Why Is Arctic Sea Ice Melting Faster Than Predicted? NOAA Probing Arctic Pollution

Pollutants from industry, transportation, and biomass burning form an “Arctic Haze” over much of the polar region in winter and spring. (Credit: NOAA)

NOAA scientists are now flying through springtime Arctic pollution to find out why the region is warming – and summertime sea ice is melting – faster than predicted. Some 35 NOAA researchers are gathering with government and university colleagues in Fairbanks, Alaska, to conduct the study through April 23.

“The Arctic is changing before our eyes,” said A.R. Ravishankara, director of the chemistry division at NOAA’s Earth System Research Laboratory in Boulder, Colo. “Capturing in detail the processes behind this large and surprisingly rapid transformation is a unique opportunity for understanding climate changes occurring elsewhere.”

Observations from instruments on the ground, balloons, and satellites show the Arctic is warming faster than the rest of the globe. Summer sea-ice extent has decreased by nearly 40 percent compared to the 1979-2000 average, and the ice is thinning.

Industry, transportation, and biomass burning in North America, Europe, and Asia are emitting trace gases and tiny airborne particles that are polluting the polar region, forming an “Arctic Haze” every winter and spring. Scientists suspect these pollutants are speeding up the polar melt.

Called ARCPAC (Aerosol, Radiation, and Cloud Processes affecting Arctic Climate Change), the project is a NOAA contribution to International Polar Year 2008. The experiment will be coordinated with the agency’s long-term climate monitoring station at Barrow, Alaska, and with simultaneous projects conducted by NASA and the Department of Energy.

“This is our first airborne deployment of a powerful new suite of instruments in the Arctic,” said ARCPAC lead scientist Dan Murphy, also of NOAA’s Earth System Research Laboratory. “When we analyze all the data, we’ll be able to piece together the equivalent of a ‘high-def’ movie of the atmosphere as springtime sunlight warms the region and sparks a chain of chemical reactions.”

Scientists aboard the NOAA WP-3D research aircraft will use nearly 30 airborne sensors to answer questions about airborne particles, altered clouds, low-altitude ozone, and soot deposited on snow. All are produced or affected by human activities and may be playing key roles in the rapid warming.

In a related study, also taking place this month, the NOAA-led International Chemistry Experiment in the Arctic Lower Troposphere (ICEALOT) will gather shipboard measurements of atmospheric fine particles and trace gases in the air above the North Greenland and Barents seas, which are closer to sources than the ARCPAC study area. NOAA scientists are eager to compare the pollution north of Alaska with the more recent emissions near Europe.

Grand Canyon May Be As Old As Dinosaurs, According To New Geologic Dating Study

The Grand Canyon
The Grand Canyon

New geological evidence indicates the Grand Canyon may be so old that dinosaurs once lumbered along its rim, according to a study by researchers from the University of Colorado at Boulder and the California Institute of Technology.

The team used a technique known as radiometric dating to show the Grand Canyon may have formed more than 55 million years ago, pushing back its assumed origins by 40 million to 50 million years. The researchers gathered evidence from rocks in the canyon and on surrounding plateaus that were deposited near sea level several hundred million years ago before the region uplifted and eroded to form the canyon.

A paper on the subject will be published in the May issue of the Geological Society of America Bulletin. CU-Boulder geological sciences Assistant Professor Rebecca Flowers, lead author and a former Caltech postdoctoral researcher, collaborated with Caltech geology Professor Brian Wernicke and Caltech geochemistry Professor Kenneth Farley on the study, which was conducted while Flowers was at Caltech.

“As rocks moved to the surface in the Grand Canyon region, they cooled off,” said Flowers. “The cooling history of the rocks allowed us to reconstruct the ancient topography, telling us the Grand Canyon has an older prehistory than many had thought.”

The team believes an ancestral Grand Canyon developed in its eastern section about 55 million years ago, later linking with other segments that had evolved separately. “It’s a complicated picture because different segments of the canyon appear to have evolved at different times and subsequently were integrated,” Flowers said.

The ancient sandstone in the canyon walls contains grains of a phosphate mineral known as apatite — hosting trace amounts of the radioactive elements uranium and thorium — which expel helium atoms as they decay, she said. An abundance of the three elements, paired with temperature information from Earth’s interior, provided the team a clock of sorts to calculate when the apatite grains were embedded in rock a mile deep — the approximate depth of the canyon today — and when they cooled as they neared Earth’s surface as a result of erosion.

Apatite samples from the bottom of the Upper Granite Gorge region of the Grand Canyon yield similar dates as samples collected on the nearby plateau, said Caltech’s Wernicke. “Because both canyon and plateau samples resided at nearly the same depth beneath the Earth’s surface 55 million years ago, a canyon of about the same dimensions of today may have existed at least that far back, and possibly as far back as the time of dinosaurs at the end of the Cretaceous period 65 million years ago.”

One of the most surprising results from the study is the evidence showing the adjacent plateaus around the Grand Canyon may have eroded away as swiftly as the Grand Canyon itself, each dropping a mile or more, said Flowers. Small streams on the plateaus appear to have been just as effective at stripping away rock as the ancient Colorado River was at carving the massive canyon.

“If you stand on the rim of the Grand Canyon today, the bottom of the ancestral canyon would have sat over your head, incised into rocks that have since been eroded away,” said Flowers. The ancestral Colorado River was likely running in the opposite direction millions of years ago, she said.

When the canyon was formed, it probably looked like a much deeper version of present-day Zion Canyon, which cuts through strata of the Mesozoic era dating from about 250 million to 65 million years ago, Wernicke said. From 28 million to 15 million years ago, a pulse of erosion deepened the already-formed canyon and also scoured surrounding plateaus, stripping off the Mesozoic strata to reveal the Paleozoic rocks visible today, he said.

The prevailing belief is that the canyon was incised by an ancient river about six million years ago as the surrounding plateau began rising from sea level to the current elevation of about 7,000 feet. The new scenario described in the GSA Bulletin by Flowers and her colleagues is consistent with recent evidence by other geologists using radiometric dating techniques indicating the Grand Canyon is significantly older than scientists had long believed.

The National Science Foundation and Caltech funded the study.

Better Dams, Levees, Embankments: Soil Type And Compaction Factors Can Make Soil 1,000 Times More Resistant To Erosion

ARS hydraulic engineer Gregory J. Hanson, inventor of the JET test apparatus, uses a field version of the new laboratory device to measure erodibility. (Credit: Image courtesy G. Hanson)
ARS hydraulic engineer Gregory J. Hanson, inventor of the JET test apparatus, uses a field version of the new laboratory device to measure erodibility. (Credit: Image courtesy G. Hanson)

The safety of earthen embankments, including levees and dams, depends in large part on how resistant they are to erosion. That resistance can hinge on the soil materials used in their construction.

Hydraulic engineers Gregory J. Hanson and Sherry L. Hunt work at the Agricultural Research Service (ARS) Hydraulic Engineering Research Unit in Stillwater, Okla. They have refined methods for estimating the erodibility of large embankment structures with a lab-scale version of the Jet Erosion Test (JET).

Hanson developed JET to evaluate the condition of streams and dam embankments. In the field, JET applies stresses to soil beds with a water jet that can be pumped at various flow rates.

The team studied the roles of compaction effort-the mechanical force needed to increase soil density-and water content in soil erosion. They measured compaction effort using standard engineering tests, which involve dropping a hammer onto soil samples from a specific distance for a specified number of times. As part of their evaluation of compaction effort, they also varied the soil water content, which affects soil plasticity, in their samples.

The engineers observed that the erodibility of their lab samples varied significantly between the two soil types they tested, which were a silty sand and a silty clay. Both soil types also exhibited a large range of erosion, depending on compaction effort and water content.

For instance, lab soil samples that were compacted while containing optimum levels of water showed a significantly stronger resistance to erosion. Higher compaction efforts also increased erosion resistance, and soil texture and plasticity influenced erosion resistance as much, or sometimes even more, than compaction factors. The team compared these results with large-scale field controls and found that their lab-scale JET tests accurately assessed soil erodibility in samples as small as 10 centimeters in diameter.

Overall, these results indicate that soil type and compaction factors can be used to make soil at least 1,000 times more resistant to erosion. These findings will help engineers factor in soil type and other variables to predict embankment failure rates when designing flood control structures.

Grant Enables Extensive Mapping of Idaho Geology

Thanks to a generous grant, researchers at the Idaho Geological Survey at the University of Idaho will be able to map the region, including earthquake-prone areas. Idaho ranks fifth in the nation for risk caused by seismic shaking.

The $230,600 grant from the U.S. Geological Survey will enable IGS to map parts of the state under the USGS STATEMAP program, which works to establish the geologic framework of areas that are vital to the welfare of individual states. The award was the largest granted among the 44 states that competed for $6.5 million in available funds.

“New geologic maps are important for interpreting landslides, ground-water, and mineral deposits like gold and molybdenum,” said Kurt Othberg, research geologist with the Idaho Geological Survey. “Geologic maps help Idaho’s citizens to conduct activities on the land safely and responsibly.”

Research this year involves an intensive field study covering 800 square miles in project areas near Bonners Ferry, Slate Creek, Fairfield, Salmon and Idaho Falls. The mapping also is important in other applications, such as water resources, natural hazards, soil conservation, land development, and industrial and metallic minerals.

Geologic maps offer a three-dimensional view of the rock, sediment and soil on the earth’s surface, and describe structure, age, and other features at and below the surface.

The federal National Cooperative Geologic Mapping Act provides support through STATEMAP to fund annual competitive grants, which are open to state geological surveys. Since 1993, IGS has received more than $2.4 million in STATEMAP funding to support its work.

The mapping team consists of nine IGS staff members and six university scientists. The finished maps will be digitized for cartographic production in a statewide GIS database. Finished products may be viewed on the IGS’s Web site at http://www.idahogeology.org” TARGET=”_External1″>www.idahogeology.org, or purchased at the IGS public inquiry and sales office in Morrill Hall, 820 Idaho Ave., on the University of Idaho campus.

Seismologist’s Project Uses Public’s Laptops to Monitor and Predict Earthquakes

Network of computers senses earthquake and sends warning, potentially saving lives

A simple idea for monitoring earthquakes that Elizabeth Cochran, a seismologist at UC Riverside, came up with in 2006 is being realized today, and has the potential to save lives in case an earthquake strikes.

The idea involves inviting the public to help monitor earthquakes by simply using their laptop computers at home. In doing so, the laptops join a network of computers designed to take a dense set of measurements that can help capture an earthquake.

Anyone with a personal computer will be able to participate in the experiment once software linking such computers to the project is publicly released, tentatively this summer. The free software, being developed by Cochran and colleagues Jesse Lawrence of Stanford University and Carl Christensen, a software architect and consultant, will be available at the Website BOINC.

Because the project makes use of inexpensive motion sensors, called accelerometers, which are already in place as safety devices in most new laptops, participants incur no significant costs related to the project.

Called “Quake-Catcher Network,” the project involves distributed computing, a method in which different parts of a computer program run simultaneously on two or more computers that are in communication with a central server over a network.

“We’re turning the laptops’ accelerometers into earthquake monitors,” said Cochran, an assistant professor of seismology in the Department of Earth Sciences. “With a dense grid of detectors in place, an early warning can be sent through the Internet to neighboring cities should an earthquake strike, giving people up to 10-20 seconds to prepare themselves before the seismic waves reach them.”

Already, about 300 people spread around the world are taking part in the Quake-Catcher Network, with roughly a third of the participants in the United States.

“The idea is to fill in the spaces – or holes – in the seismic network currently being used to report earthquakes,” Cochran said. “With the public’s participation in Quake-Catcher Network, however, we can have a lot more ‘stations’ recording earthquakes, allowing for a better early warning system. At present in California, no such early warning system for earthquakes exists.”

Currently, approximately 350 stations monitor earthquakes in Southern California using underground sensors. They do so, however, not in real time.

“There is a delay of 10-15 seconds from when the sensors record an earthquake to when the data is processed at either Caltech in Southern California or UC Berkeley in Northern California,” Cochran explained. “Quake-Catcher Network would process data in real time, as it comes in. And the network can stretch out to any region of the world. Besides being inexpensive, it makes an extremely small demand on CPU resources.”

According to Cochran, a person’s laptop needs to remain inactive for at least three minutes before the system starts up. “This is to get rid of noise in the data and to ensure that any movement the laptop’s accelerometer is detecting is indeed out of the ordinary,” she said.

Currently, only Apple computers can participate in the project, but Cochran and her colleagues are working on including other computers in Quake-Catcher Network.

“We also are working on developing an accelerometer which can be plugged into a desktop like a USB flash drive,” she said. “That way, we’d have less interference from typing on the keyboard. It also would allow for a more robust and reliable system, with computers running the software all of the time.”

Cochran said she plans to make all the data gathered by the sensors freely available to researchers and the public.

“This data can be used to study how a seismic wave propagates in the ground,” she said. “How fast a wave travels can give us useful information, such as more details on seismic hazard as well as the structure of the Earth. The denser our network, the clearer will be the picture of what is happening at each step in time. A series of such pictures could be used to develop a movie showing the wave’s propagation, which could give us extremely useful information about seismic waves.”

Next, Cochran and her colleagues will further test their software program before its release on BOINC; currently, the program is available on very limited release.

Cochran also plans to involve K-12 schools through education and outreach. “We think this would be an excellent project for students to take an interest in,” she said, “so we’re hoping we’ll see more of their participation.”

Study heats up ‘snowball Earth’ debate

Research by University Professor Richard Peltier of physics reveals that the Earth’s surface 700 million years ago may have been warmer than previously thought.

Peltier developed a climate model that casts doubt on the popular “snowball Earth” hypothesis, a theory that posits the Earth was completely covered in ice and photosynthesis ceased during the late Neoproterozoic period.

The U of T physicist has found that the Neoproterozoic ocean’s natural carbon cycle produced a “negative feedback reaction” that actually prevented the equator region from completely freezing over, allowing photosynthesis to occur.

Peltier’s recent findings have found resonance among evolutionary biologists. The late Neoproterozoic period gave rise to arguably the most important period in Earth’s biological history – the Cambrian period. It was during this time when the major groups of animal life exploded onto the fossil record. Rock samples containing evidence of early organic life – ancestors to photosynthetic life – have been dated to before and after glacial periods. The idea that these ancestors to photosynthetic life could have existed during a period when there was no photosynthesis has been a topic of much debate.

“As the temperature of the Neoproterozoic ocean cools and moves towards a snowball state, more organic carbon is converted into carbon dioxide. The oxygen is drawn down out of the atmosphere into the ocean, re-mineralizing the organic matter and forcing respiration,” Peltier explained. “When respiration occurs, it generates carbon dioxide, part of which remains dissolved in the ocean, but part of which is forced out of the ocean into the atmosphere which enhances the greenhouse effect and prevents the cooling.

“The mathematical model supports oscillatory glaciations and de-glaciations on a timescale that’s similar to the timescale that people have argued were appropriate for the Neoproterozoic,” he added.

Doctoral student Yonggang Liu and John Crowley, a former summer research student in Peltier’s lab, now pursuing doctoral studies at Harvard, co-authored the paper, published in Nature late last year.

The study builds on the findings published by Professor Dan Rothman from the Massachusetts Institute of Technology that suggest that the Neoproterozoic ocean was very rich in carbon life and findings published by Peltier on the cover of Nature in 2000 that, for the first time, demonstrated that while huge deep glaciations did exist, a large amount of water near the equator was left unfrozen. At the time, adherents to the “snowball Earth” theory coined the term “slushball Earth” to describe Peltier’s findings.

Possible link found between earthquakes along the Cascadia and San Andreas faults

Cascadia Subduction Zone
Cascadia Subduction Zone

Seismic activity on the southern Cascadia Subduction fault may have triggered major earthquakes along the northern San Andreas Fault, according to new research published by the Bulletin of Seismological Society of America (BSSA). The research refines the recurrence rate for the southern portion of the Cascadia fault to approximately every 220 years for the last 3000 years.

Chris Goldfinger, associate professor of marine geology and geophysics at Oregon State University, and colleagues published their results in the April issue of BSSA as part of a special section on the 1906 San Francisco earthquake. BSSA is published by the Seismological Society of America (SSA), which was created in response to the 1906 earthquake.

Using marine sediment cores collected along the northern California seabed, researchers identified 15 turbidites, which are sediment deposits generated by submarine landslides and commonly triggered by earthquakes. The 15 turbidites, including one associated with the great 1906 earthquake, and the corresponding land paleoseismic record establish an average recurrence rate of approximately 200 – 240 years for the San Andreas Fault.

In a parallel study, they found that during the same period, 13 of these 15 San Andreas earthquakes occurred at almost the same time as earthquakes along the southern Cascadia Subduction Zone, which stretches from northern Vancouver Island to northern California. The marine and land paleoseismic record suggest a recurrence rate of approximately 220 years for the southern Cascadia fault, which is substantially shorter than the 600-year cycle suggested by previous research for full ruptures in Cascadia.

The Cascadia earthquakes also preceded the San Andreas earthquakes by an average of 25 to 45 years. “It’s either an amazing coincidence or one fault triggered the other,” said Goldfinger. The generally larger size of the Cascadia earthquakes, and the timing evidence suggests Cascadia may trigger the San Andreas Two seismic events on the San Andreas were apparently not associated with Cascadia, including the 1906 earthquake which followed the previous Cascadia earthquake by approximately 200 years.

Goldfinger and his colleagues collected core samples that cover the past 10,000 years, and the next step involves analyzing this data for further evidence of a corollary relationship between the plate boundary faults for earlier periods of time. “This type of relationship doesn’t just happen accidentally. We expect the temporal relationship, if correct, to show itself over the longer period of time,” said Goldfinger.

Perhaps the most thoroughly studied seismic event, the 1906 quake continues to fascinate seismologists. BSSA’s special section considers the landmark event, which was initiated along the San Andreas Fault just off the San Francisco coast on April 18, 1906. The strong shaking caused widespread damage along the 300 miles of the fault in northern California, reducing much of San Francisco to rubble.

“The directivity of the ruptures, north to south, which is implied by this study, will have significant meaning for seismic hazard models for San Francisco,” said Goldfinger. The 1906 earthquake, which is an exception to the pattern over the past 3000 years, ruptured in both directions, but mostly from south to north.

“Lessons from the 1906 earthquake should apply to similar faults and earthquakes elsewhere,” writes Brad T. Aagaard, a research geophysicist at the USGS Menlo Park and co-author of the introduction to the special section and two papers that focus on ground motion. “As our understanding of earthquakes evolves and the technology to increase our knowledge develops, there is much to be gained by revisiting older events.

In 1906, approximately 600,000 people lived in the greater Bay Area, about 10 percent of today’s population. Today’s cities have high rise buildings, people travel by car, and five major bridges connect the major cities around the San Francisco Bay.

The special section features new research that characterizes the earthquake source, refines assessments of ground shaking that support higher intensities, and explores the possible effects of a repeat of the 1906 earthquake, or similar-sized earthquakes on the San Andreas Fault.

Research by Aagaard et al., demonstrates how the variability in strong shaking over the San Francisco Bay area observed in 1906 can be attributed to the geologic structure and rupture characteristics. More importantly, by considering other possible rupture scenarios, the Aagaard et al., conclude that future large earthquakes along the San Andreas Fault may subject the San Francisco Bay Area to stronger shaking than occurred in the 1906 earthquake.

One Year After Solomon Islands Disaster, Scientists Realize Geological Barrier to Earthquakes Weaker than Expected

On the one year anniversary of a devastating earthquake and tsunami in the Solomon Islands that killed 52 people and displaced more than 6,000, scientists are revising their understanding of the potential for similar giant earthquakes in other parts of the globe.

Geoscientists from The University of Texas at Austin’s Jackson School of Geosciences and their colleagues report this week that the rupture, which produced an 8.1 magnitude earthquake, broke through a geological province previously thought to form a barrier to earthquakes. This could mean that other sites with similar geological barriers, such as the Cascadia Subduction Zone in northwestern North America, have the potential for more severe earthquakes than once thought.

In an advance online publication in the journal Nature Geoscience, the scientists report that the rupture started on the Pacific seafloor near a spot where two of Earth’s tectonic plates are subducting, or diving below, a third plate.

The two subducting plates-the Australian and Woodlark plates-are also spreading apart and sliding past one another. The boundary between them, called Simbo Ridge, was thought to work as a barrier to the propagation of a rupture because the two plates are sliding under the overriding Pacific plate at different rates, in different directions, and each is likely to have a different amount of built-up stress and friction with the overlying rock. But the boundary did not stop the rupture from spreading from one plate to the other.

“Both sides of that boundary had accumulated elastic strain,” says Fred Taylor, a researcher at the university’s Institute for Geophysics and principal investigator for the project. “Those plates hadn’t had an earthquake for quite a while and they were both ready to rupture. When the first segment ruptured, there was probably stress transferred from one to the other.

“What our work shows is that this is a barrier, but not a reliable one,” says Taylor. In other words, it resists rupturing, but not insurmountably. The work has implications for earthquakes in other parts of the world.

“Cascadia is an important boundary because of its potential for a great earthquake in the future,” says Taylor. “You have these transform faults separating the plates-Juan de Fuca, Gorda and Explorer. If such boundaries are not a barrier to rupture in the Solomons, there’s no reason to believe they are in Cascadia either.”

The last great earthquake along the Cascadia Subduction Zone was in the year 1700. The intensity of the quake has been estimated at around magnitude 9. If it happened today, it could be devastating to people living in the northwestern U.S. and western Canada. The geological record suggests such great quakes occur there every few hundred years.

The scientists were able to piece together where and how the fault near the Solomons ruptured by observing how it affected corals living in shallow water around the islands. Because corals normally grow right up to the low-tide water mark, scientists can readily measure how far they have been displaced up or down by an earthquake. In the case of uplift, scientists measure how far the coral dies back from its previous height as a result of being thrust up out of the water. In the case of subsidence, scientists measure how deep the coral is compared to its usual maximum depth below sea level.

“In many ways the corals are much better than manmade instruments as you don’t need to deploy corals or change their batteries-they just go on measuring uplift and subsidence for you anyhow,” says Taylor.

With funds from the Jackson School of Geosciences, Taylor was able to travel to the Solomons just 10 days after the earthquake to make observations, an extremely swift trip in the world of scientific field work. It was part of a new rapid response capability the Jackson School is developing for research that cannot wait several months for government or foundation grants to be approved.

“The trip wouldn’t have happened without the Jackson School support,” said Taylor. “We are extremely grateful for that.”

Taylor’s co-authors include Cliff Frohlich and Matt Hornbach, also at the Institute for Geophysics, Richard W. Briggs and Aron Meltzner at the California Institute of Technology, Abel Brown at Ohio State University, and Alison K. Papabatu and Douglas Billy at the Department of Mines, Energy and Water in the Solomon Islands.

Continents loss to oceans boosts staying power

Study measures effects of chemical weathering on the composition of continents

New research suggests that the geological staying power of continents comes partly from their losing battle with the Earth’s oceans over magnesium. The research finds continents lose more than 20 percent of their initial mass via chemical reactions involving the Earth’s crust, water and atmosphere. Because much of the lost mass is dominated by magnesium and calcium, continents ultimately gain because the lighter, silicon-rich rock that’s left behind is buoyed up by denser rock beneath the Earth’s crust.

The Earth’s continents seem like fixtures, having changed little throughout recorded human history. But geologists know that continents have come and gone during the Earth’s 4.5 billion years. However, there are more theories than hard data about some of the key processes that govern continents’ lives.

“Continents are built by new rock that wells up from volcanoes in island arcs like Japan,” said lead author Cin-Ty Lee, assistant professor of Earth science at Rice University. “In addition to chemical weathering at the Earth’s surface, we know that some magnesium is also lost due to destabilizing convective forces beneath these arcs.”

Lee’s research, which appeared in the March 24 issue of the Proceedings of the National Academy of Science, marks the first attempt to precisely nail down how much magnesium is lost through two markedly different routes — destabilizing convective forces deep inside the Earth and chemical weathering reactions on its surface. Lee said the project might not have happened at all if it weren’t for some laboratory serendipity.

“I’d acquired some tourmaline samples in San Diego with my childhood mentor, Doug Morton,” Lee said. “We were adding to our rock collections, like kids, but when I got back to the lab, I was curious where the lithium, a major element in tourmaline, needed to make the tourmalines came from. I decided to measure the lithium content in the granitic rocks from the same area, and that’s where this started.”

In examining the lithium content in a variety of rocks, Lee realized that lithium tended to behave like the magnesium that was missing from continents. In fact, the correlation was so close, he realized that lithium could be used as a proxy to find out how much magnesium continents had lost due to chemical weathering.

Continents ride higher than oceans, partly because the Earth’s crust is thicker beneath continents than it is beneath the oceans. In addition, the rock beneath continents is made primarily of silicon-rich minerals like granite and quartz, which are less dense than the magnesium-rich basalt beneath the oceans.

Lee said he always assumed that processes deep in the Earth, beneath the volcanoes that feed continents, accounted for far more magnesium loss than weathering. In particular, a process called “delamination” occurs in subduction zones, places where one piece of the Earth’s crust slides beneath another and gets recycled into the Earth’s magma. As magma wells up beneath continent-feeding volcanoes, it often leaves behind a dense, magnesium-rich layer that ultimately founders back into the Earth’s interior.

In previous research, Lee found that about 40 percent of the magnesium in basaltic magma was lost to delamination. He said he was thus surprised to find that chemical weathering alone accounted for another 20 percent.

“Weathering occurs in just the top few meters or so of the Earth’s crust, and it’s driven by the hydrosphere, the water that moves between the air, land and oceans,” Lee said. “It appears that our planet has continents because we have an active hydrosphere, so if we want to find a hydrosphere on distant planets, perhaps we should look for continents.”

The research was sponsored by the National Science Foundation (NSF) and the Packard Foundation. Co-authors include Morton, of the U.S. Geological Survey (USGS) and the University of California-Riverside; the NSF’s William Leeman, professor emeritus of Earth science at Rice; Ronald Kistler of the USGS; former Rice postdoctorate Arnaud Agranier, now of the University of West Brittany in Brest, France; and former Rice undergraduate Ulyana Horodyskyj, now a graduate student at Brown University.

American West Heating Nearly Twice As Fast As Rest Of World, New Analysis Shows

A remote stretch of the Colorado River from the Escalante Route in the Grand Canyon
A remote stretch of the Colorado River from the Escalante Route in the Grand Canyon

The American West is heating up more rapidly than the rest of the world, according to a new analysis of the most recent federal government temperature figures. The news is especially bad for some of the nation’s fastest growing cities, which receive water from the drought-stricken Colorado River. The average temperature rise in the Southwest’s largest river basin was more than double the average global increase, likely spelling even more parched conditions.

“Global warming is hitting the West hard,” said Theo Spencer of the Natural Resources Defense Council (NRDC). “It is already taking an economic toll on the region’s tourism, recreation, skiing, hunting and fishing activities. The speed of warming and mounting economic damage make clear the urgent need to limit global warming pollution.”

For the report, the Rocky Mountain Climate Organization (RMCO) analyzed new temperature data from the National Oceanic and Atmospheric Administration (NOAA) for 11 western states. For the five-year period 2003-2007 the average temperature in the Colorado River Basin, which stretches from Wyoming to Mexico, was 2.2 degrees Fahrenheit hotter than the historical average for the 20th Century. The temperature rise was more than twice the global average increase of 1.0 degree during the same period. The average temperature increased 1.7 degrees in the entire 11-state western region.

“We are seeing signs of the economic impacts throughout the West,” said study author Stephen Saunders of the Rocky Mountain Climate Organization. “Since 2000 we have seen $2.7 billion in crop loss claims due to drought. Global warming is harming valuable commercial salmon fisheries, reducing hunting activity and revenues, and threatening shorter and less profitable seasons for ski resorts.”

The Colorado River Basin is in the throes of a record drought, shrinking water supplies for upwards of 30 million people in fast-growing Denver, Albuquerque, Las Vegas, Phoenix, Los Angeles and San Diego. Most of the Colorado River’s flow comes from melting snow in the mountains of Wyoming, Utah and Wyoming. Climate scientists predict even more and drier droughts in the future as hotter temperatures reduce the snowpack and increase evaporation.

To date, the governors of Arizona, California, Montana, New Mexico, Oregon, Utah and Washington have signed the Western Climate Initiative (WCI), an agreement to reduce global warming pollution through a market-based system, such as cap-and-trade. The WCI calls for states to reduce their global warming emissions 15 percent below 2005 levels by 2020. Conservationists say the states should commit to meeting these targets, and that there should also be a firm target of an 80 percent reduction by 2050.

A growing chorus of leaders across the political and economic spectrum says more aggressive action is needed at the national level. Supporters say the Lieberman-Warner bill, “America’s Climate Security Act” (S. 2191), is the strongest global warming bill moving through Congress. The bipartisan bill is the first climate legislation ever to be passed out of a Senate committee. The full Senate is expected to vote on the bill by summer, by which time supporters are optimistic about strengthening the bill even further.

“We need strong leadership from western senators to pass America’s Climate Security Act,” said Spencer. “The longer we wait to put a concrete cap on global warming pollution, the greater the threat to all Americans.”

The NRDC-RMCO report, “Warming in the West,” analyzed temperature data from Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming. The report is available online at http://www.nrdc.org/globalWarming/west/contents.asp