The year of the Alaska volcano: Eruptions keep observatory busy

Three Alaska volcanoes erupted in midsummer 2008. Cleveland, Okmok and Kasatochi volcanoes, all located in Alaska’s Aleutian Chain, made for a hectic 20th anniversary for the Alaska Volcano Observatory.

Scientists from AVO and the Geophysical Institute at the University of Alaska Fairbanks will share details of their research on North Pacific volcanoes, highlighting some of the recent volcanic eruptions in Alaska, at a variety of presentations at the American Geophysical Union’s fall meeting in San Francisco, Dec. 15-19, 2008.

Geophysical Institute director Roger Smith will present on the history and achievements of the Alaska Volcano Observatory on Thursday, Dec. 18. Smith’s talk will cover the observatory’s first test that occurred with the 1989 eruption of Redoubt Volcano. The eruption spewed ash to a height of 45,000 feet, jeopardizing a Boeing 747 aircraft that was in range and covering Alaska’s Kenai Peninsula with ash. Smith’s talk begins at 3:25 p.m. in Moscone Center West, Room 3003.

Jessica Larsen, a research assistant professor with the Geophysical Institute and the UAF College of Natural Science and Mathematics, will talk on the eruption of Okmok Volcano, located near Dutch Harbor, Alaska. Okmok erupted explosively July 12, 2008 considerably changing the surrounding landscape Larsen had worked on for years. Larsen will share images from her pre- and post-eruption visits to Okmok during her presentation on Friday, Dec. 19 at 8:30 a.m. in Moscone Center West, Room 2011.

Smith and Larsen are just two of many presenters from the University of Alaska Fairbanks who will focus on the advances of the Alaska Volcano Observatory and the 2008 eruptions of Cleveland, Okmok and Kasatochi volcanoes. Other talks and poster sessions will focus on AVO instrumentation, volcano seismology, volcanic infrasound, computer simulations of volcanic ash, and more.

Study: Did early climate impact divert a new glacial age?

The common wisdom is that the invention of the steam engine and the advent of the coal-fueled industrial age marked the beginning of human influence on global climate.

But gathering physical evidence, backed by powerful simulations on the world’s most advanced computer climate models, is reshaping that view and lending strong support to the radical idea that human-induced climate change began not 200 years ago, but thousands of years ago with the onset of large-scale agriculture in Asia and extensive deforestation in Europe.

What’s more, according to the same computer simulations, the cumulative effect of thousands of years of human influence on climate is preventing the world from entering a new glacial age, altering a clockwork rhythm of periodic cooling of the planet that extends back more than a million years.

“This challenges the paradigm that things began changing with the Industrial Revolution,” says Stephen Vavrus, a climatologist at the University of Wisconsin-Madison’s Center for Climatic Research and the Nelson Institute for Environmental Studies. “If you think about even a small rate of increase over a long period of time, it becomes important.”

Addressing scientists here today (Dec. 17) at a meeting of the American Geophysical Union, Vavrus and colleagues John Kutzbach and Gwena�lle Philippon provided detailed evidence in support of a controversial idea first put forward by climatologist William F. Ruddiman of the University of Virginia. That idea, debated for the past several years by climate scientists, holds that the introduction of large-scale rice agriculture in Asia, coupled with extensive deforestation in Europe began to alter world climate by pumping significant amounts of greenhouse gases – methane from terraced rice paddies and carbon dioxide from burning forests – into the atmosphere. In turn, a warmer atmosphere heated the oceans making them much less efficient storehouses of carbon dioxide and reinforcing global warming.

That one-two punch, say Kutzbach and Vavrus, was enough to set human-induced climate change in motion.

“No one disputes the large rate of increase in greenhouse gases with the Industrial Revolution,” Kutzbach notes. “The large-scale burning of coal for industry has swamped everything else” in the record.

But looking farther back in time, using climatic archives such as 850,000-year-old ice core records from Antarctica, scientists are teasing out evidence of past greenhouse gases in the form of fossil air trapped in the ice. That ancient air, say Vavrus and Kutzbach, contains the unmistakable signature of increased levels of atmospheric methane and carbon dioxide beginning thousands of years before the industrial age.

“Between 5,000 and 8,000 years ago, both methane and carbon dioxide started an upward trend, unlike during previous interglacial periods,” explains Kutzbach. Indeed, Ruddiman has shown that during the latter stages of six previous interglacials, greenhouse gases trended downward, not upward. Thus, the accumulation of greenhouse gases over the past few thousands of years, the Wisconsin-Virginia team argue, is very likely forestalling the onset of a new glacial cycle, such as have occurred at regular 100,000-year intervals during the last million years. Each glacial period has been paced by regular and predictable changes in the orbit of the Earth known as Milankovitch cycles, a mechanism thought to kick start glacial cycles.

“We’re at a very favorable state right now for increased glaciation,” says Kutzbach. “Nature is favoring it at this time in orbital cycles, and if humans weren’t in the picture it would probably be happening today.”

Importantly, the new research underscores the key role of greenhouse gases in influencing Earth’s climate. Whereas decreasing greenhouse gases in the past helped initiate glaciations, the early agricultural and recent industrial increases in greenhouse gases may be forestalling them, say Kutzbach and Vavrus.

Using three different climate models and removing the amount of greenhouse gases humans have injected into the atmosphere during the past 5,000 to 8,000 years, Vavrus and Kutzbach observed more permanent snow and ice cover in regions of Canada, Siberia, Greenland and the Rocky Mountains, all known to be seed regions for glaciers from previous ice ages. Vavrus notes: “With every feedback we’ve included, it seems to support the hypothesis (of a forestalled ice age) even more. We keep getting the same answer.”

Researchers use satellites to measure inland floods

Satellites that were designed to measure sea level over the world’s oceans can serve a valuable purpose over land, a new study has found.

Researchers used NASA’s TOPEX/Poseidon satellite and the European Space Agency’s ENVISAT satellite to measure the height and extent of flooding in North America, South America, and Asia.

The study shows that satellites can supplement the measurements that the United States Geological Survey (USGS) gathers from flood gauges on the ground — at little or no cost, said C.K. Shum, professor of earth sciences at Ohio State University.

“After a flood, we can look back at the satellite data to pinpoint when the flood began, and find out how far the flood waters extended, which is really important for flood modeling,” he said.

Satellites such as TOPEX/Poseidon measure the height of land or water by bouncing radio signals off of surfaces and measuring how long the signals take to return. Rough surfaces scatter some of the signal in other directions, and cause errors in a satellite’s on board tracking system. This often happens over land. Scientists use “re-tracking” software to fix the errors, and make the satellite’s measurements more precise.

That’s what the Ohio State software does — it re-tracks the satellite data, but in a way that enables detailed measurements of water on land.

The key to the software is an algorithm that can tell the difference between water and snow cover. Ohio State postdoctoral researcher Hyongki Lee developed the algorithm and graduate student Manman Zhang applied the algorithm for her doctoral thesis.

Zhang presented the work in a poster session at the American Geophysical Union meeting in San Francisco.

Shum, Zhang, and their colleagues used the software to process TOPEX/Poseidon data from the 1997 Red River flood in the upper Midwest of the United States, an area with abundant farmland and wetlands. They detected flooded regions within four river basins: the Red River Basin in North Dakota and Minnesota; the Missouri River Basin in North Dakota and South Dakota; and the Minnesota River Basin and the Mississippi River Basin, both in Minnesota and Iowa.

The flood happened in April of that year, as winter snows began to melt. Zhang’s algorithm differentiated between the scattered radar signal produced by water and by areas still covered by snow. As the floodwaters began to move down the Red River, the satellite measurements provided estimates of flood levels.

After re-tracking, the satellite data agreed with USGS ground measurements taken at the time. For example, the software determined that flood waters in Grand Forks, North Dakota, rose 20 feet (6 meters), which matched data recorded from flood gauges there.

The researchers did the same for the June 2008 Iowa City flood that killed three people and damaged 2 million acres of farmland. They found that they could track the ebb and flow of that flood over a scale of several hours. For that part of the study, they worked with Carrie Huitger, a USGS hydrologist who supplied the flood gauge data.

They performed similar studies with TOPEX/Poseidon data for a flood in the Amazon River Basin, and with ENVISAT data for a flood in southwestern Taiwan — both with similar results.

The satellites can’t be used to forecast a flood because the data isn’t processed very quickly and the spatial coverage of the satellite measurements is limited, Shum explained. Even preliminary processing takes hours. But after a flood, such data can add to data collected on the ground, to help scientists better understand how floods happen.

Next, the researchers want to automate the software so that it can build an archive of flood data. Since the satellites are already in orbit collecting the data, there would be little cost beyond building the database and enabling scientists to access it.

In the future, a new satellite may enable more extensive and detailed measurements. Ohio State scientists lead an international team that has proposed the Surface Water Ocean Topography (SWOT) mission. The SWOT satellite will feature dual antennas that will gather high-resolution data over a much wider surface of the earth than is possible with today’s satellites.

New World post-pandemic reforestation helped start Little Ice Age

The power of viruses is well documented in human history. Swarms of little viral Davids have repeatedly laid low the great Goliaths of human civilization, most famously in the devastating pandemics that swept the New World during European conquest and settlement.

In recent years, there has been growing evidence for the hypothesis that the effect of the pandemics in the Americas wasn’t confined to killing indigenous peoples. Global climate appears to have been altered as well.

Stanford University researchers have conducted a comprehensive analysis of data detailing the amount of charcoal contained in soils and lake sediments at the sites of both pre-Columbian population centers in the Americas and in sparsely populated surrounding regions. They concluded that reforestation of agricultural lands-abandoned as the population collapsed-pulled so much carbon out of the atmosphere that it helped trigger a period of global cooling, at its most intense from approximately 1500 to 1750, known as the Little Ice Age.

“We estimate that the amount of carbon sequestered in the growing forests was about 10 to 50 percent of the total carbon that would have needed to come out of the atmosphere and oceans at that time to account for the observed changes in carbon dioxide concentrations,” said Richard Nevle, visiting scholar in the Department of Geological and Environmental Sciences at Stanford. Nevle and Dennis Bird, professor in geological and environmental sciences, presented their study at the annual meeting of the American Geophysical Union on Dec. 17, 2008.

Nevle and Bird synthesized published data from charcoal records from 15 sediment cores extracted from lakes, soil samples from 17 population centers and 18 sites from the surrounding areas in Central and South America. They examined samples dating back 5,000 years.

What they found was a record of slowly increasing charcoal deposits, indicating increasing burning of forestland to convert it to cropland, as agricultural practices spread among the human population-until around 500 years ago: At that point, there was a precipitous drop in the amount of charcoal in the samples, coinciding with the precipitous drop in the human population in the Americas.

To verify their results, they checked their fire histories based on the charcoal data against records of carbon dioxide concentrations and carbon isotope ratios that were available.

“We looked at ice cores and tropical sponge records, which give us reliable proxies for the carbon isotope composition of atmospheric carbon dioxide. And it jumped out at us right away,” Nevle said. “We saw a conspicuous increase in the isotope ratio of heavy carbon to light carbon. That gave us a sense that maybe we were looking at the right thing, because that is exactly what you would expect from reforestation.”

During photosynthesis, plants prefer carbon dioxide containing the lighter isotope of carbon. Thus a massive reforestation event would not only decrease the amount of carbon dioxide in the atmosphere, but would also leave carbon dioxide in the atmosphere that was enriched in the heavy carbon isotope.

Other theories have been proposed to account for the cooling at the time of the Little Ice Age, as well as the anomalies in the concentration and carbon isotope ratios of atmospheric carbon dioxide associated with that period.

Variations in the amount of sunlight striking the Earth, caused by a drop in sunspot activity, could also be a factor in cooling down the globe, as could a flurry of volcanic activity in the late 16th century.

But the timing of these events doesn’t fit with the observed onset of the carbon dioxide drop. These events don’t begin until at least a century after carbon dioxide in the atmosphere began to decline and the ratio of heavy to light carbon isotopes in atmospheric carbon dioxide begins to increase.

Nevle and Bird don’t attribute all of the cooling during the Little Ice Age to reforestation in the Americas.

“There are other causes at play,” Nevle said. “But reforestation is certainly a first-order contributor.”

Strange travels

Transport phenomena in highly heterogeneous media can be dramatically different from those in homogeneous media and therefore are of great fundamental and practical interest. Anomalous transport occurs in semiconductor physics, plasma physics, astrophysics, biology, and other areas. It plays an especially important role in hydrogeology because it may govern the rate of migration and degree of dispersion of groundwater contaminants from hazardous waste sites.

A series of four articles in Special Section: Nonclassical Transport of the November 2008 issue of Vadose Zone Journal is devoted to transport phenomena in heterogeneous media in the context of geologic disposal of radioactive waste. Guest Editors Leonid Bolshov and Peter Kondratenko (Nuclear Safety Institute, Russian Academy of Sciences) and Karsten Pruess (Lawrence Berkeley National Lab.) assembled the articles, which are the results of joint investigations performed at the Nuclear Safety Institute of the Russian Academy of Sciences and Lawrence Berkeley National Laboratory in California. The work was supported by the USDOE.

The problems addressed in this research involve a broad range of space and time scales and were approached using modern methods of theoretical and computational physics, such as scaling analysis and diagrammatic techniques used before in critical phenomena theory. Special attention is paid to concentration tails. This issue is exceptionally important for the reliability assessments of radioactive waste disposal because, depending on the structure of the tails, concentrations at large distances from the source can differ by many orders of magnitude.

The first paper of this special section presents an overview of field and laboratory observations that demonstrate nonclassical flow and transport behavior in geologic media, with an emphasis on the fractal geometry of natural fracture networks and the presence of contaminant traps. The second paper is devoted to the analysis of diffusion in heterogeneous media with sharply contrasting properties; the authors show that as time progresses, three different transport regimes can be realized. In the third paper, it is shown that the solute transport regime is determined by a competition of two mechanisms: random advection through a fracture network and trapping caused by sharply contrasting properties of the medium. In the fourth paper, the authors develop a model of anomalous diffusion to simulate solute transport in highly heterogeneous media, and the new model is shown to result in reasonable agreement with experimental data on solute transport in highly heterogeneous media.

Ancient magma ‘superpiles’ may have shaped the continents

Researchers have linked two giant plumes of hot rock deep within the earth to the plate motions that shape the continents. This new drawing of Earth's interior is based on one originally developed by study co-author Louise C. Kellogg of the University of California, Davis and her colleagues in 1999. A giant plume of hot rock called a 'superpile' (orange) sits atop Earth's core (red), while the remnants of two subducted continental plates (blue) sink down on either side of it. A magma plume (orange with red outline) can be seen rising from the superpile to the surface as a hotspot that creates island chains such as Hawaii. -  Image by the Cooperative Institute for Deep Earth Research (CIDER) collaboration, courtesy of Ohio State University.
Researchers have linked two giant plumes of hot rock deep within the earth to the plate motions that shape the continents. This new drawing of Earth’s interior is based on one originally developed by study co-author Louise C. Kellogg of the University of California, Davis and her colleagues in 1999. A giant plume of hot rock called a ‘superpile’ (orange) sits atop Earth’s core (red), while the remnants of two subducted continental plates (blue) sink down on either side of it. A magma plume (orange with red outline) can be seen rising from the superpile to the surface as a hotspot that creates island chains such as Hawaii. – Image by the Cooperative Institute for Deep Earth Research (CIDER) collaboration, courtesy of Ohio State University.

Two giant plumes of hot rock deep within the earth are linked to the plate motions that shape the continents, researchers have found.

The two superplumes, one beneath Hawaii and the other beneath Africa, have likely existed for at least 200 million years, explained Wendy Panero, assistant professor of earth sciences at Ohio State University.

The giant plumes — or “superpiles” as Panero calls them — rise from the bottom of Earth’s mantle, just above our planet’s core. Each is larger than the continental United States. And each is surrounded by a wall of plates from Earth’s crust that have sunk into the mantle.

She and her colleagues reported their findings at the American Geophysical Union meeting in San Francisco.

Computer models have connected the piles to the sunken former plates, but it’s currently unclear which one spawned the other, Panero said. Plates sink into the mantle as part of the normal processes that shape the continents. But which came first, the piles or the plates, the researchers simply do not know.

“Do these superpiles organize plate motions, or do plate motions organize the superpiles? I don’t know if it’s truly a chicken-or-egg kind of question, but the locations of the two piles do seem to be related to where the continents are today, and where the last supercontinent would have been 200 million years ago,” she said.

That supercontinent was Pangea, and its breakup eventually led to the seven continents we know today.

Scientists first proposed the existence of the superpiles more than a decade ago. Earthquakes offer an opportunity to study them, since they slow the seismic waves that pass through them. Scientists combine the seismic data with what they know about Earth’s interior to create computer models and learn more.

But to date, the seismic images have created a mystery: they suggest that the superpiles have remained in the same locations, unchanged for hundreds of millions of years.

“That’s a problem,” Panero said. “We know that the rest of the mantle is always moving. So why are the piles still there?”

Hot rock constantly migrates from the base of the mantle up to the crust, she explained. Hot portions of the mantle rise, and cool portions fall. Continental plates emerge, then sink back into the earth.

But the presence of the superpiles and the location of subducted plates suggest that the two superpiles have likely remained fixed to the Earth’s core while the rest of the mantle has churned around them for millions of years.

Unlocking this mystery is the goal of the Cooperative Institute for Deep Earth Research (CIDER) collaboration, a group of researchers from across the United States who are attempting to unite many different disciplines in the study of Earth’s interior.

Panero provides CIDER her expertise in mineral physics; others specialize in geodynamics, geomagnetism, seismology, and geochemistry. Together, they have assembled a new model that suggests why the two superpiles are so stable, and what they are made of.

As it turns out, just a tiny difference in chemical composition can keep the superpiles in place, they found.

The superpiles contain slightly more iron than the rest of the mantle; their composition likely consists of 11-13 percent iron instead of 10-12 percent. But that small change is enough to make the superpiles denser than their surroundings.

“Material that is more dense is going to sink to the base of the mantle,” Panero said. “It would normally spread out at that point, but in this case we have subducting plates that are coming down from above and keeping the piles contained.”

CIDER will continue to explore the link between the superpiles and the plates that surround them. The researchers will also work to explain the relationship between the superpiles and other mantle plumes that rise above them, which feed hotspots such as those beneath Hawaii and mid-ocean ridges. Ultimately, they hope to determine whether the superpiles may have contributed to the breakup of Pangea.

As ice melts, Antarctic bedrock is on the move

Eric Kendrick, a senior research associate at Ohio State, shown at a POLENET GPS site in West Antarctica.  He is standing in front of solar panels, battery boxes, and wind generators used to power the GPS station. -  Photo courtesy of Ohio State University
Eric Kendrick, a senior research associate at Ohio State, shown at a POLENET GPS site in West Antarctica. He is standing in front of solar panels, battery boxes, and wind generators used to power the GPS station. – Photo courtesy of Ohio State University

As ice melts away from Antarctica, parts of the continental bedrock are rising in response — and other parts are sinking, scientists have discovered.

The finding will give much needed perspective to satellite instruments that measure ice loss on the continent, and help improve estimates of future sea level rise.

“Our preliminary results show that we can dramatically improve our estimates of whether Antarctica is gaining or losing ice,” said Terry Wilson, associate professor of earth sciences at Ohio State University.

Wilson reported the research in a press conference Monday, December 15, 2008 at the American Geophysical Union meeting in San Francisco.

These results come from a trio of global positioning system (GPS) sensor networks on the continent.

Wilson leads POLENET, a growing network of GPS trackers and seismic sensors implanted in the bedrock beneath the West Antarctic Ice Sheet (WAIS). POLENET is reoccupying sites previously measured by the West Antarctic GPS Network (WAGN) and the Transantarctic Mountains Deformation (TAMDEF) network.

In separate sessions at the meeting, Michael Bevis, Ohio Eminent Scholar in geodyamics and professor of earth sciences at Ohio State, presented results from WAGN, while doctoral student Michael Willis presented results from TAMDEF.

Taken together, the three projects are yielding the best view yet of what’s happening under the ice.

When satellites measure the height of the WAIS, scientists calculate ice thickness by subtracting the height of the earth beneath it. They must take into account whether the bedrock is rising or falling. Ice weighs down the bedrock, but as the ice melts, the earth slowly rebounds.

Gravity measurements, too, rely on knowledge of the bedrock. As the crust under Antarctica rises, the mantle layer below it flows in to fill the gap. That mass change must be subtracted from Gravity Recovery and Climate Experiment (GRACE) satellite measurements in order to isolate gravity changes caused by the thickening or thinning of the ice.

Before POLENET and its more spatially limited predecessors, scientists had few direct measurements of the bedrock. They had to rely on computer models, which now appear to be incorrect.

“When you compare how fast the earth is rising, and where, to the models of where ice is being lost and how much is lost — they don’t match,” Wilson said. “There are places where the models predict no crustal uplift, where we see several millimeters of uplift per year. We even have evidence of other places sinking, which is not predicted by any of the models.”

A few millimeters may sound like a small change, but it’s actually quite large, she explained. Crustal uplift in parts of North America is measured on the scale of millimeters per year.

POLENET’s GPS sensors measure how much the crust is rising or falling, while the seismic sensors measure the stiffness of the bedrock — a key factor for predicting how much the bedrock will rise in the future.

“We’re pinning down both parts of this problem, which will improve the correction made to the satellite data, which will in turn improve what we know about whether we’re gaining ice or losing ice,” Wilson said. Better estimates of sea level rise can then follow.

POLENET scientists have been implanting sensors in Antarctica since December 2007. The network will be complete in 2010 and will record data into 2012. Selected sites may remain as a permanent Antarctic observational network.

Greenland’s glaciers losing ice faster this year than last year, which was record-setting itself

Researchers watching the loss of ice flowing out from the giant island of Greenland say that the amount of ice lost this summer is nearly three times what was lost one year ago.

The loss of floating ice in 2008 pouring from Greenland’s glaciers would cover an area twice the size of Manhattan Island in the U.S., they said.

Jason Box, an associate professor of geography at Ohio State, said that the loss of ice since the year 2000 is 355.4 square miles (920.5 square kilometers), or more than 10 times the size of Manhattan.

“We now know that the climate doesn’t have to warm any more for Greenland to continue losing ice,” Box said. “It has probably passed the point where it could maintain the mass of ice that we remember.

“But that doesn’t mean that Greenland’s ice will all disappear. It’s likely that it will probably adjust to a new ‘equilibrium’ but before it reaches the equilibrium, it will shed a lot more ice.

“Greenland is deglaciating and actually has been doing so for most of the past half-century.”

Box, a researcher with Ohio State’s Byrd Polar Research Center, along with graduate students Russell Benson and David Decker, presented their findings at the annual meeting of the American Geophysical Union in San Francisco.

The research team has been monitoring satellite images of Greenland to gauge just how much ice flows from landlocked glaciers towards the ocean to form floating ice shelves. Eventually, large pieces of these ice shelves will break off into the sea, speeding up the flow of more glacial ice to add to the shelves.

Warming of the climate around Greenland is believed to have added to the increased flow of ice outward from the mainland via these huge glaciers.

Using daily images from instruments called MODIS (Moderate Resolution Imaging Spectroradiometer) aboard two of NASA’s satellites, Box and his team are able to monitor changes in 32 of the largest glaciers along Greenland’s coast.

They determined that during the summer of 2006-2007, the floating ice shelves at the seaward end of those glaciers had diminished by 24.29 square miles (62.9 square kilometers. But one year later — the summer of 2007-2008 – the ice loss had nearly tripled to nearly 71 square miles (183.8 square kilometers). Much of this additional loss is from a single large floating ice tongue called the Petermann glacier

Late this summer, the Ohio State researchers were able to watch as a massive 11-square-mile (29-square kilometer) chunk broke off from the tongue of the massive Petermann Glacier in Northern Greenland. At the time, they also noted that a massive crack further up the ice shelf suggested an even larger piece of ice would soon crack off.

Box said that some findings may have confused the public’s views of what is happening around Greenland. “For example, we know that snowfall rates have increased recently in this region,” he said, “but that hasn’t been enough to compensate for the increased melt rate of the ice that we’re seeing now.”

Researchers identify new region of the magnetosphere

llustration of the magnetosphere shows its different regions. The white arrows show the path that individual ions take as they are carried into the magnetosphere by the polar wind and then move from region to region in the magnetosphere. -  Rick Chappell
llustration of the magnetosphere shows its different regions. The white arrows show the path that individual ions take as they are carried into the magnetosphere by the polar wind and then move from region to region in the magnetosphere. – Rick Chappell

A detailed analysis of the measurements of five different satellites has revealed the existence of the warm plasma cloak, a new region of the magnetosphere, which is the invisible shield of magnetic fields and electrically charged particles that surround and protect Earth from the onslaught of the solar wind.

The study was conducted by a team of scientists headed by Charles “Rick” Chappell, research professor of physics and director of the Dyer Observatory at Vanderbilt University and published this fall in the space physics section of the Journal of Geophysical Research.
The northern and southern polar lights – aurora borealis and aurora australis – are the only parts of the magnetosphere that are visible, but it is a critical part of Earth’s space environment.

“Although it is invisible, the magnetosphere has an impact on our everyday lives,” Chappell said. “For example, solar storms agitate the magnetosphere in ways that can induce power surges in the electrical grid that trigger black outs, interfere with radio transmissions and mess up GPS signals. Charged particles in the magnetosphere can also damage the electronics in satellites and affect the temperature and motion of the upper atmosphere.”

The other regions of the magnetosphere have been known for some time. Chappell and his colleagues pieced together a “natural cycle of energization” that accelerates the low-energy ions that originate from Earth’s atmosphere up to the higher energy levels characteristic of the different regions in the magnetosphere. This brought the existence of the new region into focus.

The warm plasma cloak is a tenuous region that starts on the night side of the planet and wraps around the dayside but then gradually fades away on the afternoon side. As a result, it only reaches about three-quarters of the way around the planet. It is fed by low-energy charged particles that are lifted into space over Earth’s poles, carried behind the Earth in its magnetic tail but then jerked around 180 degrees by a kink in the magnetic fields that boosts the particles back toward Earth in a region called the plasma sheet

Chappell and his colleagues – Mathew M. Huddleston from Trevecca University, Tom Moore and Barbara Giles from the National Aeronautics and Space Administration, and Dominique Delcourt from the Centre d’etude des Environments Terrestre et Planetaires, Observatoire de Saint-Maur in France – used satellite observations to measure the properties of the ions in different locations in the magnetosphere.

An important part of their analysis was a computer program developed by Delcourt that can predict how ions move in the earth’s magnetic field. “These motions are very complicated. Ions spiral around in the magnetic field. They bounce and drift. A lot of things can happen, but Dominic developed a mathematical code that can predict where they go,” said Chappell.

When the researchers applied this computer code to the satellite observations some patterns became clear for the first time. One was the prediction of how ions could move upward from the ionosphere to form the warm plasma cloak.

“We have recognized all the other regions for a long time, but the plasma cloak was a fuzzy thing in the background which we didn’t have enough information about to make it stand out. When we got enough pieces, there it was!” said Chappell.

Climate change alters ocean chemistry

Researchers have discovered that the ocean’s chemical makeup is less stable and more greatly affected by climate change than previously believed. The researchers report in the December 12, 2008 issue of Science* that during a time of climate change 13 million years ago the chemical makeup of the oceans changed dramatically. The researchers warn that the chemical composition of the ocean today could be similarly affected by climate changes now underway – with potentially far-reaching consequences for marine ecosystems.

“As CO2 increases and weather patterns shift, the chemical composition of our rivers will change, and this will affect the oceans,” says co-author Ken Caldeira of the Carnegie Institution’s Department of Global Ecology. “This will change the amount of calcium and other elements in ocean salts.”

The research team, which included Caldeira, Elizabeth M. Griffith and Adina Paytan of the University of California, Santa Cruz, plus two other colleagues, studied core samples of deep oceanic sediment recovered from the Pacific Ocean Basin. By analyzing the calcium isotopes in grains of the mineral barite in different layers, they determined that between 13 and 8 million years ago the ocean’s calcium levels shifted dramatically. The shift corresponds to the growth of the Antarctic ice sheets during the same time interval. Because of the huge volume of water that became locked up in the ice cap, sea level also dropped.

“The climate got colder, ice sheets expanded, sea level dropped, and the intensity, type, and extent of weathering on land changed,” explains Griffith.

“This caused changes in ocean circulation and in the amount and composition of what rivers delivered to the ocean,” adds Paytan. “This in turn impacted the biology and chemistry of the ocean.”

Calcium-bearing rocks such as limestone are the largest storehouse of carbon in the Earth’s carbon cycle because they are primarily made up of calcium carbonate. “The ocean’s calcium cycle is closely linked to atmospheric carbon dioxide and the processes that control seawater’s acidity,” says Caldeira. Acidification of seawater is already a growing threat to coral reefs and other marine life.

“What we learned from this work is that the ocean system is much more sensitive to climate change than we have previously appreciated,” says Griffith. “We thought that the concentration of calcium, which is a major element in seawater, would change slowly and gradually over tens of millions of years. But what our data suggests is that there could be a more dynamic relationship between climate and ocean chemistry, which can sometimes result in rapid biogeochemical reorganization.”

“We see here how dynamic the climate-ocean system is and that the responses to change are not always what we would expect” says Paytan. “We need to keep this in mind when considering future climate and other anthropogenic changes, like ocean acidification, and their impact on the ocean and ocean resources.”