Scientists scramble to harvest ice cores as glaciers melt

The vanishing climate archives

Scientists scramble to harvest ice cores as glaciers melt

Ice provides historical records about climate and shows the impact humanity has had. But many glaciers are now melting, prompting renewed urgency among scientists.

Video by Riccardo Selvatico, National Research Council of Italy and Ca' Foscari University of Venice.

Scientists are racing to collect ice cores – along with long-frozen records they hold of climate cycles – as global warming melts glaciers and ice sheets. Some say they are running out of time. And, in some cases, it’s already too late.

Late last year, German-born chemist Margit Schwikowski and a team of international scientists attempted to gather ice cores from the Grand Combin glacier, high on the Swiss-Italian border, for a United Nations-backed climate monitoring effort.

In 2018, they had scouted the site by helicopter and drilled a shallow test core. The core was in good shape, said Schwikowski: It had well-preserved atmospheric gases and chemical evidence of past climates, and ground-penetrating radar showed a deep glacier. Not all glaciers in the Alps preserve both summer and winter snowfall; if all went as planned, these cores would have been the oldest to date that did, she said.

Scientists prepare to collect ice cores from the Colle Gnifetti glacier in the Alps. June 2021. Photo courtesy of Enrico Costa for Ca’ Foscari University of Venice / REUTERS.

But in the two years it took for the scientists to return with a full drilling set-up, some of the information that had been trapped in the ice had vanished. Freeze-thaw cycles had created icy layers and meltwater pools throughout the glacier, what another team member described as a water-laden sponge, rendering the core useless for basic climate science.

The sudden deterioration “tells us exactly how sensitive these glaciers are,” said Schwikowski, head of the analytical chemistry group at the Paul Scherrer Institute in Villigen, Switzerland. “We were just two years too late.”

Extracting ice cores

The U.S. Ice Drilling Program, a federally funded organization established by the National Science Foundation, recommends manual drills to obtain shallow ice cores and motor-powered drills for greater depths.

DEEP SAMPLES

Sheave

Specialized drills suspended on cables are typically used for depths greater than 40 meters.

The cable

Holds the drill’s barrel and conducts power to the drill head, which is lowered into the borehole.

SHALLOW SAMPLES

Samples

A manually-operated drill is commonly used to collect ice cores from the top 20 to 30 meters of a glacier or ice sheet.

The ice cores are found inside the inner barrel, which spins to cut the ice.

Inner barrel

Ice core

Control

box

Anti-torque

system

Drilling

motor

Winch

Sonde

The part of the drill that goes down the borehole, the sonde contains a cutter head and a barrel which collects the core.

Drill head

Metal

shell

Drill head

More than

300 meters deep

For deeper drilling, fluids are injected through the sonde to stabilize the temperature and prevent the borehole from collapsing.

Cutting

blades

Heating

ring

Electromechanical

drill head

Electrothermal

drill head

This spins inside the sonde to cut cores from the glacier, it has 3 or 4 adjustable steel cutting blades.

This uses a heating element covered by a metal shell to melt a ring of ice to cut a cylindrical sample. This method is used for “warm ice” naturally frozen above -10° C.

The mission on Grand Combin underscores the major challenge scientists face today in collecting ice cores: Some glaciers are disappearing faster than expected. The realization is prompting renewed urgency, causing those who specialize in harvesting ice cores to accelerate missions, rethink where to target next, and expand storage capacity.

Almost all of the world’s glaciers are shrinking, according to the United Nations. In its most comprehensive climate report to date, published in August, the UN concluded that “human influence is very likely the main driver of the near-universal retreat of glaciers globally since the 1990s.” The report also said that without immediate, large-scale action, the average global temperature will reach or exceed 1.5 degrees Celsius above the preindustrial temperature average within 20 years.

The pace at which glaciers are losing mass is also increasing. A study published in April in the science journal Nature, found glaciers lost 227 gigatons of ice annually from 2000 to 2004, but that increased to an average of 298 gigatons a year after 2015.

Melting ice

Glaciers have lost 298 gigatons of ice a year since 2015, a study found, which equates to around 0.8 gigatons per day on average. This amount of ice would fill New York City’s Central Park and stand 273 meters (896 feet) high.

BRONX

QUEENS

Central Park

273m

Daily melt

Average amount of ice lost daily

MANHATTAN

About 10% of the land area on earth is currently covered with glacial ice, according to the National Snow and Ice Data Center in Boulder, Colorado. If a glacier is melting and no longer accumulating snow, it means it also isn’t capturing atmospheric gases from today for scientists to study in the future.

Alps’ retreating glaciers

Glaciers in the Alps have been shrinking for decades, according to a database compiled by the Global Land Ice Measurements from Space (GLIMS), an international project to map the world’s glaciers. The Corbassiere Glacier shrank by 30% between 1850-2015.

SWITZERLAND

In blue, extent of glaciers in September 1850

Corbassiere

Glacier (1850)

Grand Combin

Monte Rosa

Matterhorn

In red, extent of glaciers as of August 2015

ITALY

Aosta

Two years ago, the south peak of Sweden’s Kebnekaise mountain lost its designation as the country’s highest point after a third of its summit glacier melted.

For Schwikowski, the disappearance of glaciers isn’t just a professional blow; it’s an emotional hit, too. “The mountains look different without them, barren,” she said. In the Alps, the mountains without glaciers are “absolutely frightening.”

How ice reveals climate records

Scientists measure isotopes trapped in ice cores. Those atomic variations within water molecules are like a snapshot of the atmosphere’s composition at the time they were frozen.

Water molecules are composed of two atoms of hydrogen and one atom of oxygen.

Hydrogen atoms occasionally have neutrons in the nucleus and in those instances are called hydrogen isotopes.

PROTIUM

DEUTERIUM

TRITIUM

One proton

and one neutron

One proton

and two neutrons

One of these isotopes, deuterium, is found in higher quantities when temperatures are warmer. The amount of deuterium in an ice sample can be used as a proxy for temperature.

WARMER WEATHER

COLDER WEATHER

The European Project for Ice Coring in Antarctica (EPICA), a program developed in collaboration with the European Commission, conducted deuterium isotope tests in thousands of ice cores to reconstruct climate records from the last 800,000 years.

An example of data collected in ice cores

Here are some key events from the last 800 millennia, based on the findings of the EPICA. The higher the concentration of CO2 in the atmosphere, the higher the earth’s temperatures are. In general, higher temperatures mean more isotopes in the ice.

← years ago →

* Deuterium readings per mille vs. standard mean ocean water (SMOW), a standard used for isotope analysis

10
years ago

800,000 years ago, the atmosphere had about 200 parts per million (ppm) of carbon dioxide (CO2). At this time, Antarctic temperatures were around 9 degrees below what the average has been over the past nearly 10,000 years.

Over the next 300,000 years temperatures and CO2 rise and fall, oscillating between glacial states and warmer states in cycles that lasted for around 100,000 years.

Around 300,000 years ago, modern humans known as Homo sapiens appeared.

For the next several hundred thousand years the same trend of warm periods followed by glacial ages continued, until the turn of the 20th century.

The last century reveals a sharp increase in CO2. The last point on the graphic is 368 ppm in 2001, the highest level of CO2 in the last 800 millennia and well above the previous maximum of 298 ppm more than 300,000 years ago.

‘COMPLETE SHOCK’

Last September, Schwikowski stood bundled in snow gear as wet cylinders of ice were winched out of the boreholes on Grand Combin. The wetness surprised her, she said. Frigid meltwater drained from ice core pieces that should have been solid. And the core, which should have been translucent, had sections that were perfectly clear.

Ice cores like those from Grand Combin have helped scientists illustrate humanity’s impact on earth’s climate by providing a record of greenhouse gases dating back well before industrialization. The ice preserves tiny air bubbles – direct evidence of past atmospheres. Ice also captures air pollutants, pollen and other temperature and precipitation measures in a single archive, all on the same time scale, sometimes at the resolution of individual seasons.

What’s in ice cores?

All ice cores are unique in some way. Some are crystal clear, others are opaque with irregular or darker layers. Here are some of the most common characteristics of ice cores.

Cores are typically 5 to 13 centimeters in diameter, depending on the drill

Visible marks

In some cores, the horizontal layers are easily visible with the naked eye. The crystalline cores offer clues about the seasons: the winter layers appear clearer while the summer layers tends to be more opaque.

Winter

Summer

Each core is sliced in parallel sections so it can provide material for multiple research studies.

Chemistry

Storage

Isotopes

Bubbles

When ice sheets form, they trap samples of the atmosphere in small bubbles, making them a window into the past for researchers.

Air trapped

Volcanic activity

In some cores, dark layers can be seen due to volcanic ash precipitation. This can also be compared with other geological records and verify the age of the ice.

Ash trapped

The deeper the ice, the more compact it becomes , making it harder for scientists to determine its age. Scientists use several methods to date the ice, including analyzing the chemical composition and electrical conductivity of the ice.

Higher

compression

Melting

unit

Current

inducer

Horizontal

saw

Slicing and documenting

Electrical conductivity

Chemistry

Each core is photographed and documented. Later, horizontal saws cut the ice cores into thin cross sections for different studies.

Electric currents are passed through the cores looking for variations in conductivity. The concentration of some elements is linked to the depth of the ice, therefore indicating its age.

Readings of chemicals present in the cores can help verify the age of the ice. Sea salt, for example, accumulates in cycles linked to the seasons.

Another member of the Grand Combin expedition, Italian climate scientist Carlo Barbante, said the speed at which the ice on the Alpine massif had melted in the last few years was “much higher than it was before.” Finding the wet cores was a “complete shock,” he said.

As a result, Barbante and other scientists - including Schwikowski - sped up plans to extract a core from the Colle Gnifetti glacier on the summit of the Alps’ Monte Rosa, a few hundred meters higher than Grand Combin. In June, several months earlier than originally scheduled, they launched. The two cores they drilled were of good quality, Barbante said.

Margit Schwikowski is pictured as scientists from the Ice Memory Project drill in the Monte Rosa massif in the Alps. June 2021. Photo courtesy of Enrico Costa for Ca’ Foscari University of Venice / REUTERS.

Barbante said he is also hoping to organize a trip to Mount Kilimanjaro, Africa’s highest mountain and the only possible ice core site left on the continent, next year or the year after. One study cited in the recent UN report calculated that present-day warming has already set in motion melting that will eliminate all glaciers on the mountain by 2060.

A 2009 discovery by American scientist Douglas Hardy of the mummified remains of a 19th century pig on one of the highest points of the mountain’s glaciers suggests some of the climate history the scientists are hoping to retrieve is already gone. “The implication of that is that we’ve lost [the] last 200 years’ worth of recorded time,” said Hardy.

Glaciers on Mount Kilimanjaro

Satellite images from the European Space Agency show how ice on Africa’s highest mountain has shrunk compared with three years earlier.

Satellite image by Sentinel-2. August 2018 / August 2021. Glaciers data from GLIMS.

Barbante and Schwikowski are part of a scientist-led group called Ice Memory that is trying to build an archive of ice cores from glaciers around the world. Ice Memory is endorsed by the UN’s main cultural agency, the United Nations Educational, Scientific and Cultural Organization (UNESCO).

So far they have drilled in Europe, Bolivia and Russia. The cores are temporarily being stored in Europe, but the plan is to ship them to Antarctica for long-term storage because the site wouldn’t depend on power, which could suffer an outage.

“A hundred years from now, when the Alpine glaciers will be completely disappeared, we will have the samples” for the future generations of scientists, said Barbante.

Where do ice cores come from?

Below are some of the drilling sites documented by the U.S. National Oceanic and Atmospheric Administration (NOAA).

DRILLING SITES

Fewer

Dunde

East Rongbuk

Belukha

El’gygytgyn crater

Siberia

Fedchenko

ASIA

Windy Dome

Mt. Hunter

Arctic

Ocean

Eclipse Icefield

Lomonosovfonna

Prince of Wales

Scarisoara

Renland

Beartooth Plateau

EUROPE

Fremont glacier

Col du Dome

NORTH

AMERICA

AFRICA

Greenland

This Danish territory in the Arctic provides approximately one third of all ice cores for study in the world.

Quelccaya ice cap

AFRICA

Kilimanjaro

SOUTH

AMERICA

South

Atlantic Ocean

Illimani

James Ross island

Huascaran

Dome Fuji

Gomez

Ferrigno

Dronning Maud Land

South

Pacific Ocean

ANTARCTICA

ITASA 00-5

Vostok

Concordia station

Deepest ice core

Law Dome

A collaborative ice-drilling project between Russia, the United States and France at the Vostok station yielded the deepest ice core ever recovered, reaching a depth of 3,623 meters

Australia

Grasberg

EXPANDING ICE STORAGE

Beyond greenhouse gases, scientists say they may also be able to use ice cores to study the DNA of ancient bacteria and viruses that could reemerge as the world warms. Frozen insects and plant pollen could also reveal histories of the world’s forests and their fire cycles.

Another team of scientists, whose findings were published in July in scientific journal Microbiome, found viruses nearly 15,000 years old in two ice core samples taken from the Tibetan Plateau in China. The findings identified genetic codes for 33 viruses, at least 28 of which were new to scientists.

That team of scientists included U.S.-based ice core paleoclimatologists Lonnie Thompson and Ellen Mosley-Thompson, who are husband and wife.

A 491,000-year-old ice sample taken from a depth of 2,874 m at the Concordia research station in Antarctica. This core extracted in Nov. 2002 was part of the samples obtained by the European Project for Ice Coring in Antarctica | Photo by L. Augustin / LGGE, REUTERS

Lonnie Thompson said the speed at which ice is disappearing has driven plans to expand his ice core storage facilities at Ohio State University, which he began fundraising for last year. He hopes to raise $7 million. So far he has raised about $475,000 through donations and pledges, according to the school’s Byrd Polar and Climate Research Center. The renovation will double the facility’s storage capacity to more than 13,550 meters of ice cores.

Some of the cores Thompson and his team have collected are the only remaining ice from some glaciers. Two of the six ice core sites on Kilimanjaro in Africa that his team drilled back in 2000 have disappeared. So have sites they drilled in 2010 in Papua, Indonesia. Others will likely be gone within 50 years, said Thompson.

In some of the cases, lakes formed on the glaciers’ surfaces as the ice melted, a red flag that indicated melting could be faster than models previously predicted. He said it was a wakeup call that cores needed to be harvested as soon as possible.

“Ice has a wonderful archive of not only the climate, but also the forcings of climate,” or major causes of climate change, Thompson said. “Those histories are at risk as the earth warms and the glaciers retreat.”

CORRECTION:

A previous version of the chart titled “An example of data collected in ice cores” inaccurately plotted CO2 and deuterium data on the X-axis resulting in a misleading timeline of events. The X-axis and accompanying captions and annotations have been corrected.

Reporting

Cassandra Garrison and Clare Baldwin

Graphics

Marco Hernandez

Editing

Simon Scarr, Katy Daigle and Cassell Bryan-Low

Sources

National Research Council of Italy; Ca’ Foscari University of Venice; U.S. Ice Drilling Program (IDP); Global Land Ice Measurements from Space ( GLIMS ); U.S. National Science Foundation Ice Core Facility (NSF-ICF); U.S. National Oceanic and Atmospheric Administration (NOAA); European Project for Ice Coring in Antarctica (EPICA); Carbon Dioxide Information Analysis Center (CDIAC); European Space Agency (ESA); Lucas Borges da Silva, University of Bern.