This category contains 13 posts

Coring on a larger scale

Hammering in the core barrel with a road drill

Hammering in the core barrel with a road drill

The older the sediments, the more macho the equipment. Do you want to core a thousand years of salt marsh sediments? Just bring your hand auger and a gouge. And some muscle power, and a willingness to get really close to the muddy side of science. Do you want to core through interglacial sediments? That might not be so easy. As the name “interglacial” already suggests; these sediments are quite likely to be wedged between glacial sediments. And these may very well consist of gravelly stuff that’s awful to core through. If you need to drill through these to get to the sediments of your choice, bring at least a road drill. The percussive force of the drill will break through all the pesky flints you might encounter below. And a core barrel that’s rammed down with such force won’t be easily pulled out, so a big sturdy jack system is needed to pull the barrel up through the sucking mud and obstructing gravel.

Jacking out the core barrel

Jacking out the core barrel

A set-up like that can take you through many metres of unforgiving sediment, but there are limits to it. We know that because we tried it. If the core barrel is stuck, you have to pull the levers of the jack with all the power you can muster, but you might find what that results in is that you push the jack into the ground, rather than pull the barrel up. You might add some solid wooden beams to place under the jack to stop it from sinking into the ground; that will just break them. We tried that too! So there is a moment when you have to upgrade from the road drill. And the next step up is quite a step. The next step up is a drill rig. We had pushed the limits of the road drill set-up in the hunt for our iGlass interglacial sediments. So we had to take the next step. Fortunately, we had expected that, and there was budget for it.

The drill rig erected at Horse Fen

The drill rig erected at Horse Fen

The difference between a road drill and a drill rig is mainly the size. Another difference is that if you rent it, you get people to work it with that. So from struggling through brambles and barbed wire to get to a muddy field where we had to do everything physically possible to not lose the core barrel underground, we were suddenly upgraded to overseers who watch other people get muddy and achy and tired. And these muddy, achy and tired people would give us what we couldn’t possibly get ourselves: wide, intact sediment cores, all the way through the interglacial sediments to whatever lies below. And they delivered!

It was in rural Norfolk we got to meet our drillers. They arrived in a Land Rover with the rig as a trailer behind it. We asked them to set it up at Horse Fen, one of our critical field sites, where we had not been able to core the lower contact of the interglacial sediments. We had to set up at some distance from the old drill holes, in order no not disturb our badger neighbours. So the men erected the quadripod, hammered metres of casing into the ground, and started drilling through the glacial sands on top of our interglacial clays. These we don’t need for our research, so we just chucked these away. That saves time. They drilled down to where we expected the clay to start. And they drilled deeper. And deeper. We started to get worried. By the time we were wondering if they were drilling into an entirely glacial succession we hit the clay. The stratigraphy is very laterally variable in this area! We cored and retrieved the clay, which was a lot thicker than we expected, and finally hit the freshwater peats. And then the rig did what we had hired it for: it drilled through these. We knew we had a beautiful, undisturbed contact in our core liner. What would we find below? That was something we would not know until we got to the lab!

Extracting the core from its liner

Extracting the core from its liner

Sealing the core sections with warm wax

Sealing the core sections with warm wax

Coring in the dark

Coring in the dark

Removing a section of casing

Removing a section of casing

Probable unstable Pine Island Glacier retreat and sea level rise (new study)

Prof. Tony Payne (Bristol University) contributing author on recent study (Favier et al., 2014. Nature Climate Change doi:10.1038/nclimate2094) showing that Pine Island Glacier’s grounding line is probably engaged in an unstable 40 km retreat. Using ‘state-of-the-art’ ice-sheet modelling, the team demonstrated that the dynamic contribution to sea level rise will remain at a significantly higher level compared with conditions prior to the retreat (equivalent to 3.5–10 mm eustatic sea-level rise over the 20 years).

iGlass EGU session


CL5.11: Sea level in interglacials as a constraint on future changes

iGlass will be running a session at EGU2014. We would like to strongly encourage you to submit an abstract to our session (deadline for abstract submission: 16th January 2014)

Session details: Sea level appears to have been at a higher level than today in at least some of the recent interglacial periods. In this session, we aim to understand how the respective climate histories led to those higher sea levels, and assess how this information can help us constrain projections for future sea level over a range of timescales. Contributions will be welcome that:

  • derive sea level in any of the Quaternary interglacials, either at a single site or across the globe
  • describe or model the (polar) climates that led to higher sea levels
  • model interglacial ice sheet histories, or the respective sea levels
  • link past sea levels with future projections

The session will include work from the UK project iGLASS, but other contributions addressing the above questions will be equally welcome.

Convenors: Eric Wolff, Fiona Hibbert and Dan Lunt

iGlass paper: A geological perspective on potential future sea-level rise

Sea-level versus carbon dioxide concentrations

A new paper by iGlass members suggest modern sea level changes is rapid by past interglacial standards (Rohling et al., 2013 Scientific Reports).

“During ice-age cycles, continental ice volume kept pace with slow, multi-millennial scale, changes in climate forcing. Today, rapid greenhouse gas (GHG) increases have outpaced ice-volume responses, likely committing us to > 9 m of long-term sea-level rise (SLR). We portray a context of naturally precedented SLR from geological evidence, for comparison with historical observations and future projections. This context supports SLR of up to 0.9 (1.8) m by 2100 and 2.7 (5.0) m by 2200, relative to 2000, at 68% (95%) probability.”

The research led by Prof. Eelco Rohling and Dr Ivan Haigh suggests that comparison of present changes in sea level to the natural context outlined in this paper, may be used to identify if and when sea-level response becomes ‘special’ (i.e., unprecedented during geological interglacials).

Professor Rohling concludes: “For the first time, we can see that the modern sea-level rise is quite fast by natural standards. Based on our natural background pattern, only about half the observed sea-level rise would be expected. Although fast, the observed rise still is (just) within the ‘natural range’. While we are within this range, our current understanding of ice-mass loss is adequate. Continued monitoring of future sea-level rise will show if and when it goes outside the natural range. If that happens, then this means that our current understanding falls short, potentially with severe consequences.”

Australia’s 9 News interview with Prof. Eelco Rohling:

UK Wave 102 radio interview with Dr Ivan Haigh:


IPCC sea level rise projection probably too low, says expert survey

In its most recent report, the Intergovernmental Panel on Climate Change’s  predicted sea levels are likely to rise by between 0.26 m and 0.97 m by 2100 – a range encompassing both its highest and lowest emissions scenarios. But according to a new survey of sea level experts, the results of which have been published recently on line in Quaternary Science Reviews, that range might be an underestimate. In the study 90 researchers from 18 different countries were asked for their expert opinion on future sea level rise.Two thirds of those questioned said they thought sea levels could rise higher than the IPCC’s upper estimate for the end of the century.

Read  Article …

Link to paper …

Introducing the Liverpool team

Over the coming weeks we will introduce members of each team working on the iGlass consortium project. Today we will introduce the team from the National Oceanography Centre in Liverpool.

Dr Mark Tamisiea

Mark Tamisea

Mark Tamisiea is a geophysicist that studies the motion of the Earth’s crust and variations of water depth in the oceans caused by past and present changes of the ice sheets. This collective response of the crust ond oceans is typically called glacial isostatic adjustment (GIA). His Ph.D. in physics from the University of Colorado at Boulder examined how solid-solid phase transitions in the Earth’s mantle might affect observations of GIA. Starting with his post-doc at the University of Toronto, his work has focused on the regional sea level changes caused by GIA. Understanding the regional differences is vital to interpreting the causes of past and present sea level change. Mark has been at the National Oceanography Centre (formally the Proudman Oceanographic Laboratory) since 2007 and prior to that was at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts.

Dr Svetlana Jevrejeva

Svetlana JevrejevaSvetlana Jevrejeva is a physical oceanographer who works for NOC Liverpool since 2002. Her main research interests are in the variability of global and regional sea level change and development and application of advanced statistical methods. She had contributed to the development of the wavelet coherence method and is author of the unique sea level reconstruction since 1700. She has major publications in the field of time series analysis and the application of novel statistical methods to earth science problems. During the Fifth Assessment report of Intergovernmental Panel of Climate Change (IPCC) she was a Lead Author of the Working Group 1 chapter on Sea level changes. Recent work has focused on sea level projections by 2100, changes in extreme sea levels in the past and their link to climate change.

Dr André Düsterhus

André DüsterhusAndré Düsterhus is a meteorologist specialised in statistical data analysis. He is part of iGlass since 2013 and is working on the connection between GIA modelling and observations of the sea-level variations in the past interglacials. This is done by using verification and data assimilation techniques with a focus on Bayesian statistics. Prior to his appointment at NOC Liverpool, André had received his diploma and PhD in meteorology at the University of Bonn and worked within the climate dynamics workgroup of Andreas Hense. His PhD thesis covered the development of quality assurance procedures within data publication processes. A focus was set therein on the development of statistical quality assurance tests on general data and data peer review schemes.

Big, unicellular science


A shallow water foraminifer, Ammonia sp. (it’s about 0.4 mm big)

Metres of sea-level change. Hundreds of thousands of years. The entire globe. The scale of the iGlass research project is rather large. But some of the research is based on the humblest of creatures: benthic foraminifera.
If you have a really big one it might be an entire millimetre. Benthic foraminifera are unicellular protists who live on top of, or in the top layer of, marine sediment. Every species has its own niche; for instance, some like coarse sediments, some like fresh food, some like warm water, etcetera. Some of the more adventurous species even live in salt marshes. These are, if you will, the scuba divers among foraminifera; all foraminifera need salt water to live, but these brave souls have become accustomed to do without for substantial amounts of time.

Three specimens of Aubignyna perlucida; two of these have their shells filled with pyrite nodules

The reason why foraminifera, in spite of being such modest creatures, get so much attention from the palaeoclimate community is that they build some sort of skeleton, and aretherefore often very well preserved in sediments. They can be tens of millions of years old and still look like they died last week. They take the information they contain into their graves, and in this case that’s a good thing. If you know which species prefers what environment, you can “read” sediments they are found in.

Drilling a core in sediments that are several hundreds of thousands of years old

The York and Durham teams drilled cores through interglacial sediments.

We drilled in the middle of Norfolk, but we know that area has been inundated in previous interglacials, and indeed, we found both freshwater and marine sediments in our cores. And using the foraminifera in them, we are reading them. We are looking for changes reflected in the various species encountered; will we get a gradual change from the shallowest foraminifera, which are the ones that actually live above sea level but still within reach of high tide, through the ones that live in shallow water, to those that prefer deeper waters? Or will we see several of such sequences? Or an instantaneous shift from no foraminifera to relatively deep-water species? Watch this space for results…

The foraminifera sorted by species
(each numbered rectangle is about 2.3 mm wide)

We found some 10, 000 foraminifera (and counting). They were picked out of the samples by two different scholars, so we keep them all in order to be able to check we have comparable ideas of which species is which (since you ask; no, identifying the species is not a straightforward task). Keeping them also allows us to always go back to the source material in case of questions arising. And after the questions iGlass asks have been answered, who knows what other questions such a collection can help tackle!

Introducing the Bristol team

Over the coming weeks we will introduce members of each team working on the iGlass consortium project. Today we will introduce the team from the School of Geographical Sciences at the University of Bristol.

Professor Tony Payne

Tony payneTony is a Professor of Glaciology in the School of Geographical Sciences and has a BSc in Environmental Science from the University of Stirling and a PhD in Geography from the University of Edinburgh. His PhD focussed on the numerical modelling of former ice sheets. Tony’s work today mainly centres on the development and application of numerical models of glacier and ice sheet flow in order to understand the evolution and dynamics of ice streams, and their effect on the stability of ice sheets. He has a particular interest in modelling the evolution of  Pine Island Glacier in West Antarctica.

Tony is a co-director of the Centre for Polar Observation and Modelling (CPOM) and was heavily involved in the recent European project ICE2SEA. Tony is also a lead author of the chapter on sea level change in the very recently published 5th IPCC report.

Dr Dan Lunt

Dan LuntDan Lunt is a Reader in Climate Science in the School of Geographical Sciences and has an MPhys from the University of Oxford and a PhD on modelling the dust cycle during the Last Glacial Maximum from the University of Reading. His research interests are broad but with a particular focus on climate – ice sheet interactions during the past and in the future. Dan aims to understand the mechanisms affecting past climate change using a model-data synthesis approach . This allows models to test hypotheses derived from interpretation of paleo-data while also providing the data community with information where useful data can be collected to test new hypotheses derived from models.

Dan is an  executive editor of the EGU journal, Geoscientific Model Development, which is primarily for model descriptions, from box models to GCMs. The philosophy behind the journal, is to improve rigour and traceability in climate modelling.  He is also involved in the iGlass related European Project Past4Future and is a contributing author of the chapter on past climate change in the 5th IPCC report.

Dr Joy Singarayer

joyJoy Singarayer is an Associate Professor of Palaeoclimatology in the Department of Meteorology at the University of Reading, having recently left the School of Geographical Sciences at the University of Bristol.  Her interests  are in Quaternary climate change and further back in time with an emphasis on understanding interactions between humans, land cover/use, and climate, prehistoric and present.

Apart from iGlass, Joy has been and is involved on the following projects: terrestrial methane cycling during Paleogene greenhouse climates (NERC), the Palaeoclimate Model Intercomparison Project (PMIP3) – LGM and Holocene terrestrial carbon fluxes and climate, climate change in the last glacial cycle (BBC) and cooling the climate with crops using biogeoengineering (DEFRA).

Dr Emma Stone

Emma StoneEmma Stone is a Research Associate in the School of Geographical Sciences. She has been at Bristol since 2006 where she completed a PhD (supervised by Dan Lunt and Paul Valdes) on the impact of vegetation feedbacks on the evolution of the Greenland ice sheet under future and past climates.  Previously Emma undertook an MEarthSci at the University of Bristol and an MSc in Applied Meteorology at the University of Reading.  She is particularly interested in understanding climate – ice sheet interactions during past warm periods.

As a researcher for the European Past4Future and iGlass projects, Emma uses climate models of various complexity to model the climate interactions during the Last Interglacial (LIG) period with an emphasis on model-data comparison and is currently working on developing a robust statistical methodology for model-data comparison.  The climate output will be used in conjunction with ice sheet modelling to predict sea-level change during the LIG.

Mr Matthew Whipple

Matt WhippleMatt Whipple is a PhD student in the  Geographical and Earth Science Departments and is supervised by Mark Siddall, Eric Wolff, Joy Singarayer and Dan Lunt. Before starting his PhD in 2011 Matt completed a BSc in Geophysics at the University of Liverpool. His PhD is funded by the iGlass project and is focussed on  investigating changes in the Antarctic ice sheet and contributions to sea level during the LIG, and other past warm periods.  He  uses several methodologies which involve combining output from glacio-isostatic adjustment models, climate models, and ice core isotope records.

Introducing the Cambridge team

Over the coming weeks we will introduce members of each team working on the iGlass consortium project. Today we will introduce the team from the British Antarctic Survey and the University of Cambridge.

Professor Eric Wolff

ImageEric Wolff is a Royal Society Research Professor in the Department of Earth Sciences at Cambridge University. After graduating as a chemist, he has studied ice cores from the Antarctic and Greenland for the past 30 years, using them to understand changing climate, as well as changing levels of pollution in remote areas. He also carries out research into the chemistry of the lower parts of the Antarctic atmosphere.

Until June 2013, he had worked at the British Antarctic Survey, leading their programme: “Chemistry and Past Climate”.  He chaired the science committee of the European Project for Ice Coring in Antarctica (EPICA), which produced 800,000 year records of climate from the Dome C (Antarctica) ice core and co-chairs the international initiative (IPICS) to coordinate future ice core research.  He has a strong interest in understanding the similarities, differences and consequences of the interglacials of the last 800,000 years.

Dr Rob Mulvaney

ImageRobert Mulvaney is the Science Leader of the Chemistry and Past Climate programme at the British Antarctic Survey.  He is an analytical chemist and palaeoclimatologist researching climate and environment of the past using chemistry and water isotope data from the analysis of ice cores.  Particularly interests include: the transition from the Last Glacial Maximum to the Holocene; millennial-scale climate change; location of chemical species in ice and diagenesis during burial; permanent gas isotopes trapped in ice as indicators of ice sheet response to climate; trace gases in ice and firn as evidence of anthropogenic changes to the atmosphere.

He is responsible for the UK ice core drilling operations in Antarctica with 18 field seasons experience.  He has worked further five seasons in the Arctic with multinational ice drilling projects, including the recent NEEM Deep Ice Core Drilling Project in Greenland.  Major successes include leading the ice core drilling projects to bedrock on Berkner Island (948m), James Ross Island (364m) and Fletcher Promontory (654m) in Antarctica. In Cambridge he leads a small team working in a modern analytical laboratory alongside a -25°C cold-room measuring the chemistry of ice cores.

Dr Katy Pol

ImageKaty Pol is a palaeoclimatologist at the British Antarctic Survey (BAS). Graduated in Mathematics and Physics, she completed her PhD at the Laboratoire des Sciences et du Climat et de l’Environnement (LSCE) in France in 2011, exploring the millennial to sub-millennial scale climate variability occurring during interglacial periods as recorded in the EPICA Dome C ice core. As part of her post-doc position at BAS, she is involved in the European Past4Future and UK iGLASS projects, combining her knowledge in interglacial climates and ice cores to investigate climatic changes (in sea ice extent, air temperatures or sea surface temperatures for instance) affecting polar regions during warm climatic periods.

Within the iGLASS project, she is in particular in charge of compiling data from different types of archives (e.g. marine sediments, terrestrial sediments or ice cores) to provide a clear view of what were the climatic states of polar regions during the past MIS 7, 9 and 11 interglacial periods. This aims to assess the response of polar ice-sheets to different climatic conditions, a key point when wanting to better understand the processes involved in sea level rise.

Dr Emilie Capron

Emilie Capron is a palaeoclimatologist. She joined the British Antarctic Survey in 2010 after completing a Ph.D at the Laboratoire des Sciences du Climat et de l’Environnement (France) where she analysed the air trapped in Antarctic and Greenland ice cores (air isotopic composition and methane concentration) in order to characterise the millennial-scale climatic variations during the last glacial inception and the early glacial period.

As part of the iGlass and the European Past4Future projects, she is working on a high latitude compilation of data on air and sea surface temperature changes (derived from marine sediment and ice cores) over the Last Interglacial period (115 000-130 000 years ago). This work deals in particular with the development of a common temporal framework between marine sediment and ice core records in order to provide a robust reconstruction of the sequence of climatic events over this time interval. This work will be used both as inputs for ice sheet modelling and targets for climate modelling of the Last Interglacial. In parallel to the iGlass project, Emilie analyses the ice (cation and anion content) and the trapped air (air isotopic composition) in Antarctic ice cores in order to provide constraints on the past evolution of Antarctic firns during large climatic transitions such as a deglaciation. She uses this information to help improving ice core chronologies.

IPCC 5th Assessment WG1 summary

A summary for policy makers was released today. Itcover includes is a clear statement that humans have influenced climate system.

“As the ocean warms, and glaciers and ice sheets reduce, global mean sea level will continue to rise, but at a faster rate than we have experienced over the past 40 years,” said Co-Chair Qin Dahe.

From the summary of thesea level chapter: “There is very high confidence that maximum global mean sea level during the last interglacial period  129,000 to 116,000 years ago) was, for several thousand years, at least 5 m higher than present and high confidence that it did not exceed 10 m above present. During the last interglacial period, the Greenland ice sheet very likely contributed between 1.4 and 4.3 m to the higher global mean sea level, implying with medium confidence an additional contribution from the Antarctic ice sheet. This change in sea level occurred in the context of different orbital forcing and with high-latitude surface temperature, averaged over several thousand years, at least 2°C warmer than present (high confidence).” (Approved summary for policy makers WGI AR5-SPM_Approved27Sep2013)

Further information: link to the IPCC

November 2020

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