succeeded. We have now successfully drilled through
the ice stream, and it was amazing to find mud beneath the ice," he
says.

A 2670-meter-long account of Earth's climate

All in all, the ice core is a 2670-meter-long record that tells of
how our planet's climate has changed over the past 120,000 years. It
will be analyzed in dozens of laboratories around the world.

Due to the ice core's outstanding quality, the scientists expect to
be able to document the climate surrounding the ice during both the
warmer and colder periods of the 11,700 years since the last ice age,
as well as the anthropogenic changes caused by human development.

Scientists holding the last ice core The last ice core contained rock
and mud from the bottom 2670 meters below the ice. Photo Sepp
Kipfstuhl, EGRIP

Analyses of the last ice cores will begin in fall, when the research
group returns to Copenhagen. The EGRIP ice core is stored in the
Danish ice core repository in the Copenhagen suburb Brondby together
with most of the deep Greenland ice cores. Samples from the ice cores
drilled the previous years have been analyzed in more than 30
laboratories and the first 53 papers have been published.

Facts about the EGRIP camp, new technology and innovation.

The EGRIP camp is mobile. The main building, "The Dome", is on skis,
while the rest of the equipment and infrastructure is on sledges.
This allows the entire camp to be removed and towed by tracked
vehicles to new drilling sites on the Greenland Ice Sheet.

The scientists work in trenches beneath the snowy surface of the ice
sheet Photo: EGRIP

A drill trench and science trench were constructed beneath the snow
surface by inflating balloons with a diameter of five meters and a
length of 45 meters in seven-meter-deep trenches dug into the snow.
Snow was then blown over the tops of the balloons. After a few days,
the balloons were deflated and removed, after which the trenches were
ready for drill operations and ice core analyses.

Ice core scientists adjusting the ice drill Photo: Dorthe
Dahl-Jensen, EGRIP

A new electronic navigation package in the Danish made drill made it
possible for drillers to control the inclination of the ice core
drill and make future replicate coring in the same bore hole
possible.

EGRIP camp in sun and windy snow Photo: EGRIP

A key to understanding rising sea levels

The loss of ice from Greenland's ice sheet is a major contributor to
rising sea levels and is expected to increase as temperatures over
Greenland edge ever upwards. Half of this ice loss comes from
Greenland's ice streams, whose behavior is still not well understood.

Thus, knowledge of how Greenland's ice streams move is a key to
understanding how sea levels will rise in the future and will serve
to improve the accuracy of projections.

"I'm thrilled about the success. I've followed the flow of ice by
measuring the borehole's shape over the years using a borehole
logger. The fact that the ice is not dislodged, but slides as a block
over mud, will improve future sea level projections using
recalibrated models," says Dorthe Dahl-Jensen.

About the Study

EGRIP is an international project and includes participants from 12
nations. The contributing nations are Denmark, the United States,
Germany, Japan, Norway, Switzerland, China, Canada, France, South
Korea, the United Kingdom and Sweden.

Logistics are carried out by the University of Copenhagen and the US
National Science Foundation. All of the nations have participated in
fieldwork and ice core drilling. 40% of the more than 600 field
participants have been young scientists trained in EGRIP's
international research environment.

Thus far, samples from EGRIP ice cores have been analysed in more
than 30 laboratories and an initial 53 articles have been published (
https://eastgrip.org/Publications.html).

Denmark is EGRIP's largest partner, accounting for 55% of the
project's budget. The project is supported by the AP Moller
Foundation, the Villum Foundation and the University of Copenhagen.

Information on the project and field work can be found on the EGRIP
homepage and the publications here.EGRIP logo

Contact

Dorthe Dahl-Jensen
Professor
Niels Bohr Institute
University of Copenhagen
ddj@nbi.ku.dk
Telephone (EGRIP): +45 77 34 44
Whatsapp: +45 22 89 45 37

Jorgen Peder Steffensen
Professor
Niels Bohr Institute
University of Copenhagen
jps@nbi.ku.dk
Mobile +45 2035 1558
Phone in Greenland: +299 52 41 25

Steffen Bo Hansen
Chief driller
Niels Bohr Institute
University of Copenhagen
sbh@nbi.ku.dk
Mobile +45 2875 0614

Kristian Bjorn-Hansen
Journalist and press contact
The Faculty of Natural and Life Sciences
University of Copenhagen
kbh@science.ku.dk
+ 45 93 51 60 02

Topics

* Geophysics
* Greenland
* Climate