20th century one of driest in 9 centuries for northwest Africa

Ramzi Touchan of the University of Arizona's Laboratory of Tree-Ring Research takes a core from an Altas cedar, also known as Cedrus atlantica, in Morocco. -  Photo courtesy of R. Touchan, University of Arizona.
Ramzi Touchan of the University of Arizona’s Laboratory of Tree-Ring Research takes a core from an Altas cedar, also known as Cedrus atlantica, in Morocco. – Photo courtesy of R. Touchan, University of Arizona.

Droughts in the late 20th century rival some of North Africa’s major droughts of centuries past, reveals new research that peers back in time to the year 1179.

The first multi-century drought reconstruction that includes Morocco, Algeria and Tunisia shows frequent and severe droughts during the 13th and 16th centuries and the latter part of the 20th century.

An international research team figured out northwest Africa’s climate history by using the information recorded in tree rings. The oldest trees sampled contain climate data from the medieval period. One tree-ring sample from Morocco dates back to the year 883.

“Water issues in this part of the world are vital,” said lead researcher Ramzi Touchan of the University of Arizona. “This is the first regional climate reconstruction that can be used by water resource managers.”

In most of North Africa, instruments have been recording weather information for 50 years or less, too short a time to provide the long-term understanding of regional climate needed for resource planning, he said.

“One of the most important ways to understand the climate variability is to use the proxy record, and one of the most reliable proxy records is tree rings,” said Touchan, an associate research professor at UA’s Laboratory of Tree-Ring Research.

The team has developed the first systematically sampled network of tree-ring chronologies across northwest Africa, said co-author David Meko, also of UA’s Laboratory of Tree-Ring Research.

The network allowed the researchers to analyze the patterns of past droughts over the whole region, said Meko, a UA associate research professor. The width of the annual growth rings on trees in semi-arid environments is highly correlated with the amount of precipitation.

The team found the region’s 20th-century drying trend matches what climate models predict will occur as the climate warms. The research is the first to compare projections from climate models with tree-ring-based reconstructions of the region’s past climate.

The region’s trees and dead wood needed to do such research are disappearing rapidly from a combination of a massive die-off of trees, logging and population pressures, Touchan said.

“We have a chance to do what we call salvage dendrochronology,” Touchan said. These are areas where we need to get this information now or it’s going to disappear.”

Pointing to a cross-section of an old tree from Morocco, he said, “This is from 883 — and this is from a stump. If we don’t take them, they’re gone. So this is a real treasure.”

The team’s paper, “Spatiotemporal drought variability in northwestern Africa over the last nine centuries,” is now available online and will be published in a future issue of the journal Climate Dynamics. A complete list of authors and their affiliations is at the bottom of this release. The National Science Foundation funded the research.

The team sampled several different species of conifer and oak trees, because research indicates that testing several different species from the same region provides a better indicator of regional climate.

The current tree-ring chronology builds on previous work in northwest Africa by this team and by other researchers. The chronology incorporates samples from at least 20 trees from each of 39 different sites.

Persistent drought was more widespread across northwest Africa before the year 1500 than for the four centuries following, the researchers found. However, the pattern of widespread regional drought then seems to re-emerge in the late 20th century.

The spatial extent of the new regional tree-ring chronology revealed that drought in Morocco is not driven by the same kinds of oceanic and atmospheric conditions as drought in Algeria and Tunisia.

Drought in Morocco is strongly related to the north/south seesaw of air-pressure anomalies in the North Atlantic Ocean called the North Atlantic Oscillation. However, drought in Morocco is only weakly related to El Nino. By contrast, drought in Algeria and Tunisia appears more linked to a warm tropical Atlantic Ocean.

Touchan hopes to expand the new network’s geographic reach to across North Africa, including Libya and additional parts of Algeria.

In addition, he wants to extend the chronology back in time to bridge the gap to archaeological material.

Tree-ring chronologies exist for centuries deep in the past, but they are “floating,” meaning that there is no continuous record linking those chronologies to ones that reach back from the present, he said.

“If we can bridge this gap, it will be a discovery for the world,” Touchan said.

Scientists share latest Mexico earthquake data

A Joint Meeting of the Geological Society of America’s Cordilleran Section and the Pacific Section of the American Association of Petroleum Geologists, with the Western Regional Society of Petroleum Engineers, is expected to draw more than 900 geoscientists to Anaheim, California, USA, later this week.

From Mountains to Main Street, will be held 27-29 May 2010 at the Marriot Anaheim and will feature 57 technical sessions presenting new earth-science research in oral and poster formats. The meeting will be hosted locally by the Department of Geological Sciences at California State University-Fullerton.

The technical program begins at 8:40 a.m. on Thursday and ends at 4:20 p.m. on Saturday. Members of the media are invited to attend and cover scientific news.


Dr. Lucile M. Jones of the U.S. Geological Survey will present a keynote address titled, “When the Mountains Come to Main Street: Helping California Live with Natural Disasters,” on Friday, 28 May, 5:30-6:30 p.m. in the Marquis Ballroom. Dr. Jones, as head of the U.S. Geological Survey office in Pasadena, has long been the person associated with press conferences discussing recent earthquakes in southern California. Dr. Jones is now chief scientist for the Multi Hazards Demonstration Project in Southern California, integrating hazards science with economic analysis and emergency response to increase community resiliency to natural disasters. Read more about Jones at http://profile.usgs.gov/jones.

Late-Breaking Earthquake Session

In April 2010, a 7.2 magnitude earthquake occurred in Northern Baja California, Mexico. The earthquake (Sierra El Mayor-Cucapah Earthquake) occurred 30 miles south southeast of Mexicali, Mexico and caused widespread liquefaction, road ruptures, cracking of infrastructure, tilting of power line towers, and partial or total collapse of many buildings. Between 25,000 and 35,000 people were displaced.

Conveners Thomas Rockwell (San Diego State University) and John Fletcher (CICESE, Ensenada, Mexico) have assembled a late-breaking special session on Saturday, 29 May, to examine the latest data surrounding this seismic event. One new study presents one of the first uses of Light Detection And Ranging (LiDAR) for rapid scientific response following an earthquake.

View the special session schedule and abstracts:

El Mayor-Borrego Earthquake I:8:30 – 10:40 a.m.


El Mayor-Borrego Earthquake II: 1:30 – 3:10 p.m.


Marriott Anaheim Hotel: Platinum 8-9

View a complete list of meeting sessions at http://www.geosociety.org/sectdiv/cord/2010mtg/techprog.htm.

To see the session schedule and view abstracts, click http://gsa.confex.com/gsa/2010CD/finalprogram/. Search the program by session number (from list at the first link above) or by title, author, or key words.

Follow the meeting on Twitter via hashtag #Cord10.

The scientific exchange will be enhanced with pre- and post-meeting field trip options that highlight the diverse geology of southern California, including geologic features of the Mojave Desert, the pools and redwoods of Icehouse Canyon, the structural history and geochronology of Soledad and Plush Ranch Basins, volcanic unrest at Mammoth Mountain, California’s primary petroleum source rock in the Los Angeles Basin, and outcrops of the Capistrano Formation in the vicinity of San Clemente State Beach.


Find complete meeting information at http://www.geosociety.org/sectdiv/cord/2010mtg/.

Eligibility for media registration is as follows:

  • Working press representing bona fide, recognized news media with a press card, letter or business card from the publication.
  • Freelance science writers, presenting a current membership card from NASW, ISWA, regional affiliates of NASW, ISWA, CSWA, ACS, ABSW, EUSJA, or evidence of work pertaining to science published in 2009 or 2010.
  • PIOs of scientific societies, educational institutions, and government agencies.

To obtain a badge for media access, present credentials onsite to William Cox at the GSA registration desk in the Anaheim Marriott Hotel. Complimentary meeting registration covers attendance at all technical sessions and access to the exhibit hall. Journalists and PIOs must pay regular fees for paid luncheons and any short courses or field trips in which they participate. Representatives of the business side of news media, publishing houses, and for-profit corporations must register at the main registration desk and pay the appropriate fees.

Scientists collaborate to study Eyjafjallajokull lightning

For travelers in Europe, the recent eruption of Iceland’s Eyjafjallajokull [AY-uh-fyat-luh-YOE-kuutl-uh] meant a major disruption in business and travel plans. For Alaska volcano researchers, the eruption has offered a chance to learn more about the way volcanoes work.

In the wake of the eruption, the University of Alaska Fairbanks Geophysical Institute and the New Mexico Institute of Mining and Technology have teamed up again to study the lightning produced during volcanic eruptions. Past collaborations have found researchers studying the eruptions of Augustine, Pavlof and Redoubt volcanoes in Alaska, as well as Chaiten Volcano in Chile.

To study Eyjafjallajokull, researchers from New Mexico Tech have set up six instruments near the volcano as part of a lightning-mapping array. The sensor stations consist of an omnidirectional antenna hooked up to an electronics package, a data recorder, a GPS clock and other components.

The Eyjafjallajokull research is still in its infancy, but project member Steve McNutt, Alaska Volcano Observatory coordinating scientist at the Geophysical Institute, notes the research team has already observed some unusual and understudied phenomena, such as lightning that is propagated upward from the volcano’s vent toward the sky and into the ash plume. Iceland’s glacial terrain has also created some unique volcanic activity.

“Something relatively new with Iceland is that (the eruption) occurred under glacial ice,” McNutt said. “Ice is interesting because it’s the most electro-positive substance known.”

Water droplets have a negative charge, so eruption through the glacial ice creates some dynamic electrical conditions in the atmosphere.

Lightning is just one element of volcanic activity that scientists are trying to better understand. More pressing for stranded travelers, for instance, is that the scientific and aviation communities are still uncertain about the dangers posed by ash clouds, so caution tends to rule the day.

“We don’t really know what a safe level of ash in the atmosphere is,” McNutt said. “Your only safe choice is to completely avoid it.”

The collaboration between UAF and New Mexico Tech on Eyjafjallajokull offers the chance to continue gathering data for the foreseeable future. The collaboration is in the final year of a three-year National Science Foundation grant.

Scientists conclude asteroid ended the age of dinosaurs

University of Alaska Fairbanks scientist Michael Whalen is part of a team of distinguished scientists who recently compiled a wide swath of evidence striking a definitive blow in the ongoing battle over what killed the dinosaurs.

In a review published in the March 5 issue of the journal Science, the research group reaffirmed the recently challenged theory that an asteroid ended the age of the dinosaurs.

Scientists first proposed the asteroid impact theory of dinosaur mass extinction 30 years ago. The discovery of a massive crater at Chicxulub [CHICK-shuh-loob], in Mexico’s Yucatán Peninsula in 1991, strengthened that hypothesis. The Chicxulub crater is more than 120 miles wide-about the distance from Fairbanks to the Arctic Circle-and scientists believe it was created when an asteroid more than six miles wide crashed into Earth 65 million years ago. The cataclysmic impact-a million times more powerful than the largest nuclear bomb ever tested-triggered massive earthquakes, atmospheric discharge and oceanic upheaval. The ensuing mass extinction ended both the reign of the dinosaurs and the Cretaceous period, which gave way to the Paleogene period. This theory, having steadily accumulated evidence, was thought to be a near-consensus view.

Recently, however, in a series of articles, researchers posed an alternate hypothesis for the mass extinction. Some scientists claim that long-term volcanic activity at the Deccan Traps, in what is now India, caused acid rain and global cooling, gradually making life untenable for the dinosaurs and other large animals. They also suggest that the Chicxulub impact occurred some 300,000 years before the mass extinctions.

The alternate hypothesis spurred Whalen and other Chicxulub impact proponents to respond. The current Science article dispels the Deccan Traps hypothesis, arguing that the geological record favors the Chicxulub impact event theory.

“It’s as tight a case for a synchronous chain of events as we can find in the fossil record,” Whalen said.

Whalen is an associate professor at the UAF geology and geophysics department and the Geophysical Institute. He first began studying the Chicxulub site in 2002. His expertise is in carbonate rock, or limestone-a handy specialty, as limestone forms the layers above the Cretaceous-Paleogene geological boundary in the Chicxulub crater. He studied a 2001 core from the crater and compared it to seismic data gathered in 2006. His analysis offered insight on the geography of the area prior to impact, how it changed during the impact and the eventual infill of the crater by limestones deposited after the impact event.

Oregon may build nation’s first tsunami evacuation structure

Researchers at Oregon State University are using their Tsunami Wave Basin to test theoretical models of what could become the nation's first structure built specifically to withstand the force of a tsunami and serve as an emergency shelter people could run to. This is under consideration in Cannon Beach, Ore. (Photo courtesy of Oregon State University)
Researchers at Oregon State University are using their Tsunami Wave Basin to test theoretical models of what could become the nation’s first structure built specifically to withstand the force of a tsunami and serve as an emergency shelter people could run to. This is under consideration in Cannon Beach, Ore. (Photo courtesy of Oregon State University)

Residents of a small Oregon coastal community are moving closer to the creation of something that’s never before been built in the United States – a structure designed specifically to withstand a major earthquake and the force of a tsunami, and give people somewhere to run to for safety.

The earthquake is coming, on the Cascadia subduction zone off the Pacific Northwest coast. It could be massive, and almost certainly will produce a tsunami. With buildings shattered, bridges collapsed and only minutes to spare, the only way to save lives may be the concept of “vertical evacuation” to a sturdy, sufficiently tall building.

Working closely with experts from Oregon State University, the Oregon Department of Geology and Mineral Industry, and local residents, the small town of Cannon Beach wants to build a new city hall that could serve a dual purpose – public business all of its life, and a life-saving shelter on the one day that the water sweeps ashore.

A conceptual design for the 9,800-square-foot structure has been completed, a cost of $4 million estimated, public hearings held and funding support is being sought from the federal government.

But the forces of a tsunami are literally uncharted waters. Only in Japan have any structures designed to survive a tsunami been built, and none actually put to the test. So among other support efforts, engineers at OSU are now testing a model of the proposed structure in their Tsunami Wave Basin, the most sophisticated facility of its type in the world.

“We’re heading in the right direction, but this is new territory,” said Dan Cox, a professor of coastal and ocean engineering at OSU. “There’s a lot we still need to learn about the impact of forces from waves, cars, collapsed buildings and other debris, and just how strong a building must be to resist that. But our tests should help add a higher degree of confidence in this design.”

It’s known that a building that is strong enough, with a deep foundation and perhaps protective seawalls, can withstand these forces. But cost is also an issue. With current plans it’s estimated the Cannon Beach structure will cost twice as much as one that otherwise might be built, so an engineering challenge is to keep costs down while ensuring the structure will do its job.

These issues are being faced not just in this small community, but in other low-lying, coastal cities from northern California to British Columbia, all of which are exposed to earthquakes on the Cascadia subduction zone.

In the massive earthquake and tsunami in Sumatra and the Indian Ocean in 2004, more than 200,000 people died, most of them not from the earthquake but rather the resulting tsunami. That event was quite similar geologically to what the Pacific Northwest faces. Subduction zone ruptures cause the most powerful earthquakes in the world. And research – including major studies at OSU – have now tracked repeated earthquakes on the Cascadia subduction zone, the last one on a winter day in 1700. It’s possible the next event could happen at any time, and OSU experts have estimated a 37 percent possibility of a rupture within the next 50 years.

“Every community from Cape Mendocino in California to Vancouver Island in Canada is vulnerable to some extent to the Cascadia subduction zone earthquake and tsunamis,” said Patrick Corcoran, an OSU Sea Grant Extension hazards outreach specialist. “This is arguably the greatest recurring natural hazard in the lower 48 states. Our cities are not engineered to deal with it and our residents are not prepared for it. We need evacuation routes, assembly sites, public education and outreach. And in some places, we need vertical evacuation structures.

“The only way to potentially save thousands of lives is through more education and better engineering.”

Part of the problem, experts say, is that only in the past 25 years did a scientific understanding develop of the profound risks posed by this subduction zone. Thirty years ago it wasn’t even clear that Cascadia caused major earthquakes. It’s now believed capable of an earthquake of magnitude nine or larger, similar to that of the deadly Indian Ocean event in 2004.

As cities and smaller towns wrestle with what to do, officials in Cannon Beach want to act.

“In all but the most catastrophic scenarios, it’s been estimated that the water level from an incoming tsunami at the site we propose to build the new city hall could be up to 15 feet,” said Jay Raskin, a local architect and one of the community leaders working to create the new structure. “We think this building could shelter at least 1,500 people. It will cost more, but so far there has been a pretty positive public reaction to the idea.”

If funded and constructed, Raskin said, this structure could serve as a both a physical and inspirational model for many other cities potentially affected by a tsunami. The project has already gained some international attention, he said. And a building that could stand slightly above the incoming water and withstand its force is not the only approach to vertical evacuation – in Washington state’s Long Beach peninsula where more land is available, officials are considered building a series of berms, essentially artificial hills that would be high enough to get above the water. If structures are built, they could be designed to serve various purposes, such as ocean viewing platforms or picnic areas.

Harry Yeh, holder of the Miles Lowell and Margaret Watt Edwards Distinguished Chair in Engineering at OSU, is also helping Cannon Beach do a tsunami evacuation study, which will help outline the scope of the problem. It assumes, for instance, that a major earthquake will collapse the bridge over Ecola Creek, cutting off part of the town’s population from the rest. A pedestrian bridge over the creek that might at least survive the earthquake, if not the tsunami, is one thing that could be considered, Raskin said.

Cannon Beach has about 1,700 residents, and thousands more visitors are possible during some peak tourist days. But the problems it faces are similar to dozens of coastal communities in California, Oregon and Washington.

“We probably would have built these communities differently if we knew 50 years ago what we know today,” Corcoran said. “But it’s also worth noting this isn’t just their problem. This coastline is very beautiful and people come from all over the world to see it, many thousands of them on nice days. This earthquake is coming. So we all have a stake in doing what we can to prepare for it.”

Odds are about 1-in-3 that a mega-earthquake will hit the Northwest in the next 50 years

The major earthquakes that devastated Chile earlier this year and which triggered the catastrophic Indonesian tsunami of 2004 are more than just a distinct possibility to strike the Pacific Northwest coast of the United States, scientists say.

There is more than a one-in-three chance that it will happen within the next 50 years.

New analysis by Oregon State University marine geologist Chris Goldfinger and his colleagues have provided fresh insights into the Northwest’s turbulent seismic history – where magnitude 8.2 (or higher) earthquakes have occurred 41 times during the past 10,000 years. Those earthquakes were thought to generally occur every 500 years, but as scientists delve more deeply into the offshore sediments and other evidence, they have discovered a great deal more complexity to the Cascadia Subduction Zone.

“What we’ve found is that Cascadia isn’t one big subduction zone when it comes to major earthquakes,” Goldfinger said. “It actually has several segments – at least four – and the earthquake activity is different depending on where a quake originates. The largest earthquakes occur in the north and usually rupture the entire fault. These are quakes of about magnitude-9 and they are just huge – but they don’t happen as frequently.

“At the southern end of the fault, the earthquakes tend to be a bit smaller, but more frequent,” he added. “These are still magnitude-8 or greater events, which is similar to what took place in Chile, so the potential for damage is quite real.”

Based on historical averages, Goldfinger says the southern end of the fault – from about Newport, Ore., to northern California – has a 37 percent chance of producing a major earthquake in the next 50 years. The odds that a mega-quake will hit the northern segment, from Seaside, Ore., to Vancouver Island in British Columbia, are more like 10 to 15 percent.

“Perhaps more striking than the probability numbers is that we can now say that we have already gone longer without an earthquake than 75 percent of the known times between earthquakes in the last 10,000 years,” Goldfinger said. “And 50 years from now, that number will rise to 85 percent.”

Understanding the Cascadia Subduction Zone history is further complicated by the possibility that major earthquakes in the northern segment have occurred in “clusters.” A thousand years may go by without a major event, and then an earthquake would occur every 250 years or so.

“We’re just starting to understand the whole idea of clusters and there isn’t consensus on whether we are in one or not,” Goldfinger said, “but that possibility does exist, which further suggests that we may experience a major earthquake sooner than later.”

The last major earthquake to hit the Cascadia Subduction Zone was in January of 1700, and scientists are aware of the impact because of written records from Japan documenting the damage caused by the ensuing 30-foot tsunami. Their knowledge about what happened in Oregon and Washington is more speculative, but the consensus – gleaned from studies of coastal estuaries, land formations, and river channels – is that the physical alteration to the coast was stunning.

Goldfinger, who is a professor in OSU’s College of Oceanic and Atmospheric Sciences, is one of the leading experts on the Cascadia Subduction Zone and his comparative studies have taken him to the Indian Ocean and, most recently to Chile. In 2007, he led the first American research ship into Sumatra waters in nearly 30 years to study similarities between the Indian Ocean subduction zone and that off the Northwest coast.

When a major offshore earthquake occurs, Goldfinger says, the disturbance causes mud and sand to begin streaming down the continental margins and into the undersea canyons. Coarse sediments called turbidites run out onto the abyssal plain; these sediments stand out distinctly from the fine particulate matter that accumulates on a regular basis between major tectonic events.

By dating the fine particles through carbon-14 analysis and other methods, Goldfinger and colleagues can estimate with a great deal of accuracy when major earthquakes have occurred.

Goldfinger has used the technique to recreate the seismic history of the Cascadia Subduction Zone over the past 10,000 years. Going back further than 10,000 years has been difficult because the sea level used to be lower and West Coast rivers emptied directly into offshore canyons, he pointed out. Because of that, it was difficult to distinguish between storms debris and earthquake turbidites.

The OSU professor is convinced that the Pacific Northwest is at risk for an earthquake that could meet – or exceed – the power of seismic events that took place in Chile, as well as Haiti. If a magnitude-9 earthquake does strike Cascadia, he says, the ground could shake for several minutes. Highways could be torn to pieces, bridges may collapse, and buildings would be damaged or even crumble. If the epicenter is just offshore, coastal residents could have as little as 15 minutes of warning before a tsunami could strike.

That immediacy is why engineering and coastal communities are exploring different ways of evacuating low-lying areas, including the construction of high-rise, tsunami-resistant facilities.

“It is not a question of if a major earthquake will strike,” Goldfinger said, “it is a matter of when. And the ‘when’ is looking like it may not be that far in the future.”

Greenland rapidly rising as ice melt continues

This is a satellite image of Western Greenland, acquired by NASA's MODIS satellite. The  narrow grey band  in the center of the image is melting ice,  between the rocky coast to the left (west) and  thicker, non-melting, higher altitude ice to the right (east). Small lakes form in this region during the summer.  Arrow points to darker grey zone of rapidly thinning ice near the outlet of Jacobshavn glacier, which also loses mass due to iceberg calving. -  Courtesy of NASA
This is a satellite image of Western Greenland, acquired by NASA’s MODIS satellite. The narrow grey band in the center of the image is melting ice, between the rocky coast to the left (west) and thicker, non-melting, higher altitude ice to the right (east). Small lakes form in this region during the summer. Arrow points to darker grey zone of rapidly thinning ice near the outlet of Jacobshavn glacier, which also loses mass due to iceberg calving. – Courtesy of NASA

Greenland is situated in the Atlantic Ocean to the northeast of Canada. It has stunning fjords on its rocky coast formed by moving glaciers, and a dense icecap up to 2 km thick that covers much of the island–pressing down the land beneath and lowering its elevation. Now, scientists at the University of Miami say Greenland’s ice is melting so quickly that the land underneath is rising at an accelerated pace.

According to the study, some coastal areas are going up by nearly one inch per year and if current trends continue, that number could accelerate to as much as two inches per year by 2025, explains Tim Dixon, professor of geophysics at the University of Miami Rosenstiel School of Marine and Atmospheric Science (RSMAS) and principal investigator of the study.

“It’s been known for several years that climate change is contributing to the melting of Greenland’s ice sheet,” Dixon says. “What’s surprising, and a bit worrisome, is that the ice is melting so fast that we can actually see the land uplift in response,” he says. “Even more surprising, the rise seems to be accelerating, implying that melting is accelerating.”

Dixon and his collaborators share their findings in a new study titled “Accelerating uplift in the North Atlantic region as an indicator of ice loss,” The paper is now available as an advanced online publication, by Nature Geoscience. The idea behind the study is that if Greenland is losing its ice cover, the resulting loss of weight causes the rocky surface beneath to rise. The same process is affecting the islands of Iceland and Svalbard, which also have ice caps, explains Shimon Wdowinski, research associate professor in the University of Miami RSMAS, and co-author of the study.

“During ice ages and in times of ice accumulation, the ice suppresses the land,” Wdowinski says. “When the ice melts, the land rebounds upwards,” he says. “Our study is consistent with a number of global warming indicators, confirming that ice melt and sea level rise are real and becoming significant.”

Using specialized global positioning system (GPS) receivers stationed on the rocky shores of Greenland, the scientists looked at data from 1995 onward. The raw GPS data were analyzed for high accuracy position information, as well as the vertical velocity and acceleration of each GPS site.

The measurements are restricted to places where rock is exposed, limiting the study to coastal areas. However, previous data indicate that ice in Greenland’s interior is in approximate balance: yearly losses from ice melting and flowing toward the coast are balanced by new snow accumulation, which gradually turns to ice. Most ice loss occurs at the warmer coast, by melting and iceberg calving and where the GPS data are most sensitive to changes. In western Greenland, the uplift seems to have started in the late 1990’s.

Melting of Greenland’s ice contributes to global sea level rise. If the acceleration of uplift and the implied acceleration of melting continue, Greenland could soon become the largest contributor to global sea level rise, explains Yan Jiang, Ph.D. candidate at the University of Miami RSMAS and co-author of the study.

“Greenland’s ice melt is very important because it has a big impact on global sea level rise,” Jiang says. “We hope that our work reaches the general public and that this information is considered by policy makers.”

This work was supported by the National Science Foundation and NASA. The team plans to continue its studies, looking at additional GPS stations in sensitive coastal areas, where ice loss is believed to be highest.

Geologists show unprecedented warming in Lake Tanganyika

Jessica Tierney is a geologist at Brown University. -  Brown University
Jessica Tierney is a geologist at Brown University. – Brown University

Lake Tanganyika, the second oldest and the second-deepest lake in the world, could be in for some rough waters.

Geologists led by Brown University have determined the east African rift lake has experienced unprecedented warming during the last century, and its surface waters are the warmest on record. That finding is important, the scientists write in the journal Nature Geoscience, because the warm surface waters likely will affect fish stocks upon which millions of people in the region depend.

The team took core samples from the lakebed that laid out a 1,500-year history of the lake’s surface temperature. The data showed the lake’s surface temperature, 26 degrees Celsius (78.8°F), last measured in 2003, is the warmest the lake has been for a millennium and a half. The team also documented that Lake Tanganyika experienced its biggest temperature change in the 20th century, which has affected its unique ecosystem that relies upon the natural conveyance of nutrients from the depths to jumpstart the food chain upon which the fish survive.

“Our data show a consistent relationship between lake surface temperature and productivity (such as fish stocks),” said Jessica Tierney, a Brown graduate student who this spring earned her Ph.D. and is the paper’s lead author. “As the lake gets warmer, we expect productivity to decline, and we expect that it will affect the [fishing] industry.”

The research grew out of two coring expeditions sponsored by the Nyanza Project in 2001 and 2004. Cores were taken by Andrew Cohen, professor of geological sciences at the University of Arizona and director of the Nyanza project, and James Russell, professor of geological sciences at Brown, who is also Tierney’s adviser.

Lake Tanganyika is bordered by Burundi, the Democratic Republic of Congo, Tanzania, and Zambia – four of the poorest countries in the world, according to the United Nations Human Development Index. An estimated 10 million people live near the lake, and they depend upon it for drinking water and for food. Fishing is a crucial component for the region’s diet and livelihood: Up to 200,000 tons of sardines and four other fish species are harvested annually from Lake Tanganyika, a haul that makes up a significant portion of local residents’ diets, according to a 2001 report by the Lake Tanganyika Biodiversity Project.

Lake Tanganyika, one of the richest freshwater ecosystems in the world, is divided into two general levels. Most of the animal species live in the upper 100 meters, including the valuable sardines. Below that, the lake holds less and less oxygen, and at certain depths, it is anoxic, meaning it has no oxygen at all. What this all means is the lake is highly stratified and depends on wind to churn the waters and send nutrients from the depths toward the surface as food for algae, which supports the entire food web of the lake. But as Lake Tanganyika warms, the mixing of waters is lessened, the scientists find, meaning less nutrients are funneled from the depths toward the surface. Worse, more warming at the surface magnifies the difference in density between the two levels; even more wind is needed to churn the waters enough to ferry the nutrients toward the fish-dwelling upper layer.

The researchers’ data show that during the last 1,500 years, intervals of prolonged warming and cooling are linked with low and high algal productivity, respectively, indicating a clear link between past temperature changes and biological productivity in the lake.

“The people throughout southcentral Africa depend on the fish from Lake Tanganyika as a crucial source of protein,” Cohen noted. “This resource is likely threatened by the lake’s unprecedented warming since the late 19th century and the associated loss of lake productivity.”

Climate change models show a general warming in the region, which, if accurate, would cause even greater warming of the Lake Tanganyika’s surface waters and more stratification in the lake as a whole. “So, as you move forward, you can imagine that density gradient increasing,” Russell said.

Some researchers have posited that the declining fish stocks in Lake Tanganyika can be attributed mainly to overfishing, and Tierney and Russell say that may be a reason. But they note that the warming in the lake, and the lessened mixing of critical nutrients is exacerbating the stocks’ decline, if not causing it in the first place. “It’s almost impossible for it not to,” Russell said.

Grad student to study unique soil around Yellowstone hot springs

A Montana State University graduate student has received a fellowship to study soil crusts unlike any he has ever seen.

Located around some of the hot springs in Yellowstone National Park, the soil is very fine, soft and has a unique rippled texture that reminds him of a brain, said James Meadow, recipient of the Boyd Evison Graduate Fellowship. It houses microorganisms, but mostly consists of the glassy dead bodies of diatoms. Diatoms are microscopic algae that turn light into energy. Their cell walls are made of silica.

“The diatoms are what makes this soil crust so unique,” Meadow said. “Diatom deposits are generally only found in lake and marine sediments. … It is very unique to find these deposits growing on the soil surface.”

He noticed the unusual crust while sampling plants near alkaline hot pools in the Imperial Meadow of the Lower Geyser Basin, Meadow said. Working on his Ph.D. in ecology and environmental sciences, Meadow said his primary research deals with fungi that live symbiotically with plant roots. Symbiosis occurs in all soil systems, but his Ph.D. research focuses on fungi that thrive in harsh thermal environments.

Cathy Zabinski, his adviser in MSU’s Department of Land Resources and Environmental Sciences, said ,”If we can understand how plant/microbe interactions enable plants to grow in this extreme environment, we can also apply those same principles to other extreme environments, such as remediation sites after mining activities. We are also using this work to understand how plants might respond to warming soil temperatures in the future.”

Grand Teton National Park and the Grand Teton Association selected Meadow out of 19 applicants for the 2010 fellowship that honors the late Boyd Evison. Evison worked 42 years with the National Park Service and then became executive director for the Grand Teton Association, which is dedicated to aiding interpretive, educational and research programs for Grand Teton National Park. The fellowship program — which will give Meadow approximately $10,000 over two years — encourages scientific and conservation-related research in Grand Teton and throughout the Greater Yellowstone. It supports research leading to a master’s or doctoral degree in the biosciences, geosciences or social sciences.

The fellowship allows recipients to develop their own ideas, independent of the projects their advisers have funded, Zabinski said.

“From a graduate training perspective, there is no better way to prepare students for the academic job market,” Zabinski said.

Meadow said he will use his fellowship to study the composition, diversity and ecological environmental of the soil he observed in Yellowstone. The soil changes color and texture with the season. A product of thermal vents, it is loaded with chemicals, especially silica.

A major benefit of the fellowship is that it will allow him to conduct molecular analysis, Meadow added. Instead of identifying organisms under a microscope, which could take years, he can crush small samples of the soil, pull as much DNA as possible and run tests to identify the organisms that live in the soil and, to some extent, tell what they are doing.

“It’s pretty common to find new organisms in these environments,” Meadow said. “What I have seen so far is, it seems to be a combination of common crust organisms, along with those only found in thermal environments.

Soil crusts — generally called biological soil crusts — are composed mostly of bacteria (primarily cyanobacteria), fungi, lichens and mosses, Meadow said. They also incorporate the top few millimeters of soil. They dominate in arid soils where plants are limited and open patches of soil are exposed to full sunlight.

Scientists have conducted extensive studies of the crust environments in Canyonlands National Park and Arches National Park, both in Utah, Meadow said. But he found nothing to indicate that anyone had researched thermal crusts like he noticed in Yellowstone.

His findings — besides contributing to general scientific knowledge — will be shared with the Grand Teton Association, park visitors and others, Meadow said. He will work with park staff to create interpretative materials that will explain the diversity of life forms that live only in thermal ecosystems, specifically the soil.

His research might also contribute to environmental restoration, Meadow said. Meadow worked on ecological restoration projects at mines and other industrial sites throughout the West before coming to MSU.

“Doing that, it became obvious to me that a lot of the time restoration kind of fails because we don’t really understand how organisms live in really harsh environments in natural systems,” Meadow said. “Thermal soil biology gives me a chance to see how organisms cope with really, really tough environments.”

Zabinski said the area is “absolutely fascinating.”

“You find really poorly developed soils, low nutrient levels for plant growth, soil temperatures that are at the extreme of what plant tissues can tolerate, and a set of plants, some of which only grow on hot soils and others which are widely distributed and can also tolerate the heat,” she said.

Scientists make statements on concentration of ash particles after volcanic eruption

This is a simulation of the volcanic ash concentration between a height of approx. 2,000 and 7,000 meters on April 17, 2010 (right). On the left, by way of comparison, is the spread forecast by the VAAC (red line). -  GKSS Research Centre Geesthacht
This is a simulation of the volcanic ash concentration between a height of approx. 2,000 and 7,000 meters on April 17, 2010 (right). On the left, by way of comparison, is the spread forecast by the VAAC (red line). – GKSS Research Centre Geesthacht

Some German airlines leveled their criticism against the forecasts of the Volcanic Ash Advisory Centre (VAAC) in London on the spread of the ash cloud over Europe, as these forecasts did not provide any precise information on the ash concentration in the atmosphere. Scientists at the GKSS Research Centre Geesthacht managed to reconstruct the spread process and make statements on the concentration of ash particles.

As a result of the eruption of the Icelandic volcano Eyjafjallajökul, from mid-April 2010 to the end of the same month, an ash cloud spread across Europe which resulted in severe disruptions to air travel. As the ash can damage jet engines, aircraft were not allowed to cross the airspace for a long time. Airports remained closed. Some German airlines doubted the necessity of restricting flight movements.

The VAAC monitors the movement of volcanic ash clouds for the international aviation and supplies the German weather services with necessary data, with which the spread of the cloud was assessed and the information transmitted to the traffic ministry. “These data, however, do not contain any information on the actual concentration of the ash particles,” explains Volker Matthias, scientist at the GKSS Research Centre.

For this reason, the airlines doubted that the many flight cancellations were actually necessary on this scale. “In order to be able to make reliable statements on the concentration of ash particles, we have compared calculated values of the light attenuation caused by the ash particles with measured values,” adds the employee from the Institute of Coastal Research.

Reconstruction of the spread of the ash cloud

GKSS employees used mathematical models to reconstruct the spread process of the cloud. The findings of the scientists confirmed the spread of the ash cloud, as it was forecast by the VAAC, in addition, they also allowed important evaluations of the concentration of ash particles at various heights and the probable strength of the ash eruption.

It became clear that the ash spread was very inhomogeneous in terms of geography, e.g. on 19 April ash concentrations of some 50 micrograms per cubic meter were calculated above Southern Germany, while the air was relatively clean over Northern Germany.

The simulations were compared with the preliminary results of a measurement flight of the German Aerospace Centre of 19 April between 3.00 pm and 6.00 pm UTC, which were made publicly accessible on the Internet. Here, the spatial pattern of the ash cloud, calculated with the models as well as the modeled aerosol concentration, matched within the measurement error.

Statements on the concentration of ash particles

In addition, claims on the concentration of the ash particles were hedged by a comparison of the simulated optical thickness or light attenuation of the ash cloud and all other atmospheric particles with measured data. This could be done because the simulations included all particles, also those which are found close to ground. The measurement data were supplied by the ground-measurement stations of the Aerosol Robotic Network (AERONET) in Hamburg, Helgoland, Leipzig, Cabauw (Netherlands), Lille (France) and Chilbolton (UK).

Subsequently, these were compared with several model calculations, which differed as regards the assumed emission strength of the volcano. The probable scenario appeared to be that the volcano initially emitted, among other large particles that fall down to ground within a few hundred kilometres distance, about four tonnes per second of small ash particles, which can be transported over great distances. However, the emissions then became smaller until 21 April.

The researchers interpret these findings as a confirmation that only a combination of measurements and model calculations allow reliable statements, both on the geographical and temporal dynamics as well as on the concentrations of volcanic ash.