Unlocking the secrets of the seafloor: The future of scientific ocean drilling

Close to 600 scientists from 21 countries met Sept. 23 – 25 2009 in Bremen, Germany, to outline major scientific targets for a new and ambitious ocean drilling research program. The scientific community envisions that this program will succeed the current Integrated Ocean Drilling Program (IODP), which ends in 2013. The outcome of the Bremen meeting will result in a new science plan, enabling scientific ocean drilling to take on a central role in environmental understanding and stewardship of our planet in the 21st century.

“This is a truly historic meeting”, said the IODP vice-president Hans Christian Larsen. “Never before have so many scientists from the ocean drilling community met in one place. We were especially pleased to see so many young scientists – these researchers represent the next generation who will lead the new ocean drilling programme, which is expected to start in 2013.”

The 600 scientists attending the meeting discussed both established and new research fields, such as the co-evolution of life and the planet, processes in the Earth’s core and mantle, climate change, and new approaches to capture and store the greenhouse gas carbon dioxide (CO2) in the Earth’s crust. Potential predictability of geohazards such as volcanic eruptions, earthquakes and tsunamis were also addressed, in part linked to development of sub-seafloor laboratories as much as 6 km deep into the seabed.

Ocean drilling has already revealed many exciting discoveries such as confirmation of microbial life up to 1,600 metres below the seafloor in rocks as old as 111 million years. Scientists have now started to explore this ‘deep biosphere’, which may have a biomass equal to that of the tropical rain forest. But many critical questions remain unanswered: How did these ecosystems develop? Can they tell us about the potential for life on other planets? Can marine microbial communities play a role in the development of new biotechnologies and pharmaceuticals?

During his plenary talk, Alan Mix of Oregon State University pointed out that the current level of CO2 injection into Earth’s atmosphere soon will bring the CO2 concentration to a level not seen for many million of years and on par with that of severe greenhouse conditions of the geological past. Only ocean drilling can provide records of the environment that ruled during these warm episodes during Earth’s history, and investigate the true sensitivity of the climate to changes in CO2 concentration.

Ocean research drilling started more than four decades ago as one of the most ambitious projects in the history of marine science. Since then, about 200 expeditions have been completed and more than 350 kilometres of core have been recovered, documenting a much more dynamic Earth and climate than was previously thought to exist. In recent years, IODP, using multiple drilling platforms, has drilled in extremely challenging environments, such as shallow water carbonate reef systems very sensitive to sea-level change and in the high Arctic, the last frontier area of ocean exploration on the Earth. Today, even deep drilling, up to ten kilometres beneath the drillship is possible.

These investigations have revolutionised the understanding of how the Earth works. A future ocean drilling programme will play a pivotal role in enhancing this knowledge by using new technologies and installation of permanent laboratories deep below the ocean floor. As Alan Mix told the conference participants “The beginning is now!”

Recovery Act funds will upgrade earthquake monitoring

Grants totaling $5 million under the American Recovery and Reinvestment Act are being awarded to 13 universities nationwide to upgrade critical earthquake monitoring networks and increase public safety.

“These stimulus grants will save lives as well as create jobs,” Secretary of the Interior Ken Salazar said today. “More than 75 million Americans in 39 states face the risk of earthquakes. Through the modernization of seismic networks and data processing centers, scientists will be able to provide emergency responders with more reliable, robust information to save lives and reduce economic losses.”

Grants are awarded by the U.S. Geological Survey, and monitoring is a key component of the USGS Advanced National Seismic System. ANSS is a national network of sophisticating shaking monitors placed both on the ground and in buildings in urban areas. The ANSS “strong motion” instruments give emergency response personnel real-time maps of severe ground shaking and provide engineers with information to create stronger and sounder structures for homes, bridges, buildings, and utility and communication networks.

“These investments under the American Recovery and Reinvestment Act will provide jobs for the manufacturers of the equipment, the geophysical contractors who perform installations, and the colleges and universities that run regional earthquake networks and are training the next generation of earthquake scientists in partnership with USGS,” Salazar noted.

In California and other high-hazard regions, some parts of the current system include 40-year-old technology, and even the systems most recently upgraded date back to 1997. Think about what a 12-year-old computer looks like. Stimulus funding will replace old instruments with state-of-the-art, robust systems across the highest earthquake hazard areas in California, the Pacific Northwest, Alaska, the Intermountain West, and the central and eastern United States.

The new monitoring systems will be more energy-efficient than the ones they replace and will make solar power the primary power source in remote locations. Engaging students in the siting and installation will provide a unique educational experience and help to train the next generation of earthquake scientists.

Because the investments will modernize aging equipment at existing stations, they do not represent out-year commitments and the new equipment should lower future maintenance costs. The investments in earthquake monitoring meet the stated Recovery Act criteria of being “temporary, targeted and timely” – spending that will flow directly into the economy.

Universities receiving funding include: Montana Tech of the University of Montana; California Institute of Technology; University of Oregon; University of Utah; University of California, San Diego; University of Washington; Saint Louis University; University of Memphis; Boston College, University of Nevada, Reno; University of California, Berkeley; Columbia University; and the University of Alaska, Fairbanks.

Peruvian glacial retreats linked to European events of Little Ice Age

<IMG SRC="/Images/331493556.jpg" WIDTH="350" HEIGHT="234" BORDER="0" ALT="University of New Hampshire master's student Jean Taggart '09, coauthor of a new study published in this week's Science, takes samples from a glacial moraine in southern Peru. – Joe Licciardi”>
University of New Hampshire master’s student Jean Taggart ’09, coauthor of a new study published in this week’s Science, takes samples from a glacial moraine in southern Peru. – Joe Licciardi

A new study that reports precise ages for glacial moraines in southern Peru links climate swings in the tropics to those of Europe and North America during the Little Ice Age approximately 150 to 350 years ago. The study, published this week in the journal Science, “brings us one step closer to understanding global-scale patterns of glacier activity and climate during the Little Ice Age,” says lead author Joe Licciardi, associate professor of Earth sciences at the University of New Hampshire. “The more we know about our recent climate past, the better we can understand our modern and future climate.”

The study, “Holocene glacier fluctuations in the Peruvian Andes indicate northern climate linkages,” was borne of a convergence of a methodological breakthrough in geochronological techniques and Licciardi’s chance encounter with well-preserved glacial moraines in Peru.

On vacation in 2003, Licciardi was hiking near the well-known Inca Trail when he noticed massive, well-preserved glacial moraines – ridges of dirt and rocks left behind when glaciers recede — along the way, about 25 kilometers from the ruins of Machu Picchu. “They very clearly mark the outlines of formerly expanded valley glaciers at various distinct times in the recent past,” he says. But Licciardi, who had no geologic tools with him at the time, did not take any samples.

Two years later, coauthor David Lund, assistant professor of geology at the University of Michigan and a friend of Licciardi’s from graduate school, was in the same region and offered to chisel off some samples of the salt-and-pepper colored granitic rock. “Dave also recognized the potential of this site and shared my enthusiasm for initiating a study,” says Licciardi. “That was the catalyst for turning our ideas into an actual project.” Licciardi returned in 2006 to the slopes of Nevado Salcantay, a 20,000-foot-plus peak that is the highest in the Cordillera Vilcabamba range. Over the next two years, he and his graduate student Jean Taggart, also a coauthor, collected more rock samples from the moraines.

The researchers analyzed the samples using a surface exposure dating technique — measuring the tiny amounts of the chemical isotope beryllium-10 that is formed as cosmic rays bombard exposed surfaces — to place very precise dates on these relatively young glacial fluctuations. Licciardi and Taggart, who received a master’s degree from UNH last month, worked with coauthor Joerg Schaefer, a geochemist at Columbia University’s Lamont-Doherty Earth Observatory, to produce some of the youngest ages ever obtained from the beryllium isotope dating method.

“The ability to measure such young and precise ages with this method provides us with an exciting new way to establish the timing of recent glacier fluctuations in places far afield from where we have historical records,” says Licciardi. Because the Little Ice Age – from about 1300 AD to 1860 AD — coincides with historical accounts and climate observations in Europe and North America, the event is well documented in the Northern Hemisphere. In remote and sparsely inhabited areas like the Peruvian Andes, however, chronologies of Little Ice Age glacial events are very scarce.

A key finding of the study is that while glaciers in southern Peru moved at similar times as glaciers in Europe, the Peruvian record differs from the timing of glacier fluctuations in New Zealand’s Southern Alps during the last millennium, as reported in another recent study in Science led by Schaefer.

“This finding helps identify interhemispheric linkages between glacial signals around the world. It increases our understanding of what climate was like during the Little Ice Age, which will in turn help us understand climate drivers,” says Taggart.

“If the current dramatic warming projections are correct, we have to face the possibility that the glaciers may soon disappear,” adds Schaefer.

Licciardi and his colleagues will continue working in Peru toward a more complete understanding of glacial expansion during the Little Ice Age – and their subsequent retreat. “Our new results point to likely climate processes that can explain why these glaciers expanded and retreated when they did, but there are still many open questions,” he says. “For example, what’s the relative importance of temperature change versus precipitation change on the health of these glaciers?” The research team plans to explore this question using coupled climate-glacier models that evaluate the sensitivity of glaciers in southern Peru to the two main factors that drive glacier expansion – cold temperatures and abundant snowfall.

‘Rosetta Stone’ of supervolcanoes discovered in Italian Alps

Some lower peaks in the Alps. These are in the Chamonix Valley, near the Mer de Glace.
Some lower peaks in the Alps. These are in the Chamonix Valley, near the Mer de Glace.

Scientists have found the “Rosetta Stone” of supervolcanoes, those giant pockmarks in the Earth’s surface produced by rare and massive explosive eruptions that rank among nature’s most violent events. The eruptions produce devastation on a regional scale – and possibly trigger climatic and environmental effects at a global scale.

A fossil supervolcano has been discovered in the Italian Alps’ Sesia Valley by a team led by James E. Quick, a geology professor at Southern Methodist University. The discovery will advance scientific understanding of active supervolcanoes, like Yellowstone, which is the second-largest supervolcano in the world and which last erupted 630,000 years ago.

A rare uplift of the Earth’s crust in the Sesia Valley reveals for the first time the actual “plumbing” of a supervolcano from the surface to the source of the magma deep within the Earth, according to a new research article reporting the discovery. The uplift reveals to an unprecedented depth of 25 kilometers the tracks and trails of the magma as it moved through the Earth’s crust.

Supervolcanoes, historically called calderas, are enormous craters tens of kilometers in diameter. Their eruptions are sparked by the explosive release of gas from molten rock or “magma” as it pushes its way to the Earth’s surface.

Calderas erupt hundreds to thousands of cubic kilometers of volcanic ash. Explosive events occur every few hundred thousand years. Supervolcanoes have spread lava and ash vast distances and scientists believe they may have set off catastrophic global cooling events at different periods in the Earth’s past.

Sesia Valley’s caldera erupted during the “Permian” geologic time period, say the discovery scientists. It is more than 13 kilometers in diameter.

“What’s new is to see the magmatic plumbing system all the way through the Earth’s crust,” says Quick, who previously served as program coordinator for the Volcano Hazards Program of the U.S. Geological Survey. “Now we want to start to use this discovery. We want to understand the fundamental processes that influence eruptions: Where are magmas stored prior to these giant eruptions? From what depth do the eruptions emanate?”

Sesia Valley’s unprecedented exposure of magmatic plumbing provides a model for interpreting geophysical profiles and magmatic processes beneath active calderas. The exposure also serves as direct confirmation of the cause-and-effect link between molten rock moving through the Earth’s crust and explosive volcanism.

“It might lead to a better interpretation of monitoring data and improved prediction of eruptions,” says Quick, lead author of the research article reporting the discovery, “Magmatic plumbing of a large Permian caldera exposed to a depth of 25 km.,” in Geology.

Calderas, which typically exhibit high levels of seismic and hydrothermal activity, often swell, suggesting movement of fluids beneath the surface.

“We want to better understand the tell-tale signs that a caldera is advancing to eruption so that we can improve warnings and avoid false alerts,” Quick says.

To date, scientists have been able to study exposed caldera “plumbing” from the surface of the Earth to a depth of only 5 kilometers. Because of that, scientific understanding has been limited to geophysical data and analysis of erupted volcanic rocks. Quick likens the relevance of Sesia Valley to seeing bones and muscle inside the human body for the first time after previously envisioning human anatomy on the basis of a sonogram only.

“We think of the Sesia Valley find as the ‘Rosetta Stone’ for supervolcanoes because the depth to which rocks are exposed will help us to link the geologic and geophysical data,” Quick says. “This is a very rare spot. The base of the Earth’s crust is turned up on edge. It was created when Africa and Europe began colliding about 30 million years ago and the crust of Italy was turned on end.”

Bristish researchers introduced the term “supervolcano” in the last 10 years. Scientists have documented fewer than two dozen caldera eruptions in the last 1 million years.

Besides Yellowstone, other monumental explosions have included Lake Toba on Indonesia’s Sumatra island 74,000 years ago, which is believed to be the largest volcanic eruption on Earth in the past 25 million years.

Described as a massive climate-changing event, the Lake Toba eruption is thought to have killed an estimated 60% of humans alive at the time.

Another caldera, and one that remains active, Long Valley in California erupted about 760,000 years ago and spread volcanic ash for 600 cubic kilometers. The ash blanketed the southwestern United States, extending from California to as far west as Nebraska.

“There will be another supervolcano explosion,” Quick says. “We don’t know where. Sesia Valley could help us to predict the next event.”

End of an era: New ruling decides the boundaries of Earth’s history

After decades of debate and four years of investigation an international body of earth scientists has formally agreed to move the boundary dates for the prehistoric Quaternary age by 800,000 years, reports the Journal of Quaternary Science.

The decision has been made by the International Commission on Stratigraphy (ICS), the authority for geological science which has acted to end decades of controversy by formally declaring when the Quaternary Period, which covers both the ice age and moment early man first started to use tools, began.

In the 18th Century the earth’s history was split into four epochs, Primary, Secondary, Tertiary, and Quaternary. Although the first two have been renamed Palaeozoic and Mesozoic respectively, the second two have remained in use by scientists for more than 150 years. There has been a protracted debate over the position and status of Quaternary in the geological time scale and the intervals of time it represents.

“It has long been agreed that the boundary of the Quaternary Period should be placed at the first sign of global climate cooling,” said Professor Philip Gibbard. “What we have achieved is the definition of the boundary of the Quaternary to an internationally recognized and fixed point that represents a natural event, the beginning of the ice ages on a global scale.”

Controversy over when exactly the Quaternary Period began has raged for decades, with attempts in 1948 and 1983 to define the era. In 1983 the boundary was fixed at 1.8 million years, a decision which sparked argument within the earth science community as this point was not a ‘natural boundary’ and had no particular geological significance.

Up to now it has been widely felt within the scientific community that the boundary should be located earlier, at a time of greater change in the earth-climate system.

“For practical reasons such boundaries should ideally be made as easy as possible to identify all around the world. The new boundary of 2.6 million years is just that,” concluded Gibbard, “hence we are delighted at finally achieving our goal of removing the boundary to this earlier point.”

“The decision is a very important one for the scientific community working in the field,” said Journal Editor Professor Chris Caseldine. “It provides us with a point in geological time when we effectively did move into a climatic era recognisably similar to the geological present.”

Study shows disparity of effect of climate change on UV radiation

Physicists at the University of Toronto have discovered that changes in the Earth’s ozone layer due to climate change will reduce the amount of ultraviolet (UV) radiation in northern high latitude regions such as Siberia, Scandinavia and northern Canada. Other regions of the Earth, such as the tropics and Antarctica, will instead face increasing levels of UV radiation.

“Climate change is an established fact, but scientists are only just beginning to understand its regional manifestations,” says Michaela Hegglin, a postdoctoral fellow in the Department of Physics, and the lead author of the study published in Nature Geoscience on September 6.

Using a sophisticated computer model, Hegglin and U of T physicist Theodore Shepherd determined that 21st-century climate change will alter atmospheric circulation, increasing the flux of ozone from the upper to the lower atmosphere and shifting the distribution of ozone within the upper atmosphere. The result will be a change in the amount of UV radiation reaching the Earth’s surface which varies dramatically between regions: e.g. up to a 20 per cent increase in UV radiation over southern high latitudes during spring and summer, and a nine per cent decrease in UV radiation over northern high latitudes, by the end of the century.

While the effects of increased UV have been widely studied because of the problem of ozone depletion, decreased UV could have adverse effects too, e.g. on vitamin D production for people in regions with limited sunlight such as the northern high latitudes.

“Both human and ecosystem health are affected by air quality and by UV radiation,” says Shepherd. “While there has been much research on the impact of climate change on air quality, our work shows that this research needs to include the effect of changes in stratospheric ozone. And while there has been much research on the impact of ozone depletion on UV radiation and its impacts on human and ecosystem health, the notion that climate change could also affect UV radiation has not previously been considered. This adds to the list of potential impacts of climate change, and is especially important for Canada as northern high latitudes are particularly affected.”

Solar cycle driven by more than sunspots; sun also bombards earth with high-speed streams of wind

When the solar cycle was at a minimum level in 1996, the Sun sprayed Earth with relatively few, weak high-speed streams containing turbulent magnetic fields (left). In contrast, the Sun bombarded Earth with stronger and longer-lasting streams last year (right) even though the solar cycle was again at a minimum level. The streams affected Earth's outer radiation belt, posing a threat to earth-orbiting satellites, and triggered space weather disturbances, lighting up auroras in the sky at higher latitudes. -  (Illustration by Janet Kozyra with images from NASA, courtesy Journal of Geophysical Research - Space Physics.)
When the solar cycle was at a minimum level in 1996, the Sun sprayed Earth with relatively few, weak high-speed streams containing turbulent magnetic fields (left). In contrast, the Sun bombarded Earth with stronger and longer-lasting streams last year (right) even though the solar cycle was again at a minimum level. The streams affected Earth’s outer radiation belt, posing a threat to earth-orbiting satellites, and triggered space weather disturbances, lighting up auroras in the sky at higher latitudes. – (Illustration by Janet Kozyra with images from NASA, courtesy Journal of Geophysical Research – Space Physics.)

Challenging conventional wisdom, new research finds that the number of sunspots provides an incomplete measure of changes in the Sun’s impact on Earth over the course of the 11-year solar cycle. The study, led by scientists at the National Center for Atmospheric Research (NCAR) and the University of Michigan, finds that Earth was bombarded last year with high levels of solar energy at a time when the Sun was in an unusually quiet phase and sunspots had virtually disappeared.

“The Sun continues to surprise us,” says lead author Sarah Gibson of NCAR’s High Altitude Observatory. “The solar wind can hit Earth like a fire hose even when there are virtually no sunspots.”

The study, also written by scientists at NOAA and NASA, is being published today in the Journal of Geophysical Research. It was funded by NASA and by the National Science Foundation, NCAR’s sponsor.

Scientists for centuries have used sunspots, which are areas of concentrated magnetic fields that appear as dark patches on the solar surface, to determine the approximately 11-year solar cycle. At solar maximum, the number of sunspots peaks. During this time, intense solar flares occur daily and geomagnetic storms frequently buffet Earth, knocking out satellites and disrupting communications networks.

Gibson and her colleagues focused instead on another process by which the Sun discharges energy. The team analyzed high-speed streams within the solar wind that carry turbulent magnetic fields out into the solar system.

When those streams blow by Earth, they intensify the energy of the planet’s outer radiation belt. This can create serious hazards for weather, navigation, and communications satellites that travel at high altitudes within the outer radiation belts, while also threatening astronauts in the International Space Station. Auroral storms light up the night sky repeatedly at high latitudes as the streams move past, driving mega-ampere electrical currents about 75 miles above Earth’s surface. All that energy heats and expands the upper atmosphere. This expansion pushes denser air higher, slowing down satellites and causing them to drop to lower altitudes.

Scientists previously thought that the streams largely disappeared as the solar cycle approached minimum. But when the study team compared measurements within the current solar minimum interval, taken in 2008, with measurements of the last solar minimum in 1996, they found that Earth in 2008 was continuing to resonate with the effects of the streams. Although the current solar minimum has fewer sunspots than any minimum in 75 years, the Sun’s effect on Earth’s outer radiation belt, as measured by electron fluxes, was more than three times greater last year than in 1996.

Gibson said that observations this year show that the winds have finally slowed, almost two years after sunspots reached the levels of last cycle’s minimum.

The authors note that more research is needed to understand the impacts of these high-speed streams on the planet. The study raises questions about how the streams might have affected Earth in the past when the Sun went through extended periods of low sunspot activity, such as a period known as the Maunder minimum that lasted from about 1645 to 1715.

“The fact that Earth can continue to ring with solar energy has implications for satellites and sensitive technological systems,” Gibson says. “This will keep scientists busy bringing all the pieces together.”

Buffeting Earth with streams of energy

For the new study, the scientists analyzed information gathered from an array of space- and ground-based instruments during two international scientific projects: the Whole Sun Month in the late summer of 1996 and the Whole Heliosphere Interval in the early spring of 2008. The solar cycle was at a minimal stage during both the study periods, with few sunspots in 1996 and even fewer in 2008.

The team found that strong, long, and recurring high-speed streams of charged particles buffeted Earth in 2008. In contrast, Earth encountered weaker and more sporadic streams in 1996. As a result, the planet was more affected by the Sun in 2008 than in 1996, as measured by such variables as the strength of electron fluxes in the outer radiation belt, the velocity of the solar wind in the vicinity of Earth, and the periodic behavior of auroras (the Northern and Southern Lights) as they responded to repeated high-speed streams.

The prevalence of high-speed streams during this solar minimum appears to be related to the current structure of the Sun. As sunspots became less common over the last few years, large coronal holes lingered in the surface of the Sun near its equator. The high-speed streams that blow out of those holes engulfed Earth during 55 percent of the study period in 2008, compared to 31 percent of the study period in 1996. A single stream of charged particles can last for as long as 7 to 10 days. At their peak, the accumulated impact of the streams during one year can inject as much energy into Earth’s environment as massive eruptions from the Sun’s surface can during a year at the peak of a solar cycle, says co-author Janet Kozyra of the University of Michigan.

The streams strike Earth periodically, spraying out in full force like water from a fire hose as the Sun revolves. When the magnetic fields in the solar winds point in a direction opposite to the magnetic lines in Earth’s magnetosphere, they have their strongest effect. The strength and speed of the magnetic fields in the high-speed streams can also affect Earth’s response.

The authors speculate that the high number of low-latitude coronal holes during this solar minimum may be related to a weakness in the Sun’s overall magnetic field. The Sun in 2008 had smaller polar coronal holes than in 1996, but high-speed streams that escape from the Sun’s poles do not travel in the direction of Earth.

“The Sun-Earth interaction is complex, and we haven’t yet discovered all the consequences for the Earth’s environment of the unusual solar winds this cycle,” Kozyra says. “The intensity of magnetic activity at Earth in this extremely quiet solar minimum surprised us all. The new observations from last year are changing our understanding of how solar quiet intervals affect the Earth and how and why this might change from cycle to cycle.”

Melting of the Greenland ice sheet mapped

This is a map of the ice core drilling locations discussed in the article. -  Center for Ice and Climate, Niels Bohr Institute, University of Copenhagen
This is a map of the ice core drilling locations discussed in the article. – Center for Ice and Climate, Niels Bohr Institute, University of Copenhagen

Will all of the ice on Greenland melt and flow out into the sea, bringing about a colossal rise in ocean levels on Earth, as the global temperature rises? The key concern is how stable the ice cap actually is and new Danish research from the Niels Bohr Institute at the University of Copenhagen can now show the evolution of the ice sheet 11,700 years back in time – all the way back to the start of our current warm period. The results are published in the esteemed journal Nature.

Numerous drillings have been made through both Greenland’s ice sheet and small ice caps near the coast. By analysing every single annual layer in the kilometres long ice cores researchers can get detailed information about the climate of the past. But now the Danish researcher Bo Vinther and colleagues from the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen, in collaboration with researchers from Canada, France and Russia, have found an entirely new way of interpreting the information from the ice core drillings.

“Ice cores from different drillings show different climate histories. This could be because they were drilled at very different places on and near Greenland, but it could also be due to changes in the elevation of the ice sheet, because the elevation itself causes different temperatures” explains Bo Vinther about the theory.

Today the ice sheet is more than three kilometres thick at its highest point and thinning out towards the coast. Four of the drillings analysed are from the central ice sheet, while two of the drillings are from small ice caps outside of the ice sheet itself, at Renland on the east coast and Agassiz which lies just off of the northwest coast of Greenland in Canada.

Small ice caps show the standard

The small ice caps are stable and have not changed in elevation, and even though they lie very far apart from each other on either side of the central ice sheet, they show the same climate history. This means that one can use the small ice caps climate history as a standard reference for the others.

Bo Vinther explains, that the four drillings through the ice sheet would have had the same climate history if there had not been changes in elevation throughout the course of time. It is known that for every 100 meter increase in elevation, there is a 0.6 per mille decrease in the level of the oxygen isotope Oxygen-18, which indicates the temperature in the air. So if there is a difference of 1.2 per mille, the elevation has changed by 200 meters.

By comparing the Oxygen-18 content in all of the annual layers from the four drillings through the ice sheet with the Oxygen-18 content of the same annual layers in the small ice caps, Bo Vinther has calculated the elevation course through 11,700 years.

Temperature sensitive ice sheet

Just after the ice age the elevation of the ice sheet rose slightly. This is because when the climate transitions from ice age to warm age, there is a rapid increase in precipitation. But at the same time, the areas lying near the coast begin to decrease in size, because the ice is melting at the edge. When the ice melts at the edge, it slowly causes the entire ice sheet to ‘collapse’ and become lower.

The calculations show that in the course of about 3,000 years the elevation changed and became up to 600 meters lower in the coastal areas. But in the middle it was a slow process, where the elevation decreased around 150 meters in the course of around 6,000 years. It then stabilised.

The elevations that were found with the help of the Oxygen-18 measurements from the ice cores are checked with other methods, for example, by measuring the air content, which is also dependent upon the elevation.

The new results show the evolution of elevation of the ice sheet throughout 11,700 years and they show that the ice sheet is very sensitive to the temperature. The results can be used to make new calculations for models predicting future consequences of climate changes.

Egg-shaped legacy of Britain’s mobile ice-sheet

The ice sheets that sculpted the landscape of northern Britain moved in unexpected ways and left distinctive egg-shaped features according to new research.

Scientists from Durham University have deciphered the landforms and created a model of the British and Irish Ice Sheet (BIIS) which reveals for the first time how glaciers reversed their flows and retreated back into upland regions from where they originated.

These ice sheet flow patterns created a unique ‘overprinting’ of British glacial landforms 26,000 to 16,000 years ago, leaving distinctive egg-shaped features called ‘drumlins’ across our fields and valleys.

Drumlin-strewn landscapes can be seen along the A66 road through the Eden Valley (near Appleby) and across the Solway and Lake District lowlands, the Northern Pennines, and through the Tyne Gap and the valleys of southern Scotland.

The research, funded by the Natural Environment Research Council, is published in the Journal, Quaternary Science Reviews.

During the last glacial maximum, around 21,500 years ago, the BIIS built up on the high land of the Lake District, north Pennines and Scottish Southern Uplands; as more snow fell in these areas and local ice caps thickened, glaciers flowed into surrounding lowlands as expected.

The new reconstruction of the movement of the ice sheet, compiled by the Durham University research team, reveals an unusual twist once the glaciers filled lowland areas. As the ice sheet evolved from the coalescence of the upland ice caps, it flowed out towards the Irish Sea, eventually becoming so thick over the Solway Lowlands that it reversed its flow back up the valleys, re-adjusting the landforms it had created during earlier stages of growth.

The rolling terrain that walkers can see along many parts of the Pennine Way and that drivers can see along the route of the M6 motorway provide examples of this glacial landscape.

The research team led by Dr David Evans, from the Department of Geography at Durham University plotted the progress of the ice sheet between 26,000 and 16,000 years ago. Using maps of superimposed drumlins, ancient temperature records, and computer modeling, the team profiled the size, extent and flow directions of the ice-sheet, and reconstructed its movement through time.

Dr Evans said: “The stereotypical image of Ice-age Britain is of ice rolling in from the Arctic but this is not an accurate description of what happened. Britain was cold enough for ice to form in the uplands, growing and coalescing to produce an elongate, triangular-shaped dome over NW England and SW Scotland around 19,500 years ago.

“The Ice sheet then moved downhill, as one would expect. Our findings show that the lowland ice became so thick that it began to move in unexpected ways – the ice moved back uphill from where it originally came. Recession and a series of complex ice flow directional switches took place over relatively short timescales.”

Four major ice flows have been identified across northern Britain and Dr Evans’ team has produced case studies of drumlin and lineation mapping that show that these glacier flow directions switched significantly through time.

The pressure of the ice flows became sufficient to deform sediments at the base of the ice sheet, resulting in the moulding of the sediment into streamlined landforms like drumlins.

Many of the fields of northern England and southern Scotland have been cleared of their boulders during hundreds of years of agricultural improvement. This stony, unworkable material was called ’till’, the term now used by glacial researchers to describe sediment laid down at the base of ice sheets and glaciers.

A close look at many of the distinctive stone walls in the region of the North Pennine chain, often reveals the use in their construction of Scottish and Lake District ‘erratics’, stones which are quirks of glacial ice flows. Many of these erratic stones were transported hundreds of miles away from their origin by the complex and often reversed movement of the glaciers.

Dr Evans says: “The Durham model shows that an ice sheet can reverse its flow in a hundred or so years and when this happens, it creates unique features in our landscape. Elongated drumlins and meltwater channels in northern England and southern Scotland provide evidence of this unique phenomenon. ”

“The ice sheet had no real steady state but rather was mobile and comprised constantly migrating dispersal centres and ice divides which triggered significant flow reversals. The occurrence of Lake District material in Pennine dry-stone walls is a clear indication that during the last glaciation of Britain, ice sheet flow directions were at times reversed.”

Five stages of glaciation in Northern Britain:

Build up of snow and ice on higher ground.

Ice thickening results in ice flow down valleys that drain the uplands.

Valley ice from different upland sources fuse or coalesce.

Ice thickens in the lowlands and the ice sheet dispersal centres migrate, forcing ice flows to become independent of the underlying hills and valleys.

In some areas the ice flows reverse and in places (e.g. Vale of Eden) actually move back uphill.

Four flows of glaciation in northern Britain:

Phase I flow was from a dominant Scottish dispersal centre, which transported Criffel granite erratics to the Eden Valley and forced Lake District ice eastwards over the Pennines at Stainmore. Prior to this phase local ice caps over the Lake District and North Pennines forced ice to flow into the lowlands, the reverse of Phase I flow.

Phase II involved easterly flow of Lake District and Scottish ice through the Tyne Gap and Stainmore Gap with an ice divide located over the Solway Firth.

Phase III was a dominant westerly flow from upland dispersal centres into the Solway lowlands and along the Solway Firth due to draw down of ice into the Irish Sea basin;

Phase IV was characterised by unconstrained advance of Scottish ice across the Solway Firth. At this time, and ice sheet had started to uncouple again to produce localized ice retreat back on to the high land of the Lake District and North Pennines (the ice retreated from whence it came). This period saw: a) the development of a vast lake (Glacial Lake Carlisle) over the Solway Lowlands dammed by the Scottish ice advance; b) the cutting of the Melmerby meltwater channels on the Pennine Escarpment by water draining along a glacier margin retreating up the Eden Valley; and c) the deposition of the Brampton kame belt, the largest accumulation of glacial sand and gravel in England.

Digging deeper below Antarctica’s Lake Vida

Antarctica’s Lake Vida, a geologic curiosity that is essentially an ice bottle of brine, is home to some of the oldest and coldest living organisms on Earth. Perpetually covered by more than 60 feet of ice, the brine below — water that is five to seven times more salty than seawater — has been found to be home to cryobiological microbes some 2,800 years old which were revived after a gradual thaw.

That widely reported finding came in 2002 from Peter Doran, associate professor of earth and environmental sciences at the University of Illinois at Chicago. But the discovery raised many new questions. Now, Doran and his department colleague Fabien Kenig with collaborators from the Nevada-based Desert Research Institute will return to Lake Vida late next year for more exploration, funded by a $1.1 million National Science Foundation grant.

Doran and Kenig plan to perform the first-ever drilling entirely through Lake Vida’s thick ice cap, into the brine, and down into sediment below, retrieving about 10 feet or more of core sample for analysis.

“The main goal is to get into that brine pocket and the sediment beneath it to both document and define the ecosystem that’s there today, and the history of that ecosystem,” Doran said.

The sediment samples could yield clues about life in such an extreme environment dating back thousands of years, which could help geoscientists draw a better picture of processes that occur as the Earth moves into colder periods.

“If we took, for example, a Wisconsin lake and started turning the temperatures down during a climatic downturn, what is the impact on the lake’s ecosystem and what strategies are used by living things to survive this extremely cold brine?” Doran said of the salty liquid that hovers around 10 degrees Fahrenheit year-round. “There are few examples on Earth of things shown to live in that water temperature.”

A University of Wisconsin group will drill the ice hole, but special care will be required in preparing the site. A tent will be partitioned to provide both a drilling site cover and adjacent laboratory to analyze samples. It will be sort of like setting up a hospital operating room in the Antarctic cold, with the drill requiring the sanitary cleanliness of a surgeon’s scalpel to prevent any surface contaminants from ruining samples.

Kenig, an organic geochemist, will study the lake’s carbon and organic chemistry as well as molecular fossils in the sediment core. These preserved organic compounds will point to changes in the ecosystem as the lake froze.

“As this environment was isolated for some time, we need to be very cautious not to introduce any external elements that could bias our samples,” Kenig said. To assure sample purity, nothing plastic or rubber will be used in the drilling and all equipment penetrating the lake water and sediment will be sterilized.

While specially preserved samples will be shipped back to UIC and the Desert Research Institute for later analysis, some work, such as microbial counts, will be done on site. Doran’s previous on-site research at Lake Vida found in the ice the highest concentration of nitrous oxide — “laughing gas” — of any ecosystem on Earth. It was a clue that would make any scientist smile.

“This gas is produced by microbes,” Doran said. “That was a hint that we had a viable ecosystem there.”