GeoLog

EGU Journals

Geosciences Column: The hunt for Antarctica’s oldest time capsule

Geosciences Column: The hunt for Antarctica’s oldest time capsule

The thick packs of ice that pepper high peak of the world’s mountains and stretch far across the poles make an unusual time capsule. As it forms, air bubbles are trapped in the ice, allowing scientists to peer into the composition of the Earth’s atmosphere long ago. Today’s Geosciences Column is brought to you by PhD researcher Ruth Amey, who writes about recently published research which reveals how a team of scientists might have found the oldest ice yet, which has important implications for our understanding of how Earth’s environment has changed over time.

Ice cores give us a slice through the past. By analysing the composition of ice and gas bubbles trapped within it, we can find out information about temperature, atmospheric conditions, deposition and even the magnetic field strength of the past.

This helps us to understand past conditions on the Earth, but currently the longest record is ~800,000 years (800 kyrs) old. One phenomenon scientists hope to understand better is a change in glaciation cycles. During the Mid-Pleistocene Transition, glaciation cycles changed from 40,000 year cycles related to the obliquity periodicity of the Earth’s orbit to longer, stronger 100,000 year cycles. Scientists of the ice-core community have their eyes on finding out why this change happened, and for this they need data from the onset of the change, between 1250 and 700 kyrs ago.

Which means we need much, much older ice.

A new study, published in EGU’s open access journal The Cryosphere has pinned down two locations where they think the base of Antarica’s ice sheet is significantly older. In fact they believe the ice could be as old as 1.5 million years, which would extend the current ice core record by ~700,000 years: nearly doubling it.

A Treasure hunt – using airborne radar and some simple models

The group, led by Frederic Parrenin at University of Grenoble Alpes, France, went on the hunt for the oldest ice East Antarctica could give them. The survival of ice is an interplay between many factors: the ice acts a little bit like a conveyor belt, being fed by accumulation, with the oldest information lost off the end by basal melting. This means areas of thinner ice, where there is less basal heating, often has a higher likelihood of the old, information-rich ice surviving.

Figure 2: A cross-section of ice in East Antarctica, from surface to bedrock, with colour bar showing the modelled ice age. The model identifies two patches of ice older than 1.5 Myr (shown in white): North Patch and Little Dome D Patch. Adapted from Figure 3 of Parrenin et al 2017.

Airborne radar can ‘see’ into the top three-quarters of the East Antarctica ice sheet. By identifying reflections within it, isochrones of ice of the same age can be traced. Parrenin’s group exploited an area in East Antarctica known as ‘Dome C’ with rich record of radar investigations. Using information derived from the radar, they then created a mathematical model, which balanced accumulation rate, heat flow and melting to give a simple 1-D ice flow model. This helps locate areas of accumulation and melting, which gives an indication of where ice might be the oldest, beyond the sight of the airborne radar. A nearby ice-core, EDC, also provided corroboration of their model.

X Marks the Spot

The team located two sites where they believe the ice to be older than 1.5 million years old, named Little Dome C and North Patch. And fortunately these sites are within a few tens of kilometres from the Concordia research facility, meaning drilling them is a real possibility.

This ancient ice could give vital insight into what happened in the Mid-Pleistocene Transition. What caused the new glaciation cycle onset? Was it a change in sea ice extent? A change in atmospheric dust? Decrease in carbon dioxide concentrations? Changes in the Earth’s orbit? The answers may well be locked in the ice.

By Ruth Amey, Postgraduate Researcher at the University of Leeds

 

References and Resources

Parrenin, F., Cavitte, M. G. P., Blankenship, D. D., Chappellaz, J., Fischer, H., Gagliardini, O., Masson-Delmotte, V., Passalacqua, O., Ritz, C., Roberts, J., Siegert, M. J., and Young, D. A.: Is there 1.5-million-year-old ice near Dome C, Antarctica?, The Cryosphere, 11, 2427-2437, https://doi.org/10.5194/tc-11-2427-2017, 2017

Berger, A., Li, X. S., and Loutre, M. F.: Modelling northern hemisphere ice volume over the last 3 Ma, Quaternary Sci. Rev., 18, 1–11, https://doi.org/10.1016/S0277-3791(98)00033-X, 1999

Imbrie, J. Z., Imbrie-Moore, A., and Lisiecki, L. E.: A phase-space model for Pleistocene ice volume, Earth Planet. Sc. Lett., 307, 94–102, https://doi.org/10.1016/j.epsl.2011.04.018, 2011

Jean Jouzel, Valérie Masson-Delmotte, Deep ice cores: the need for going back in time, In Quaternary Science Reviews, Volume 29, Issues 27–28, Pages 3683-3689, ISSN 0277-3791, https://doi.org/10.1016/j.quascirev.2010.10.002, 2010

Martínez-Garcia, A., Rosell-Melé, A., Jaccard, S. L., Geibert, W., Sigman, D. M., and Haug, G. H.: Southern Ocean dust-climate coupling over the past four million years, Nature, 476, 312–315, doi:10.1038/nature10310, 2011

Tziperman, E., and H. Gildor, On the mid-Pleistocene transition to 100-kyr glacial cycles and the asymmetry between glaciation and deglaciation times, Paleoceanography, 18(1), 1001, doi:10.1029/2001PA000627, 2003

Wessel, P. and W. H. F. Smith, Free software helps map and display data, EOS Trans. AGU, 72, 441, 1991

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

May 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

In the last couple of weeks of May, the news world was abuzz with the possibility of Donald Trump withdrawing from the Paris Agreement. Though the announcement actually came on June 1st, we’ve chosen to feature it in this round-up as it’s so timely and has dominated headlines throughout May and June.

In withdrawing from the agreement, the United States becomes only one of three countries in rejecting the accord, as this map shows. The implications of the U.S joining Syria and Nicaragua (though, to be clear, their reasons for not signing are hugely different to those which have motivated the U.S withdrawal) in dismissing the landmark agreement have been widely covered in the media.

President Trump’s announcement has drawn widespread condemnation across the financial, political and environmental sectors. Elon Musk, Tesla and SpaceX CEO, was one of many in the business sector to express their criticism of the President’s decision. In response to the announcement, Musk tweeted he was standing down from his duties as adviser to a number of White House councils. While in early May, thirty business CEOs  wrote an open letter published in the Wall Street Journal to express their “strong support for the U.S. remaining in the Paris Climate Agreement.”

In a defiant move, U.S. States (including California, New York and Vermont), cities and business plan to come together to continue to work towards meeting the targets and plans set out by the Paris Agreement. The group, coordinated by former New York City mayor Mark Bloomberg, aims to negotiate with the United Nations to have its contributions accepted to the Agreement alongside those of signatory nations.

“We’re going to do everything America would have done if it had stayed committed,” Bloomberg, said in an interview.

Scientist and learned societies have also been vocal in expressing their criticism of the White House decision. Both Nature and Science collected reactions from researchers around the globe. The EGU, as well as the American Geophysical Union, and many in the broader research community oppose the U.S. President’s decision.

“The EGU is committed to supporting the integrity of its scientific community and the science that it undertakes,” said the EGU’s President, Jonathan Bamber.

For an in-depth round-up of the global reaction take a look at this resource.

What you might have missed

This month’s links you might have missed take us on a journey through the Earth. Let’s start deep in the planet’s interior.

The core generates the Earth’s magnetic field. Periodically, the magnetic field reverses, but what caused it to do so? Well, there are several, competing, ideas which might explain why. Recently, one of them gained a bit more traction. By studying the seismic signals from powerful earthquakes, researchers at the University of Oxford found that regions on top of the Earth’s core sometimes behave like a giant lava lamp. It turns out that blobs of rock periodically rise and fall deep inside our planet. This could affect the magnetic field and cause it to flip.

Meanwhile, at the planet’s surface, the Earth’s outer solid layer (the crust) and upper layer of the molten mantle,  are broken up into a jigsaw of moving plates which pull apart and collide, generating earthquakes, driving volcanic eruptions and raising mountains. But the jury is still out as to when and how plate tectonics started. The Earth is so efficient at recycling and generating new crustal material, through plate tectonics, that only a limited record of very old rocks remains making it very hard to decipher the mystery. A recently published article explores what we know and what yet remains to be discovered when it comes to plate tectonics.

Tectonic plate boundaries. By Jose F. Vigil. USGS [Public domain], distributed by Wikimedia Commons.

Oil, gas, water, metal ores: these are the resources that spring to mind when thinking of commodities which fuel our daily lives. However, there are many others we use regularly, far more often than we realise or care to admit, but which we take for granted. Sand is one of them. In the industrial world it is know as ‘aggregate’ and it is the second most exploited natural resource after water. It is running out. A 2014 United Nations Environment Programme report highlighted that the “mining of sand and gravel greatly exceeds natural renewal rates”.

Links we liked

  • Earth Art takes a whole new meaning when viewed from space. This collection of photographs of natural parks as seen from above is pretty special.
  • This round-up is usually reserved for non-EGU related news stories, but given these interviews with female geoscientists featured in our second most popular tweet of the month, it is definitely worth a share: Conversations on being a women in geoscience – perspectives on what being a female in the Earth sciences.
  • We’ve shared these previously, but they are so great, we thought we’d highlight them again! Jill Pelto, a scientist studying the Antarctic Ice Sheet and an artist, uses data in her watercolous to communicate information about extreme environmental issues to a broad audience.

The EGU story

Temperatures in the Arctic are increasing twice as fast as in the rest of the globe, while the Antarctic is warming at a much slower rate. A new study published in Earth System Dynamics, an EGU open access journal, shows that land height could be a “game changer” when it comes to explaining why temperatures are rising at such different rates in the two regions. Read the full press release for all the details, or check out the brief explainer video, which you can also watch on our YouTube channel.

 

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.

All you ever wanted to know about EGU publications

All you ever wanted to know about EGU publications

Did you know that, the EGU, through Copernicus Publications, publishes 17 peer-reviewed open-access journals? The journals cover a range of topics within the Earth, planetary and space sciences: with publications spanning the cryospheric sciences, soil system sciences, through to non-linear processes in geophysics, there is something for everyone. Whatever your area of research, chances are you’ll be represented within the range of EGU publications!

Better still, the EGU is a signatory of the Berlin Declaration. This means we believe that scientific literature should be publicly available and free of charge. Anyone wishing to read, download, copy, distribute, search or print research findings is able to do so without encountering any financial, legal or technical barriers. Authors of research articles are fully protected, too! They retain full copyright for their work via the Creative Commons Attribution License, which requires that full credit for any distribution of the research is given and any changes made to figures and or/data is highlighted, too.

Most EGU Publications also extend the traditional peer-review process by applying the Interactive Public Peer Review system. This means that a manuscript is subjected to two stages of review. The figure below helps to illustrate the process.

Two-stage public peer review as practised in the scientific journal Climate of the Past (CP) and its discussion forum Climate of the Past Discussions (CPD). 1. Submission; 2. Access review; 3. Technical corrections; 4. Publication as Discussion paper; 5. Comments; 6. Final response; 7.Post-discussion editor decision; 8. Revisions; 9. Peer-review completion; 10. Final revised publication.

Two-stage public peer review as practised in the scientific journal Climate of the Past (CP) and its discussion forum Climate of the Past Discussions (CPD). 1. Submission; 2. Access review; 3. Technical corrections; 4. Publication as Discussion paper; 5. Comments; 6. Final response; 7.Post-discussion editor decision; 8. Revisions; 9. Peer-review completion; 10. Final revised publication.

In the first stage, the manuscript undergoes a rapid pre-screening and is immediately published as a ‘discussion paper’, in the journal discussion forum. During the next eight weeks or so, the paper is reviewed by the referees, as well as the scientific community. Referees and other scientists can leave comments which are published alongside the paper. The referee’s comments can be anonymous, or signed, whilst the public comments are always signed. Authors can actively participate in the discussion by clarifying remarks and offering further details to those reading the discussion paper.

The second stage of review follows: if the editor is satisfied with the author’s responses to the comments, the manuscript can be accepted for publication. If the editor still has some concerns about the publication, further revisions will be carried out until a final decision is reached. If necessary, the editor may also consult referees in the same way as during the completion of a traditional peer-review process. In order to increase transparency, some journals also publish a report that documents all changes to the paper since the end of the public discussion.

The system offers advantages to the authors, referees, editors and even the reader. The publication of the ‘discussion paper’ means that research is rapidly disseminated. Added to which, the interactive peer review and discussion means that authors receive feedback directly and can participate in the discussion. The final published research undergoes a full peer-review process, in addition to comments from other scientists, assuring the quality of the research, that is published in EGU journals.

On average, it takes approximately 200 days for a manuscript to complete its journey from submission to publication. However, this time can vary from journal to journal and manuscript to manuscript. This video, produced by our publisher Copernicus, shows the review times for various EGU Journals. Not only that, the average length of time the manuscript spends at each of the stages from submission to publication is broken down, too.

Maybe next time you come to publish your research findings you’ll consider submitting your manuscript to one of the EGU journals. You can learn more about the EGU publications by following this link. To submit your manuscript, head over to the website of any of the EGU journals, and look for the author guidelines and resources for reviewers.

Some food for thought to finish off this post: Have you ever considered the global journey a manuscript goes on after it is submitted? Using an article from Atmospheric Chemistry and Physics, Copernicus produced a video tracking its globetrotting journey: from its birth in Norway and collaborations in eight different countries, to its editor in Switzerland and referees spanning Europe and Asia, the global impact of this manuscript is truly remarkable.

Did you know you can follow many of the EGU journals on Twitter, too? With links to useful journal information, highlight and discussion papers, the social media platform provides a quick way to keep up to speed with the journals. Please follow this link to find out which journals are on Twitter.

Do you have any questions about EGU journals that were not answered in this post? Get in touch through the comments below.

References

Pöschl, U.: Multi-stage open peer review: scientific evaluation integrating the strengths of traditional peer review with the virtues of transparency and self-regulation, Frontiers in Computational Neuroscience, 6, 33, 1-16, doi:10.3389/fncom.2012.00033, 2012.