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Geosciences Column: The best spots to hunt for ancient ice cores

Geosciences Column: The best spots to hunt for ancient ice cores

Where in the world can you find some of Earth’s oldest ice? That is the question a team of French and US scientists aimed to answer. They recently identified spots in East Antarctica that likely have the right conditions to harbor ice that formed 1.5 million years ago. Scientists hope that obtaining and analysing an undisturbed sample of ice this old will give them clues about Earth’s ancient climate.

The team published their findings in The Cryosphere, an open access journal of the European Geosciences Union (EGU).

Why study ancient ice?

When snow falls and covers an ice sheet, it forms a fluffy airy layer of frozen mass. Over time, this snowy layer is compacted into solid ice under the weight of new snowfall, trapping pockets of air, like amber trapping prehistoric insects. For today’s scientists, these air bubbles, some sealed off thousands to millions of years ago, are snapshots of what the Earth’s atmosphere looked like at the time these pockets were locked in ice. Researchers can tap into these bubbles to understand how the proportion of greenhouse gases in our atmosphere have changed throughout time.

As of now, the oldest ice archive available to scientists only goes back 800,000 years, according to the authors of the study. While pretty ancient, this ice record missed out on some major climate events in Earth’s recent history. Scientists are particularly interested in studying the time between 1.2 million years ago and 900,000 years ago, a period scientifically referred to as the mid-Pleistocene transition.

In the last few million years leading up to this transition, the Earth’s climate would experience a period of variation, from cold glacial periods to warmer periods, every 40,000 years. However, after the mid-Pleistocene transition, Earth’s climate cycle lengthened in time, with each period of variation occurring every 100,000 years.  

Currently, there isn’t a scientific consensus on the origin of this transition or what factors were involved. By examining old ice samples and studying the composition of the atmospheric gases present throughout this transition, scientist hope to paint a clearer picture of this influential time. “Locating a future 1.5 [million-year]-old ice drill site was identified as one of the main goals of the ice-core community,” wrote the authors of the study.  

The quest for old ice

Finding ice older than 800,000 years is difficult since the Earth’s deepest, oldest ice are the most at risk of melting due to the planet’s internal heat. Places where an ice sheet’s layers are very thick have an even greater risk of melting.

Mesh, bedrock dataset (Fretwell et al., 2013; Young et al., 2017) and basal melt rate (Passalacqua et al., 2017) used for the simulation. Credit: O. Passalacqua et al. 2018.

“If the ice thickness is too high the old ice at the bottom is getting so warm by geothermal heating that it is melted away,” said Hubertus Fischer, a climate physics researcher from the University of Bern in Switzerland not involved in the study, in an earlier EGU press release.

Last summer, a team of researchers from Princeton University announced that they had unearthed an ice core that dates back 2.7 million years, but the sample’s layers of ice aren’t in chronological order, with ice less than 800,000 years old intermingling with the older frozen strata. Rather than presenting a seamless record of Earth’s climate history, the core can only offer ‘climate snapshots.’

Finding the best of the rest

The authors of the recent The Cryosphere study used a series of criteria to guide their search for sites that likely could produce ice cores that are both old and undisturbed. They established that potential sites should of course contain ice as old as 1.5 million years, but also have a high enough resolution for scientists to study frequent changes in Earth’s climate.

Additionally, the researchers established that sites should not be prone to folding or wrinkling, as these kinds of disturbances can interfere with the order of ice layers.

Lastly, they noted that the bedrock on which the ice sheet sits should be higher than any nearby subglacial lakes, since the lake water could increase the risk of ice melt.

Magenta boxes A, B and C correspond to areas that could be considered as our best oldest-ice targets. Colored points locate possible drill sites. Credit: O. Passalacqua et al. 2018.

 

Using these criteria, the researchers evaluated one region of East Antarctica, the Dome C summit, which scientists in the past have considered a good candidate site for finding old ice. They ran three-dimensional ice flow simulations to locate parts of the region that are the most likely to contain ancient ice, based on their established parameters.

By narrowing down the list of eligible sites, the researchers were able to pinpoint regions just a few square kilometres in size where intact 1.5 million-year-old ice are very likely to be found, according to their models. Their results revealed that some promising areas are situated a little less than 40 kilometres southwest of the Dome C summit.

The researchers hope their new findings will bring scientists one step closer towards finding Earth’s ancient ice.

By Olivia Trani, EGU Communications Officer

June GeoRoundUp: the best of the Earth sciences from around the web

June GeoRoundUp: the best of the Earth sciences from around the web

Drawing inspiration from popular stories on our social media channels, as well as unique and quirky research news, this monthly column aims to bring you the best of the Earth and planetary sciences from around the web. 

Major story  

While May’s headlines may have been dominated by the Kilauea Volcano’s recent eruption in Hawaii, the science news world directed its attention to another volcanic event early this month. On June 3, Guatemala’s Volcán de Fuego erupted, sending plumes of volcanic ash several kilometres into the air. The volcano also unleashed an avalanche of hot gas and debris, otherwise known as pyroclastic flows, more than 10 kilometres down the volcano’s flanks onto the surrounding valley.

The Volcán de Fuego has been an active volcano since 2002, however, this latest event has been the volcano’s most violent eruption in more than four decades.

By 23 June, officials reported that the eruption has killed 110 people from surrounding villages, with hundreds more missing or injured.

Both Kilauea and Fuego gained international attention this year, but the two volcanoes exhibit very different behaviours by nature.

Kilauea is a shield volcano, with a relatively gradual slope and a highly fluid lava flow that can travel far distances compared to other volcanic archetypes. While the volcanic eruption’s lava, ash and haze present real threats to nearby communities, very few injuries have been reported.

“Lava flows rarely kill people,” said Paul Segall, a professor of geophysics at Stanford University, to the New York Times. “They typically move slow enough that you can walk out of the way.”

The Fuego volcano on the other hand is a stratovolcano, characterised by a cone-shaped peak built by layers of lava and ash. This type of volcano usually contains more viscous magma, meaning the hot liquid material has a sticky, thicker consistency. This type of fluid in volcanoes “clogs their plumbing and leads to dramatic explosions,” says Smithsonian Magazine.

Stratovolcanoes like Fuego also often release pyroclastic flows. These plumes can be a major threat to human health and make this kind of volcano particularly dangerous. “On its surface, a pyroclastic flow looks like a falling cloud of ash. But if you could peer into the cloud, you would find a really hot and fast-moving storm of solid rock,” reported PBS NewsHour.

Paul Rincon, a science editor for BBC News notes that pyroclastic flows can reach speeds of up to 700 kilometres per hour and are extremely hot, with temperatures between 200 to 700 degrees Celsius.

As of June 17, Guatemalan authorities have officially stopped looking for bodies and survivors. However, some local rescue workers have kept on with their search. 

What you might have missed

Meanwhile this month, in a vastly different part of the world, scientists have uncovered a wealth of new insight into Antarctica and how the region’s ice melts. Some of the discoveries made known are very foreboding while others more uplifting.

Let’s start with the bad news first. A study published this month in Nature revealed that Antarctica is melting faster than ever, and the continent’s rate of ice loss is only accelerating.

The report explains that before 2012 the Antarctic ice sheet steadily lost 76 billion tonnes of ice each year, contributing 0.2 milimetres to sea-level rise annually. However, since then, Antarctica’s rate of ice loss has increased threefold. For the last fives years the ice sheet has shed off 219 billions tonnes of ice each year. This ice loss now corresponds to a 0.6 milimetre contribution, making Antarctica one of the biggest sources of sea-level rise.

The largest iceberg ever recorded broke away from the Antarctic Peninsula in 2017. Pictured here is the iceberg’s western edge. (Credit Nathan Kurtz/NASA)

This record pace could have a devastating impact around the world, the researchers involved with the study say.

“The continent is now melting so fast, scientists say, that it will contribute six inches (15 centimeters) to sea-level rise by 2100,” reports the New York Times.

The articles continues: “’around Brooklyn you get flooding once a year or so, but if you raise sea level by 15 centimeters then that’s going to happen 20 times a year,’ said Andrew Shepherd, a professor of earth observation at the University of Leeds and the lead author of the study.”

On the other hand, one study published this month in Science offers a glimmer of hope, suggesting that a natural geologic process may help counteract some of the Earth’s sea level rise.

A team of researchers found evidence that, in response to losing ice mass, the ground underneath melting ice sheets naturally lifts up, and more substantially than scientists had previously believed. This process could help prevent further ice loss by land locking vulnerable ice sheets.

Scientists say that many ice sheets in the West Antarctic are at risk of collapsing, and furthermore contributing to sea level rise, because they are in direct contact with the ocean. The relatively warm seawater can melt these glaciers from underneath, making these giant frozen masses more at risk of losing a substantial amount of ice.

However, the new research on the West Antarctic Ice Sheet finds that as these ice masses lose weight, the ground underneath springs up, acting much like a memory-foam mattress.

“This adjustment of the land once the weight of the ice has been lifted is known as ‘glacial isostatic adjustment,’” says Carbon Brief. “It is usually thought to be a slow process, but the new data suggests the ground uplift beneath the [Amundsen Sea Embayment] area is occurring at an unprecedented rate of 41mm per year.”

A press release from Delft University of Technology in the Netherlands goes on to say that “the measured uplift rate is up to 4 times larger than expected based on the current ice melting rates.”

While this discovery offers a brighter view to the serious state of Earth’s melting ice, scientists still caution that this natural grounding process may be rendered useless in extreme cases climate change with extensive ice loss.

Links we liked 

The EGU story

For the first time, we gave participants at the annual EGU General Assembly the opportunity to offset the COemissions resulting from their travel to and from Vienna.

We are happy to report that, as a result of this initiative, we raised nearly 17,000 EUR for a carbon offsetting scheme. The Carbon Footprint project the EGU is donating to aims to reduce deforestation in Brazil and “is expected to avoid over 22 million tonnes of carbon dioxide equivalent greenhouse gas emissions over a 40 year period.”

Do you enjoy the EGU’s annual General Assembly but wish you could play a more active role in shaping the scientific programme? Now is your chance! Help shape the scientific programme of EGU 2019.

From now until 6 Sep 2018, you can suggest:

  • Sessions (with conveners and description),
  • Short Courses, or;
  • Modifications to the existing skeleton programme sessions

Plus from now until 18 January 2019, you can propose townhall meetings. It’s important to note that, for this year’s General Assembly, session proposals for Union Symposia and Great Debates are due by 15 August 2018

And don’t forget! To stay abreast of all the EGU’s events and activities, from highlighting papers published in our open access journals to providing news relating to EGU’s scientific divisions and meetings, including the General Assembly, subscribe to receive our monthly newsletter.

Imaggeo on Mondays: Arctic cottongrass in Svalbard

Imaggeo on Mondays: Arctic cottongrass in Svalbard

In the High Arctic, where vegetation is limited in height, cottongrass stands out as some of the tallest plant species around.

This photo shows a wispy white patch of Arctic cottongrass growing amongst other tundra vegetation in the Advent river floodplain of Adventdalen, a valley on the Norwegian archipelago island Svalbard.

Svalbard is of particular scientific interest as it is a relatively warm region for its high latitude. This is due to the North Atlantic Ocean, which transports heat from lower latitudes to Svalbard’s shores.

The photo was taken in September 2014, towards the end of the region’s growing season. In the background, you can see that the season’s first snow had already blanketed the valley’s neighboring mountain tops.

Cottongrass generally loves wet conditions and scientists sometimes even use this plant genus (Eriophorum) as an indicator of the ground’s fluctuating water level, especially in areas that begin to develop peat, an accumulation of more of less decomposed plant material in wet environments. The waters feeding this region’s wetland come from melted snow and ice travelling down the adjacent mountains and floodwater from the Advent river, which is primarily meltwater fed.

Arctic cottongrass also can exchange gases with their underground environment through their roots and even have been shown to alter the local carbon budget of regions where they grow. It is therefore a very important species to account for when studying permafrost carbon dynamics.

Gunnar Mallon, currently a teaching fellow at the University of Sheffield (UK), took this photo while on a fieldwork expedition together with Andy Hodson, a glaciology professor at the University Centre in Svalbard, for the LowPerm project.

The LowPerm project aimed to understand how nutrients are transported within permafrost landscapes in Norway and Russia and how that may affect the production of greenhouse gases, such as carbon dioxide (CO2) and methane (CH4). The study brought together scientists from the UK, Norway, Denmark and Russia and results from the extensive field and laboratory work are currently being analysed and made ready for publication.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: Science in the Arctic trenches

Imaggeo on Mondays: Science in the Arctic trenches

Pictured here are climate scientists processing ice core samples in the East Greenland Ice-core Project (EastGRIP) science trench 10 m under the surface of the Greenland ice cap.

The trenches of this ice core camp require minimum building materials, utilising giant inflatable balloons that are dug in and covered with snow. The snow is left to compact for a few days, thereafter leaving back an arch-shaped underground trench ideal for ice core processing activities.

At this site, an international research consortium of ten countries led by the Center for Ice and Climate at the University of Copenhagen is aiming to retrieve an ice core from the surface of the Northeast Greenland Ice Stream, a fast-moving ribbon of ice within the Greenland Ice Sheet (GIS), all the way to the bedrock (approx. 2500 m).

Contrary to previous ice coring sites from the ice divide of the GIS, the EastGRIP site is a very dynamic place with a surface velocity of 55 m/year. Ice streams are responsible for a significant amount of the mass loss from the GIS, however their properties and behaviour are currently poorly understood. Having a better understanding of the streams’ features will allow for more accurate estimates of how the GIS accumulates and loses ice under current conditions as well as in warmer climate scenarios.

In order to understand the behavior of the site better, scientists carry out a series of state-of-the-art measurements on the ice core. They examine the physical properties and grain structure of the ice, as well as palaeoclimatic parameters, such as water isotopic ratios, gas concentrations and impurities. This research is often run by novel analytical methods that were specially developed in-house by members of this project. This constitutes a massive effort in terms of ice core sampling and measuring, a large part of which takes place in the field.

In weather-protected trenches under the surface of the snow, scientists process the ice core, part of which is measured on site. The rest of the ice is flown out of camp and distributed to laboratories around the world. The trenches provide a stable temperature environment, a feature important for the quality of the ice core sample.

By the end of the 2017 field season, the drill had reached a depth of 893 m and operations for 2018 are currently well under way. It is possible to follow the camp’s daily activities at the field diaries section here.

By Vasileios Gkinis, Center for Ice and Climate at the University of Copenhagen

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.