Drilling of the ice core ReCap was supported by The Danish National Research Foundation, the American National Science Foundation, the German Alfred Wegener Institute and the European Union Horizon 2020 Research and Innovation Programme. The measurements of dust were supported by the EU funding ice2ice and Horizon 2020 - TIPES.
NOTE:
Researchers from the
section Physics of Ice,
Climate and Earth (PICE)
at the Niels Bohr Institute,
University of Copenhagen,
have succeeded in creating
a new method to study,
an otherwise dark period
in climate history.
Working with the
ice core ReCap,
drilled close
to the coast in
East Greenland,
Marius Simonsen
wondered why the
dust particles from
the interglacial period
- the warmer period
of time between
the ice ages -
were several times
bigger than the
dust particles
from the ice age.
SUMMARY:
Research led to
the invention
of a method
able to map the
advancement
of the glaciers
in cold periods,
and the melting
in warmer periods.
The results from
the new method,
can now be used
to compare the reaction
in the masses of ice,
to changes in the
atmospheric content
of greenhouse gasses
like CO2.
These data
are important
for the
climate models
we use to predict
sea level rise.
The new method
helps us by
putting constraints
on our knowledge
about he influence
of greenhouse
gasses on ice
melting and,
consequently,
on sea level.
The new method
can provide
new information
on how fast the
glaciers recede.
The results are
now published in
Nature Communications.
The end of the ice age,
where the ice glacier
is receding, is
well understood,
Marius Simonsen explains.
"But it is very difficult
to retrieve data
on the period
before the ice age.
The ice is an
extremely strong
natural force,
so it grinds away
everything
when advancing.
But with the new method,
we have data on the
advancement of the ice.
All of a sudden,
we have a link
to information
on how quickly
we enter an ice age,
in a way we never
used to have".
Helle Astrid Kjær,
Assistant professor
in PICE, says
the researchers
are planning
new drill sites in
North East Greenland
and Canada, to gather
more data on changes
of past glaciers.
"Perhaps,
with the new method,
we are able to
see how fast
the ice age came in
from the north
and moved south",
Helle Astrid Kjær says.
DETAILS:
Then PhD student,
Marius Simonsen,
examined dust
at select locations
on the coast
of East Greenland,
close to the
ice core drill site.
The larger particles
of dust caught in the ice,
come from East Greenland.
The smaller particles
of dust caught in the ice,
travel from Asia,
blown to Greenland
by dust storms.
So having bigger
dust particles
in the ice,
must mean
the presence
of bare land
close to the
ice core drill site.
Having small particles
in the ice, must mean
the land was covered
in ice.
The glacier ice
is composed
of annual layers,
like growth rings
in a tree, so the
distribution of
large and small
dust particles,
can be linked
to the advancement,
and melting, of the ice.
Marius Simonsen says:
"The glaciers receded
at the beginning
of the present interglacial,
just like they do today,
because of climate change.
The two scenarios
are not entirely
comparable,
because there was
much more
inland ice then,
than now,
by the coast
in East Greenland
where the ice core
is drilled.
Nevertheless,
the results
are very
interesting indeed,
when making
climate models,
because the models
must be tested
by comparison
to reality.
And in the
new method
we've acquired
an anchor point
in a period about
which not much
scientific
knowledge
existed".
The new method
requires bare land
in the vicinity
of the ice core
drill site,
so dust particles
can be found.
This was the case
during the last
interglacial, as the
temperature then,
approximately
115,000 years ago,
was up to
+8 degrees C.
warmer than today,
according to
a former study
from the
Niels Bohr Institute.
The new method
will most likely
be most usable in
North East
Greenland
and Canada.