Energy From Hot Rocks

Two UC Davis geologists are studying the underground chemistry that creates this geyser found on an Icelandic farm. (Robert Zierenberg/UC Davis photo)
Two UC Davis geologists are studying the underground chemistry that creates this geyser found on an Icelandic farm. (Robert Zierenberg/UC Davis photo)

Two UC Davis geologists are taking part in the Iceland Deep Drilling Project, an international effort to learn more about the potential of geothermal energy, or extracting heat from rocks.

Professors Peter Schiffman and Robert Zierenberg are working with Wilfred Elders, professor emeritus at UC Riverside, Dennis Bird at Stanford University and Mark Reed at the University of Oregon to study the chemistry that occurs at high pressures and temperatures two miles below Iceland.

“We hope to understand the process of heat transfer when water reacts with hot volcanic rocks and how that changes the chemistry of fluids circulating at depth,” Zierenberg said. “We know very little about materials under these conditions.”

The university team, funded by the National Science Foundation, will drill up to 4 kilometers, or 2.5 miles, into the rock. It will be one of three boreholes sunk as part of the Iceland Deep Drilling Project, which is supported largely by Icelandic power companies.

The island nation generates more than half of its electrical power from geothermal energy. Hot water and steam from boreholes can be used to run turbines for electricity or directly to heat homes and businesses. Iceland meets the rest of its electricity needs from hydroelectric power, and imports fossil fuels only for transportation.

The U.S. has lots of potential for geothermal energy generation, Zierenberg said. There are several plants in California, including the Geysers region in the north and at Mammoth Lakes. Although its share of energy generation in the state is small, the Geysers is the largest geothermal field in the world, Zierenberg said. There are also numerous abandoned oil and gas boreholes around the country — including in the Central Valley — that could potentially access hot water that could be used for space heating.

That would, however, require something of a cultural change. In Iceland, geothermal heating is used at a community level: hot water is pumped up and circulated around a town or neighborhood. Americans are more accustomed to individual power delivery, Zierenberg said.

The team expects to begin drilling in the summer of 2008.

Antarctic Team To Install Seismographs, Where ‘No Man -Or Woman – Has Gone Before’

Living conditions in Antarctica for researchers are primitive and brutal. Though it will be summer in Antarctica when the Wiens team works there in December and January, temperatures will max out at -30 Fahrenheit. (Credit: Image courtesy of Washington University In St. Louis)
Living conditions in Antarctica for researchers are primitive and brutal. Though it will be summer in Antarctica when the Wiens team works there in December and January, temperatures will max out at -30 Fahrenheit. (Credit: Image courtesy of Washington University In St. Louis)

A team of seismologists from Washington University in St. Louis, like members of the starship Enterprise, will “boldly go where no man has gone before” after Thanksgiving this year.

The team, led by Douglas A. Wiens, Ph.D., Washington University Professor of Earth and Planetary Sciences in Arts & Sciences, will go to remote regions of Antarctica to place seismographs in both east and west Antarctica, to learn about the earth beneath the ice, and glean information about glaciers, mountains and ice streams. The location of their field camp, called AGAP-South, has never been visited by humans before, and the entire region of Antarctica has only been traversed by a Russian team 50 years ago and by a Chinese team last year.

Up until this November, no woman has been in these parts of Antarctica either, but Wiens’ graduate student, Moira Pyle, will hold the distinction of being the first woman to set foot there.

Wiens and the group will install 10 seismographs each in the east and west parts of Antarctica, and an additional 20 instruments next year. Members of the group will spend between one to two months in Antarctica.

What they’ll do on their ‘summer vacation’

It will be summer in Antarctica, with temperatures maxing out at -30 Fahrenheit. The researchers will stay in a heated tent at their base camp, 400 miles from the nearest civilization, South Pole base, and about 3000 miles from New Zealand. They will wear sturdy boots, snow pants and parkas and cover their faces with masks, as the potential for frostbite to exposed skin is very high.

While two of the five will stay at base camp to prepare for the next day, three will be transported as far as 300 miles away to install the seismographs.

The vehicle will be a stout aircraft made in the fifties called a Twin Otter duel prop, sometimes referred to as a Dehaviland-6. There are, of course, no runways on ice, so the aircraft is equipped with skis. They will have a Canadian pilot who will have access to a spreadsheet denoting various caches of fuel throughout the continent. The barrels weighing up to 300 pounds or more are spread throughout the Antarctic.

The effects of the ice and sun will tell the researchers ‘they’re not in Missouri anymore.’

“The surface of the Antarctic looks essentially like a snow-covered western Kansas, but mountains lurk beneath two miles of ice, “said Wiens, who has researched the Antarctic since the 1990s and put in the largest array of seismographs – 43 – ever in the early part of this century. “You see nothing but a vast flat sea of white under constant sunshine. It’s really eerie out there.

“In terms of the east, we have no idea what’s beneath the ice. No one has even taken any rock samples. It’s thought that when the Earth’s climate started to cool millions of years ago, the first glaciers in the world formed in these mountains. But we really don’t know if the mountains were there at the time the glaciers formed.”

Analysis of seismic waves could reveal how old the mountains are and their relationship to the formation of glaciers.

“One of the things we should be able to determine is what’s causing the elevation of the mountains,” he said. “It’s probably either due to a thick crust or hot temperatures in the mantle. If it’s hot temperatures in the mantle, the mantle can’t stay hot for billions of years, so that would tell us that it’s due to fairly recent activity. But if it’s thick crust, we can speculate that it was formed a long time ago.”

Global warming effect?

In west Antarctica, global warming is a concern. Wiens said that simulations show that the ice sheet in west Antarctica could fall apart if the Earth warms up, flooding coastal cities around the world.

Ice streams that are like rivers of ice as much as 80 miles wide are a study focus. Wiens said studies of these features over the past 40 years show some ice streams speeding up, others slowing down. Seismographs can detect sudden motion of the ice streams to help understand what controls their motion. Also, the rate of motion of the ice streams is related to the conditions of the rocks beneath. “We need to know how hot the mantle is. If it’s really hot, the ice will flow easier. If it’s really cold, it won’t flow at all.” said Wiens.

Since this work is part of the International Polar Year, the Washington University group will not be the only researchers working on these projects. There will be Chinese, French, Japanese and Italian seismologists, as well as other Americans, from Ohio State University (OSU), Columbia University, and Pennsylvania State University, among others.

A collaboration with Ohio State University combines the seismic data with global positioning system (GPS) data, in one coordinated project called Polenet. “Their data complement ours in understanding how the loss of ice is related to uplift of the land,” said Wiens. Rounding out the research team are graduate students Michael Barkledge, and David Heeszel, the only one who is a newbie to Antarctica, and Antarctica veteran Patrick Shore, a lecturer and computer specialist in Earth and Planetary Sciences. He has accompanied Wiens on many different seismic expeditions.

One important thing Wiens will stress to the group is sleep. “You have to be careful that you keep sleeping,” he said. “When you first get there, and it’s light all the time, you get jazzed up and want to keep working. Your body doesn’t really tell you to sleep. You get tired, but your eyes are telling you the sun is still out.”

The projects, funded by the National Science Foundation (NSF), are Washington University’s contribution to a celebration of International Polar Year (IPY), 125 years after the first IPY (1882), 75 years after IPY 2 (1932), and 50 years after the first International Geophysical Year. The research period for the celebration is actually two years, March 1, 2007 through March 31, 2009.

Deep Drilling for ‘Black Smoker’ Clues

A project to learn more about extracting energy from hot rocks on land should give clues about “black smokers,” hydrothermal vents that belch superheated water and minerals deep below the ocean.

As part of the Iceland Deep Drilling Project, researchers from UC Davis, UC Riverside, Stanford University and the University of Oregon plan to sink a deep borehole into a site on land where seawater circulates through deep, hot rock. Most such sites on land have circulating fresh water, with very different chemistry.

“It’s the dry land version of a deep sea hydrothermal vent,” said Robert Zierenberg, professor of geology at UC Davis. Zierenberg and another geology professor, Peter Schiffman, are the UC Davis members of the research team. “It’s the first opportunity to look at rocks and fluid together and in situ.”

Deep ocean hydrothermal vents support unique communities of living things that, unlike most ecosystems on Earth, draw no energy from the sun. The vents also generate unusual, and possibly valuable, deposits of copper, zinc and other minerals.

Zierenberg said it is technically challenging to drill into rocks that are under high pressure and bathed in corrosive fluids at 450 degrees Celsius (840 degrees Fahrenheit), but it is easier than trying to drill deep below the sea floor in the deepest parts of the ocean.

The Iceland Deep Drilling Project is supported by the Icelandic power industry and government, in collaboration with U.S. government agencies. It aims to drill deep boreholes to learn more about processes in deep, hot rocks, with the goal of producing more energy from a single geothermal well. Iceland already gets half of its electrical power and meets much of its needs for space heating and hot water from geothermal energy.

The university research project is supported by grants from the National Science Foundation and the International Continental Drilling Program. The researchers expect to start drilling in the summer of 2008.

Yellowstone Rising

The orange shapes in this image represent the magma chamber -- a chamber of molten and partly molten rock -- beneath the giant volcanic crater known as the Yellowstone caldera, which is represented by the rusty-colored outline at the top. The red rectangular slab-like feature is a computer-generated representation of molten rock injected into the magma chamber since mid-2004, causing the caldera to rise at an unprecedented rate of almost 3 inches a year, according to a new University of Utah study. In reality, the injected magma probably is shaped more like a pancake than a slab. The two rusty circles within the caldera outline represent the resurgent volcanic domes above the magma chamber. - Photo Credit: Wu-Lung Chang
The orange shapes in this image represent the magma chamber — a chamber of molten and partly molten rock — beneath the giant volcanic crater known as the Yellowstone caldera, which is represented by the rusty-colored outline at the top. The red rectangular slab-like feature is a computer-generated representation of molten rock injected into the magma chamber since mid-2004, causing the caldera to rise at an unprecedented rate of almost 3 inches a year, according to a new University of Utah study. In reality, the injected magma probably is shaped more like a pancake than a slab. The two rusty circles within the caldera outline represent the resurgent volcanic domes above the magma chamber. – Photo Credit: Wu-Lung Chang

The Yellowstone “supervolcano” rose at a record rate since mid-2004, likely because a Los Angeles-sized, pancake-shaped blob of molten rock was injected 6 miles beneath the slumbering giant, University of Utah scientists report in the journal Science.

“There is no evidence of an imminent volcanic eruption or hydrothermal explosion. That’s the bottom line,” says seismologist Robert B. Smith, lead author of the study and professor of geophysics at the University of Utah. “A lot of calderas [giant volcanic craters] worldwide go up and down over decades without erupting.”

The upward movement of the Yellowstone caldera floor – almost 3 inches (7 centimeters) per year for the past three years – is more than three times greater than ever observed since such measurements began in 1923, says the study in the Nov. 9 issue of Science by Smith, geophysics postdoctoral associate Wu-Lung Chang and colleagues.

“Our best evidence is that the crustal magma chamber is filling with molten rock,” Smith says. “But we have no idea how long this process goes on before there either is an eruption or the inflow of molten rock stops and the caldera deflates again,” he adds.

The magma chamber beneath Yellowstone National Park is a not a chamber of molten rock, but a sponge-like body with molten rock between areas of hot, solid rock.

Chang, the study’s first author, says: “To say if there will be a magma [molten rock] eruption or hydrothermal [hot water] eruption, we need more independent data.”

Calderas such as Yellowstone, California’s Long Valley (site of the Mammoth Lakes ski area) and Italy’s Campi Flegrei (near Naples) huff upward and puff downward repeatedly for decades to tens of thousands of years without catastrophic eruptions.

Smith and Chang conducted the study with University of Utah geophysics doctoral students Jamie M. Farrell and Christine Puskas, and with geophysicist Charles Wicks, of the U.S. Geological Survey in Menlo Park, Calif.

Yellowstone: A Gigantic Volcano Atop a Hotspot

Yellowstone is North America’s largest volcanic field, produced by a “hotspot” – a gigantic plume of hot and molten rock – that begins at least 400 miles beneath Earth’s surface and rises to 30 miles underground, where it widens to about 300 miles across. There, blobs of magma or molten rock occasionally break off from the top of the plume, and rise farther, resupplying the magma chamber beneath the Yellowstone caldera. Previous research indicates the magma chamber begins about 5 miles beneath Yellowstone and extends down to a depth of at least 10 miles. Its heat powers Yellowstone’s geysers and hot springs – the world’s largest hydrothermal field.

As Earth’s crust moved southwest over the Yellowstone hotspot during the past 16.5 million years, it produced more than 140 cataclysmic explosions known as caldera eruptions, the largest but rarest volcanic eruptions known. Remnants of ancient calderas reveal the eruptions began at the Oregon-Idaho-Nevada border some 16.5 million years ago, then moved progressively northeast across what is now the Snake River Plain.

The hotspot arrived under the Yellowstone area sometime after about 4 million years ago, producing gargantuan eruptions there 2 million, 1.3 million and 642,000 years ago. These eruptions were 2,500, 280 and 1,000 times bigger, respectively, than the 1980 eruption of Mount St. Helens. The eruptions covered as much as half the continental United States with inches to feet of volcanic ash.

The most recent giant eruption created the 40-mile-by-25-mile oval-shaped Yellowstone caldera. The caldera walls have eroded away in many areas – although they remain visible in the northwest portion of the park. Yellowstone Lake sits roughly half inside and half outside the eroded caldera. Many smaller volcanic eruptions occurred at Yellowstone between and since the three big blasts, most recently 70,000 years ago. Smaller steam and hot water explosions have been more frequent and more recent.

Measuring a Volcano Getting Pumped Up

This digital elevation map of Yellowstone and Grand Teton national parks was overlaid with elevation change data (colors) from Global Positioning System receivers and satellite measurements. A University of Utah study of the data indicates the giant Yellowstone “supervolcano” is rising upward faster than ever observed. The red arrows pointing up represent uplift of the Yellowstone caldera, or volcanic crater, while the downward red arrows show sinking of the land near Norris Geyser Basin. The black arrows indicate lateral or horizontal ground movement. – Photo Credit: Wu-Lung Chang, University of Utah

In the new study, the scientists measured uplift of the Yellowstone caldera from July 2004 through the end of 2006 with two techniques:

  • Twelve Global Positioning System (GPS) ground stations that receive timed signals from satellites, making it possible to measure ground uplift precisely.
  • The European Space Agency’s Envisat satellite, which bounces radar waves off the Yellowstone caldera’s floor.

The measurements showed that from mid-2004 through 2006, the Yellowstone caldera floor rose as fast as 2.8 inches (7 centimeters) per year – and by a total of 7 inches (18 centimeters) during the 30-month period, Chang says.

“The uplift is still going on today but at a little slower rate,” says Smith, adding there is no way to know when it will stop.

Smith says the fastest rate of uplift previously observed at Yellowstone was about 0.8 inch (2 centimeters) per year between 1976 and 1985.

He says that Yellowstone’s recent upward motion may seem small, but is twice as fast as the average rate of horizontal movement along California’s San Andreas fault.

The current uplift is faster than ever observed at Yellowstone, but may not be the fastest ever, since humans weren’t around for its three supervolcano eruptions.

Chang, Smith and colleagues conducted computer simulations to determine what changes in shape of the underground magma chamber best explained the recent uplift.

The simulations or “modeling” suggested the molten rock injected since mid-2004 is a nearly horizontal slab – known to geologists as a sill – that rests about 6 miles (10 kilometers) beneath Yellowstone National Park. The slab sits within and near the top of the pre-existing magma chamber, which resembles two anvil-shaped blobs expanding upward from a common base.

Smith describes the slab’s computer-simulated shape as “kind of like a mattress” about 38 miles long and 12 miles wide, but only tens or hundreds of yards thick.

In reality, he believes the slab resembles a large, spongy pancake formed as molten rock injected from below spread out near the top of the magma chamber.

The pancake of molten rock has an area of about 463 square miles, compared with 469 square miles of land for the City of Los Angeles.

Smith and colleagues believe steam and hot water contribute to uplift of the Yellowstone caldera, particularly during some previous episodes, but evidence indicates molten rock is responsible for most of the current uplift.

Chang says that when rising molten rock reaches the top of the magma chamber, it starts to crystallize and solidify, releasing hot water and gases, pressuring the magma chamber. But gases and steam compress more easily than molten rock, so much greater volumes would be required to explain the volcano’s inflation, the researchers say.

Also, large volumes of steam and hot water usually are no deeper than 2 miles, so they are unlikely to be inflating the magma chamber 6 miles underground, Smith adds.

Ups and Downs at Yellowstone

Conventional surveying of Yellowstone began in 1923. Measurements showed the caldera floor rose 40 inches during 1923-1984, and then fell 8 inches during 1985-1995.

GPS data showed the Yellowstone caldera floor sank 4.4 inches during 1987-1995. From 1995 to 2000, the caldera rose again, but the uplift was greatest – 3 inches – at Norris Geyser Basin, just outside the caldera’s northwest rim.

During 2000-2003, the northwest area rose another 1.4 inches, but the caldera floor itself sank about 1.1 inches. The trend continued during the first half of 2004. Then, in July 2004, the caldera floor began its rapid rate of uplift, followed three months later by sinking of the Norris area that continued until mid-2006.

Smith believes that uplift of the middle of the caldera decreased pressure within rocks along the edges of the giant crater, “so it allowed fluids to flow into the area of increased porosity.” That, in turn, triggered small earthquakes along the edge of the “pancake” of magma. The amount of hot water flowing out of the deflated Norris area is much smaller than the volume of magma injected beneath the caldera, Smith says.

The research was funded by the National Science Foundation, the U.S. Geological Survey and the Brinson Foundation.

NEPTUNE Completes First Phase of Installation

The Ile de Sein is a vessel from project Neptune to establish a regional-scale ocean observatory in the northeast Pacific Ocean. It willl begin laying the Project's 3000-km network of fiber-optic/power cables on the ocean floor - Photo Credit: Lightgazer
The Ile de Sein is a vessel from project Neptune to establish a regional-scale ocean observatory in the northeast Pacific Ocean. It willl begin laying the Project’s 3000-km network of fiber-optic/power cables on the ocean floor – Photo Credit: Lightgazer

The first phase of the new NEPTUNE Canada ocean observatory is being completed today off the west coast of Vancouver Island.

The cable-laying vessel Ile de Sein returned last night to Port Alberni on the west coast of Vancouver Island after nine weeks at sea laying and partially burying 800 km of powered fibre-optic cable, repeaters, branching units and spur cables on the ocean floor.

The newly laid cable runs down Alberni Inlet and out into the open ocean in a large loop that extends across the continental shelf and lies as deep as 2,600 metres. In August, the first end of the cable loop was connected to the UVic shore station in Port Alberni. This morning, the other end of the cable was winched ashore, closing the loop.

The cable is the backbone of the North-East Pacific Time-series Undersea Networked Experiments, or NEPTUNE, the world’s first regional cabled ocean observatory. Led by the University of Victoria, NEPTUNE Canada will transform ocean science by transmitting data instantly to shore where they will be relayed to researchers, educational institutions and the public via the Internet.

The cable installation was supervised by Alcatel-Lucent, which, along with its subcontractors, is designing, manufacturing and installing much of NEPTUNE Canada’s equipment and technology.

“As expected, the installation of the cable was challenging at times, but thanks to the expertise of Alcatel-Lucent, everything went very well,” says Dr. Chris Barnes, project director of NEPTUNE Canada. “Alcatel-Lucent has now contracted another cable ship with a remotely operated vehicle to inspect sections of the cable route to ensure proper placement and burial.”

Following the inspection, the focus will shift to the second stage of installation-the deployment of five 6.5-tonne nodes at scientifically significant locations along the loop, scheduled for summer 2008.

The nodes will eventually support more than 200 interactive sampling instruments and sensors, as well as video cameras and a remotely operated vehicle, as they collect data and imagery from the ocean surface to beneath the seafloor. The first live data flow is targeted for late 2008.

“The successful completion of the cable installation demonstrates the importance of close working relationships between the scientific community, the NEPTUNE Canada project team and our industry partners,” says Peter Phibbs, associate director of engineering and operations for NEPTUNE Canada.

“We’ll be working through the winter with Alcatel-Lucent and a Vancouver company, OceanWorks, to finalize node and junction box technologies that are being developed for the first time, anywhere.”

NEPTUNE Canada spans much of the northern Juan de Fuca plate, permitting broad studies on such topics as seismic and tsunami activity, ocean-climate interactions and their effects on fisheries, gas hydrate deposits, and seafloor ecology. It will also promote new developments in marine technology, fibre-optic communications, power systems design, data management, and sensors and robotics.

The development and installation of the NEPTUNE Canada observatory and its technologies is funded by significant grants from the Canada Foundation for Innovation and the BC Knowledge Development Fund.

Climate Change Could Diminish Drinking Water More Than Expected

 Researchers at Ohio State University have simulated how saltwater intrudes into fresh water supplies along coastlines, and found that mixed, or brackish, water, can extend much farther inland than previously thought. In this image from the simulation, saltwater is red and fresh water is dark blue. The colors in between represent brackish water with different amounts of salt. Image by Jun Mizuno, courtesy of Ohio State University.
Researchers at Ohio State University have simulated how saltwater intrudes into fresh water supplies along coastlines, and found that mixed, or brackish, water, can extend much farther inland than previously thought. In this image from the simulation, saltwater is red and fresh water is dark blue. The colors in between represent brackish water with different amounts of salt. Image by Jun Mizuno, courtesy of Ohio State University.

As sea levels rise, coastal communities could lose up to 50 percent more of their fresh water supplies than previously thought, according to a new study from Ohio State University.

Hydrologists here have simulated how saltwater will intrude into fresh water aquifers, given the sea level rise predicted by the Intergovernmental Panel on Climate Change (IPCC). The IPCC has concluded that within the next 100 years, sea level could rise as much as 23 inches, flooding coasts worldwide.

Scientists previously assumed that, as saltwater moved inland, it would penetrate underground only as far as it did above ground.

But this new research shows that when saltwater and fresh water meet, they mix in complex ways, depending on the texture of the sand along the coastline. In some cases, a zone of mixed, or brackish, water can extend 50 percent further inland underground than it does above ground.

Like saltwater, brackish water is not safe to drink because it causes dehydration. Water that contains less than 250 milligrams of salt per liter is considered fresh water and safe to drink.

Motomu Ibaraki, associate professor of earth sciences at Ohio State, led the study. Graduate student Jun Mizuno presented the results Tuesday, October 30, 2007, at the Geological Society of America meeting in Denver.

“Most people are probably aware of the damage that rising sea levels can do above ground, but not underground, which is where the fresh water is,” Ibaraki said. “Climate change is already diminishing fresh water resources, with changes in precipitation patterns and the melting of glaciers. With this work, we are pointing out another way that climate change can potentially reduce available drinking water. The coastlines that are vulnerable include some of the most densely populated regions of the world.”

In the United States, lands along the East Coast and the Gulf of Mexico — especially Florida and Louisiana — are most likely to be flooded as sea levels rise. Vulnerable areas worldwide include Southeast Asia, the Middle East, and northern Europe.

“Almost 40 percent of the world population lives in coastal areas, less than 60 kilometers from the shoreline,” Mizuno said. “These regions may face loss of freshwater resources more than we originally thought.”

Scientists have used the IPCC reports to draw maps of how the world’s coastlines will change as waters rise, and they have produced some of the most striking images of the potential consequences of climate change.

Ibaraki said that he would like to create similar maps that show how the water supply could be affected.

That’s not an easy task, since scientists don’t know exactly where all of the world’s fresh water is located, or how much is there. Nor do they know the details of the subterranean structure in many places.

One finding of this study is that saltwater will penetrate further into areas that have a complex underground structure.

Typically, coastlines are made of different sandy layers that have built up over time, Ibaraki explained. Some layers may contain coarse sand and others fine sand. Fine sand tends to block more water, while coarse sand lets more flow through.

The researchers simulated coastlines made entirely of coarse or fine sand, and different textures in between. They also simulated more realistic, layered underground structures.

The simulation showed that, the more layers a coastline has, the more the saltwater and fresh water mix. The mixing causes convection — similar to the currents that stir water in the open sea. Between the incoming saltwater and the inland fresh water, a pool of brackish water forms.

Further sea level rise increases the mixing even more.

Depending on how these two factors interact, underground brackish water can extend 10 to 50 percent further inland than the saltwater on the surface.

According to the United States Geological Survey, about half the country gets its drinking water from groundwater. Fresh water is also used nationwide for irrigating crops.

“In order to obtain cheap water for everybody, we need to use groundwater, river water, or lake water,” Ibaraki said. “But all those waters are disappearing due to several factors –including an increase in demand and climate change.”

One way to create more fresh water is to desalinate saltwater, but that’s expensive to do, he said.

“To desalinate, we need energy, so our water problem would become an energy problem in the future.”

Scientists help map Antarctic ice sheets

Newcastle University scientists are joining the race to discover how climate change is affecting Antarctic ice sheets.

Researcher David Barber will spend four months installing GPS signal receivers on two huge plateaus of ice that cover the sea, so that their movements can be monitored by satellite.

These measurements will enable other members of the project team in Newcastle, led by Dr Matt King (pictured), to calculate how much the ice sheets rise and fall with the tides. This will pave the way for much more accurate measurements of the thickness of the ice sheets, so that scientists will know whether and how fast the ice is melting.

David flies out to west Antarctica on 6 November and over the next few weeks will plant about 15 receivers on the vast Ronne ice shelf, which is about the same size as France.

He will then plant receivers on the smaller Larsen ice sheet, which featured in the opening scenes of the climate change disaster movie, The Day After Tomorrow, in which Hollywood special effects made it appear as if the ice sheet cracked as it was being drilled.

Matt said: ‘The Larsen sheet is quite famous because a couple of years ago, a chunk about half the size of Cumbria and a few hundred metres thick broke off in a matter of days – you could say that the real life scenario has exceeded Hollywood’s expectations!’

As a result, there was a very small increase in sea level, but scientists need to know the condition of the ice sheet across its whole expanse, said Matt.

‘Satellite measurements have helped us make great progress in mapping the entire ice sheet, but we still don’t actually know how quickly the ice sheets are melting, if at all, but it is important that we find out and monitor the situation so that we can anticipate any rise in sea level.

‘The tides are very large in this part of the world – perhaps eight to ten metres – and we need to know how this affects the ice sheets lying on top of the sea before we can measure their thickness.

The research project is being carried out by the School of Civil Engineering and Geosciences at Newcastle University and is being funded by the Natural Environment Research Council. Support for the project is being provided by the British Antarctic Survey and the Earth and Space Research organisation, Oregon, USA.

Once the effects of the tides have been taken into account, the picture will be much clearer. Upwards movement will mean a thickening of the ice and downwards thinning. Seasonal variations are normal but scientists will be looking for long-term changes.

David said: ‘Using satellites, we can now measure any movement on the Earth’s surface to an accuracy of a few millimetres. This is a very good way to measure small annual changes in the thickness of ice but you have to know about other movements, such as those caused by tides, first.’

David, who lives in North Shields, will fly out from RAF from Brize Norton in Oxfordshire to the Ascension Islands and then on to the Falklands. From there, he will fly to the British Antarctic Survey base at Rothera, in West Antarctica.

Staff from the Survey base will assist David on his project, which will involve flying to various points on the two ice shelves and installing the receivers, along with solar panels and wind turbine generators to power them.

David expects to be in the Antarctic until February. Because it will be the summer time, temperatures at the base are likely to be only a few degrees below freezing point, although temperatures as low as -20C are possible on the inner edge of the Ronne ice shelf. A few of the GPS receivers will be left for the winter to be retrieved the following Antarctic summer, experiencing temperatures perhaps as low as -40C in the winter.

Western Canada’s Glaciers Hit 7000-Year Low

Overlord Glacier - 7000 years old. glacier in background.
Overlord Glacier – 7000 years old. glacier in background.

Tree stumps at the feet of Western Canadian glaciers are providing new insights into the accelerated rates at which the rivers of ice have been shrinking due to human-aided global warming.

Geologist Johannes Koch of The College of Wooster found the deceptively fresh and intact tree stumps beside the retreating glaciers of Garibaldi Provincial Park, about 40 miles (60 km) north of Vancouver, British Columbia. What he wanted to know was how long ago the glaciers made their first forays into a long-lost forest to kill the trees and bury them under ice.

To find out, Koch radiocarbon-dated wood from the stumps to see how long they have been in cold storage. The result was a surprising 7000 years.

“The stumps were in very good condition sometimes with bark preserved,” said Koch, who conducted the work as part of his doctoral thesis at Simon Fraser University in Burnaby, British Columbia. Koch will present his results on Wednesday, 31 October 2007, at the Geological Society of America Annual Meeting in Denver.

The pristine condition of the wood, he said, can best be explained by the stumps having spent all of the last seven millennia under tens to hundreds of meters of ice. All stumps were still rooted to their original soil and location.

“Thus they really indicate when the glaciers overrode them, and their kill date gives the age of the glacier advance,” Koch explained. They also give us a span of time during which the glaciers have always been larger than they were 7000 years ago — until the recently warming climate released the stumps from their icy tombs.

Koch compared the kill dates of the trees in the southern and northern Coast Mountains of British Columbia and those in the mid- and southern Rocky Mountains in Canada to similar records from the Yukon Territory, the European Alps, New Zealand and South America. He also looked at the age of Oetzi, the prehistoric mummified alpine “Iceman” found at Niederjoch Glacier, and similarly well-preserved wood from glaciers and snowfields in Scandinavia.

The radiocarbon dates seem to be the same around the world, according to Koch. It’s important to note that there have been many advances and retreats of these glaciers over the past 7000 years, but no retreats that have pushed them back so far upstream as to expose these trees.

The age of the tree stumps gives new emphasis to the well-documented “before” and “after” photographs of retreating glaciers during the 20th century.

“It seems like an unprecedented change in a short amount of time,” Koch said. “From this work and many other studies looking at forcings of the climate system, one has to turn away from natural ones alone to explain this dramatic change of the past 150 years.”

Researchers find origin of ‘breathable’ atmosphere half a billion years ago

Ohio State University geologists and their colleagues have uncovered evidence of when Earth may have first supported an oxygen-rich atmosphere similar to the one we breathe today.

The study suggests that upheavals in the earth’s crust initiated a kind of reverse-greenhouse effect 500 million years ago that cooled the world’s oceans, spawned giant plankton blooms, and sent a burst of oxygen into the atmosphere.

That oxygen may have helped trigger one of the largest growths of biodiversity in Earth’s history.

Matthew Saltzman, associate professor of earth sciences at Ohio State, reported the findings Sunday at the meeting of the Geological Society of America in Denver .

For a decade, he and his team have been assembling evidence of climate change that occurred 500 million years ago, during the late Cambrian period. They measured the amounts of different chemicals in rock cores taken from around the world, to piece together a complex chain of events from the period.

Their latest measurements, taken in cores from the central United States and the Australian outback, revealed new evidence of a geologic event called the Steptoean Positive Carbon Isotope Excursion (SPICE).

Amounts of carbon and sulfur in the rocks suggest that the event dramatically cooled Earth’s climate over two million years — a very short time by geologic standards. Before the event, the Earth was a hothouse, with up to 20 times more carbon dioxide in the atmosphere compared to the present day. Afterward, the planet had cooled and the carbon dioxide had been replaced with oxygen. The climate and atmospheric composition would have been similar to today.

“If we could go back in time and walk around in the late Cambrian, this seems to be the first time we would have felt at home,” Saltzman said. “Of course, there was no life on land at the time, so it wouldn’t have been all that comfortable.”

The land was devoid of plants and animals, but there was life in the ocean, mainly in the form of plankton, sea sponges, and trilobites. Most of the early ancestors of the plants and animals we know today existed during the Cambrian, but life wasn’t very diverse.

Then, during the Ordovician period, which began around 490 million years ago, many new species sprang into being. The first coral reefs formed during that time, and the first true fish swam among them. New plants evolved and began colonizing land.

“If you picture the evolutionary “tree of life,’ most of the main branches existed during the Cambrian, but most of the smaller branches didn’t get filled in until the Ordovician,” Saltzman said. “That’s when animal life really began to develop at the family and genus level.” Researchers call this diversification the “Ordovician radiation.”

The composition of the atmosphere has changed many times since, but the pace of change during the Cambrian is remarkable. That’s why Saltzman and his colleagues refer to this sudden influx of oxygen during the SPICE event as a “pulse” or “burst.”

“After this pulse of oxygen, the world remained in an essentially stable, warm climate, until late in the Ordovician,” Saltzman said.

He stopped short of saying that the oxygen-rich atmosphere caused the Ordovician radiation.

“We know that oxygen was released during the SPICE event, and we know that it persisted in the atmosphere for millions of years — during the time of the Ordovician radiation — so the timelines appear to match up. But to say that the SPICE event triggered the diversification is tricky, because it’s hard to tell exactly when the diversification started,” he said.

“We would need to work with paleobiologists who understand how increased oxygen levels could have led to a diversification. Linking the two events precisely in time is always going to be difficult, but if we could link them conceptually, then it would become a more convincing story.”

Researchers have been trying to understand the sudden climate change during the Cambrian period ever since Saltzman found the first evidence of the SPICE event in rock in the American west in 1998. Later, rock from a site in Europe bolstered his hypothesis, but these latest finds in central Iowa and Queensland, Australia, prove that the SPICE event occurred worldwide.

During the Cambrian period, most of the continents as we know them today were either underwater or part of the Gondwana supercontinent, Saltzman explained. Tectonic activity was pushing new rock to the surface, where it was immediately eaten away by acid rain. Such chemical weathering pulls carbon dioxide from the air, traps the carbon in sediments, and releases oxygen — a kind of greenhouse effect in reverse.

“From our previous work, we knew that carbon was captured and oxygen was released during the SPICE event, but we didn’t know for sure that the oxygen stayed in the atmosphere,” Saltzman said.

They compared measurements of inorganic carbon — captured during weathering — with organic carbon — produced by plankton during photosynthesis. And because plankton contain different ratios of the isotopes of carbon depending on the amount of oxygen in the air, the geologists were able to double-check their estimates of how much oxygen was released during the period, and how long it stayed in the atmosphere.

They also studied isotopes of sulfur, to determine whether much of the oxygen being produced was re-captured by sediments.

It wasn’t.

Saltzman explained the chain of events this way: Tectonic activity led to increased weathering, which pulled carbon dioxide from the air and cooled the climate. Then, as the oceans cooled to more hospitable temperatures, the plankton prospered — and in turn created more oxygen through photosynthesis.

“It was a double whammy,” he said. “There’s really no way around it when we combine the carbon and sulfur isotope data — oxygen levels dramatically rose during that time.”

What can this event tell us about climate change today? “Oxygen levels have been stable for the last 50 million years, but they have fluctuated over the last 500 million,” Saltzman said. “We showed that the oxygen burst in the late Cambrian happened over only two million years, so that is an indication of the sensitivity of the carbon cycle and how fast things can change.”

Global cooling may have boosted life early in the Ordovician period, but around 450 million years ago, more tectonic activity — most likely, the rise of the Appalachian Mountains — brought on a deadly ice age. So while most of the world’s plant and animal species were born during the Ordovician period, by the end of it, more than half of them had gone extinct.

Coauthors on this study included Seth Young, a graduate student in earth sciences at Ohio State; Ben Gill, a graduate student, and Tim Lyons, professor of earth sciences, both at the University of California, Riverside; Lee Kump, professor of geosciences at Penn State University; and Bruce Runnegar, professor of paleontology at the University of California, Los Angeles.