Isthmus of Panama formed as result of plate tectonics





Paleogeographic reconstructions of Central America for (A) 20 Ma and (B) 15 Ma.
Paleogeographic reconstructions of Central America for (A) 20 Ma and (B) 15 Ma.

Contrary to previous evidence, a new University of Florida study shows the Isthmus of Panama was most likely formed by a Central American Peninsula colliding slowly with the South American continent through tectonic plate movement over millions of years.



The study, co-authored by Florida Museum of Natural History researchers Michael Kirby, Douglas Jones and Bruce MacFadden, is published in the July 30 issue of PLoS ONE, the online journal of the Public Library of Science. The study uses geologic, chemical and biologic methods to date rocks and fossils found in sides of the Gaillard Cut of the Panama Canal. The results show that instead of being formed by rising and subsiding ocean levels or existing as a string of islands as scientists previously believed, the Isthmus of Panama was first a peninsula of southern Central America before the underlying tectonic plates merged it with South America 4 million years ago.



“Scientists knew Panama was a North American peninsula, possibly as early as 19 million years ago because fossils that are closely related to North American land mammals, such as rhinos, horses, peccaries and dogs have been found in the Panama Canal during ongoing maintenance,” said Kirby, lead author of the study. “But we were not certain when this peninsula first formed and how long it may have existed.”



The canal’s maintenance also exposes sediment layers and marine animal fossils, as well as strata of rocks and clay specific to numerous environments, including lagoon, delta, swamp, woodland and dry tropical forest.



Previous studies placed marine sediment as the youngest layers, suggesting the peninsula was submerged before finally joining with South America. The current study revises the time order of strata, however, and concludes that the Panamanian peninsula joined with South America roughly 4 million years ago.



Deep-sea deposits in one sediment layer suggest a short-lived strait may have existed across the Panama Canal Basin between 21 and 20 million years ago,” said Jones, director of the Florida Museum of Natural History. “However, these short-lived straits probably had little impact on the long-term evolution of Central America’s flora and fauna.”


Kirby explained that because of numerous geologic faults resulting from tectonic plate movement that continues today, there is no area in Panama that allows a full view of the strata making up the land.



“We realized there was a problem with our previous understanding of the stratigraphy, or layering of sediments, in Panama,” Kirby said.



The authors used alternative methods such as strontium isotope dating of fossils and re-analysis of vertebrate fossils to better determine the geologic sequence of the Canal.



“There’s always missing information, like pages out of a book, when it comes to figuring out which layers came first and which were formed later,” Kirby added.



Anthony Coates, a staff scientist emeritus at the Smithsonian Tropical Research Institute in Panama who has extensively studied the geological history of the rise of the Central American isthmus, said the study brings together a diverse array of geologic evidence that convincingly suggests Central America was a peninsula and not a group of islands.



“They have made an important contribution to the land-based geologic evidence of the plate tectonic history of the formation of the Isthmus,” said Coates, who did not participate in the study. “Their results have important consequences for the nature of the global change engendered by the rise and closure of the isthmus.”



One of the major effects of the formation of the Isthmus of Panama was the intensification of the Gulf Stream in the Atlantic Ocean. While the area that is now Panama was still a peninsula, ocean currents moving north along the north coast of South America spilled over to the Pacific Ocean through the wide Central American Seaway, also called the Atrato Seaway. As tectonic plate movement joined the peninsula with South America to form the present-day Isthmus of Panama, equatorial ocean currents between the Atlantic and Pacific were cut off, forcing water northward into the Gulf Stream current.



“The strengthened Gulf Stream, in turn, delivered enough moisture to allow the formation of glaciers across North America,” Kirby said.



The complete text of the study is available on the publication’s Web site, www.plosone.org/doi/pone.0002791.

Mud pots signal possible extension of San Andreas Fault





Most of the major mud pots in the Wister Unit are cicular, steep-sided holes, with varying amounts of bubbling water, spattering mud, and hissing gas.  Some are completely inactive.  Their activity and morphology varies seasonally with the amount of rain and the level of the water table.  It is likely that the surface structure of many pots has been influenced by the earthen rings constructed around them.  Unlike the hot steaming mud pots and mud volcanoes, a few kilometers south in the Salton Sea geothermal field, the temperature of wate and mud in the Wister mud pots is not noticeably elevated.
Most of the major mud pots in the Wister Unit are cicular, steep-sided holes, with varying amounts of bubbling water, spattering mud, and hissing gas. Some are completely inactive. Their activity and morphology varies seasonally with the amount of rain and the level of the water table. It is likely that the surface structure of many pots has been influenced by the earthen rings constructed around them. Unlike the hot steaming mud pots and mud volcanoes, a few kilometers south in the Salton Sea geothermal field, the temperature of wate and mud in the Wister mud pots is not noticeably elevated.

A linear string of mud pots and mud volcanoes suggest surface evidence for a southern extension of the San Andreas Fault that runs through the Salton Sea, according to a paper published in the August issue of the Bulletin of the Seismological Society of America (BSSA).



Researchers David K. Lynch and Kenneth W. Hudnut of USGS report the results of a comprehensive survey of mud pots in the area immediately east of the southeastern-most portion of the Salton Sea in Imperial County, Calif. Using satellite imagery, followed by a physical examination of the land, they identified a cluster of 33 mud pots, mud volcanoes and sink holes which, when plotted, form a clear linear pattern.



Mud pots and mud volcanoes are geothermal features produced when water or gas is forced upward through soil and sediments. Mud pots can assume a variety of forms, typically being depressions or enclosed basins containing gas seeps, bubbling water or viscous mud. Mud pots can also be water-laden and appear as bubbling muddy water. Mud volcanoes, on the other hand, are elevated conical structures composed of accumulations of viscous mud extruded from a central vent. They range from finger-sized to several kilometers across, though the largest in the Salton Sea area are about 2 meters high. Small mud volcanoes on land, ranging from one to 10 feet in height, are usually called mud cones or gryphons and are usually associated with volcanic and seismic activity.


“The presence of a linear field of geothermal features is evidence of a planar rift extending to considerable depth in the crust,” Lynch and Hudnut write.



While geologists have suspected that the San Andreas Fault extended beyond its confirmed terminal point near Bombay Beach, erosion, seismic inactivity and agricultural reshaping of the land have erased any previously identifiable surface evidence to support the theory.



The San Andreas Fault is a plate boundary separating Pacific and North American plates. “This new evidence indicates that the region is more complicated than we previously thought,” Lynch said. “The extension of the San Andreas does not appear to be active. It is probably a very old part of the fault, and helps to explain the larger, more complex transition area between the Imperial fault and San Andreas fault, called the Brawley Seismic Zone.”



The southern portion of the San Andreas Fault is the focus of the Great Southern California ShakeOut, which will be an earthquake drill on 13 Nov. 2008 designed to help prepare local citizens for the next very large earthquake. The scenario will call for a quake with a magnitude of 7.8 that begins in the same area that is the subject of this paper.



Original Paper (PDF) 11 MB

Snapshot of past climate reveals no ice in Antarctica millions of years ago


A snapshot of New Zealand’s climate 40 million years ago reveals a greenhouse Earth, with warmer seas and little or no ice in Antarctica, according to research published this week in the journal Geology.



The study suggests that Antarctica at that time was yet to develop extensive ice sheets. Back then, New Zealand was about 1100 km further south, at the same latitude as the southern tip of South America – so was closer to Antarctica – but the researchers found that the water temperature was 23-25°C at the sea surface and 11-13°C at the bottom.



“This is too warm to be the Antarctic water we know today,” said Catherine (Cat) Burgess from Cardiff University and lead-author of the paper. “And the seawater chemistry shows there was little or no ice on the planet.”



These new insights come from the chemical analysis of exceptionally well preserved fossils of marine micro-organisms called foraminifers, discovered in marine rocks from New Zealand. The researchers tested the calcium carbonate shells from these fossils, which were found in 40 million-year-old sediments on a cliff face at Hampden Beach, South Island.



“Because the fossils are so well preserved, they provide more accurate temperature records” said Cat. “Our findings demonstrate that the water temperature these creatures lived in was much warmer than previous records have shown.”



“Although we did not measure carbon dioxide, several studies suggest that greenhouse gases forty million years ago were similar to those levels that are forecast for the end of this century and beyond.


Our work provides another piece of evidence that, in a time period with relatively high carbon dioxide levels, temperatures were higher and ice sheets were much smaller and likely to have been completely absent.”



The rock sequence from the cliff face covers a time span of 70,000 years and shows cyclical temperature variations with a period of about 18,000 years. The temperature oscillation is likely to be related to the Earth’s orbital patterns.



The research was funded by the Natural Environment Research Council, the Netherlands Organisation for Scientific Research (NWO) and GNS Science, New Zealand.


Original Article



Middle Eocene climate cyclicity in the Southern Pacific: Implications for global ice volume’ is published in the August issue of Geology. (vol.36, no.8, p.651-654; doi:10.1130/G24762A.1)


The authors are:



  • Catherine E. Burgess, Cardiff University (lead author)
  • Paul N. Pearson and Caroline H. Lear, Cardiff University
  • Hugh E.G. Morgans, GNS Science New Zealand
  • Luke Handley and Richard D. Pancost, University of Bristol
  • Stefan Schouten, Royal Netherlands Institute for Sea Research

Scientists search for answers from the carbon in the clouds





Timothy B. Onasch, principal scientist for Aerodyne Research, Inc. (Billerica, Mass.) and Boston College chemistry professor Paul Davidovits check an apparatus they designed to produce uniform soot particles used for aerosols research. - Credit: Lee Pellegrini/Boston College
Timothy B. Onasch, principal scientist for Aerodyne Research, Inc. (Billerica, Mass.) and Boston College chemistry professor Paul Davidovits check an apparatus they designed to produce uniform soot particles used for aerosols research. – Credit: Lee Pellegrini/Boston College

Latest technology examines aerosol particles in the sky



An aerosol mass spectrometer developed by chemists from Aerodyne Research Inc. and Boston College is giving scientists who study airborne particles the technology they need to examine the life cycles of atmospheric aerosols – such as soot – and their impact on issues ranging from climate change to public health.



BC Chemistry Professor Paul Davidovits and Aerodyne Principal Scientist Timothy B. Onasch say their novel spectrometer allows researchers to better understand what happens to these sub-microscopic particles that can absorb and scatter light and influence the lifetime of clouds.



“For scientists looking at climate change, the biggest uncertainty has to do with the effect of aerosol particles in the air,” says Davidovits. “The issue is made that much more complex because aerosols can have different effects on climate. That means the target is constantly shifting.”



The historic role of carbon-laden soot in climate change has been identified by researchers, particularly through ice samples taken from glaciers. Now scientists are focusing on tiny airborne particles of black carbon released into the atmosphere today in order to better understand the lifecycle of these aerosols in the atmosphere.



To that end, nearly 20 researchers from across the country brought other devices to the Davidovits lab this month to test and fine-tune these new tools developed by scientists from universities, industry and national laboratories at the forefront of this path-breaking science of the sky.



Hosted by Davidovits and Onasch, also an associate research professor at BC, the visiting researchers ran streams of laboratory-generated soot through devices able to analyze minute aerosol particles by mass, shape, chemical make-up, even the sound they make when warmed by light – a “pop” inaudible to the human ear.



“This is the cutting edge,” says Dan Lack, a research scientist with the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory in Boulder, Colo. “Much of the technology in this room didn’t exist until a few years ago. And there isn’t another place in the country where you have all this technology running together in concert. It’s a rare opportunity.”



Among the 18 devices involved in the project are Billerica, MA-based Aerodyne’s Aerosol Mass Spectrometer, Boulder-based Droplet Technologies’ Single Particle Soot Photometer, and the NOAA-developed Cavity Ring-Down Aerosol Extinction and Photoacoustic Spectrometers, which shoot a laser beam into black carbon, causing the particle to “pop”, emitting a frequency that’s measured to gauge how much light carbon absorbs.


A technological focal point is a unique soot-particle generating apparatus operated by doctoral student Eben Cross, undergraduate Adam Ahern ’09 and recent graduate Billy Wrobel ’08. The design, construction, and operation of the device were funded by the atmospheric chemistry programs of the Department of Energy and the National Science Foundation.



In the race to determine the scope and speed of climate change and the influence of human activities on it, huge scientific efforts have focused on carbon dioxide gasses emitted largely from the burning of fossil fuels. Scientists believe particulates like black carbon may also contribute significantly to global warming.



For more than 15 years, Davidovits and his Aerodyne colleagues have pioneered the study of soot particles and gas-particle interactions, strengthening an understanding of the role of cloud and aerosol chemistry in acid rain, ozone depletion and climate change.



Aerosols raise temperatures, such as when black particles of soot rise in the sky, absorb sunlight and turn it into heat. Aerosols also can cool by reflecting light away from the earth. Clouds overstuffed with aerosols can inhibit rainfall.



While soot emitted from sources like diesel engines and electric power plants is a focus of study, not all aerosols are man-made. The deserts and arid landscapes of the world produce an estimated 10 to 20 billion tons of mineral aerosols a year. The air is full of biological aerosols as well – microbes, cells, and particles containing organic compounds.



Aerosols are somewhat fleeting. Unlike carbon dioxide, which can remain in the atmosphere for years, aerosols have an atmospheric life of about 10 to 20 days. In that time, they can absorb other molecules that alter their original state.



Measuring the many forms of atmospheric aerosols has led researchers to invent new devices, known as research-grade aerosol particle characterizing instruments, says Davidovits. The challenge now is to fine-tune those instruments in concert with each other in order to set reliable scientific benchmarks for future study.



Linked closely to the atmospheric effects of aerosols is a range of public health concerns, says Onasch.



“There is a need on many fronts – from the climate to public health – for greater understanding of the role aerosol particles play in our lives and what’s happening here is the scientific community rising to meet those needs,” says Onasch.

Scientists Test System to Forecast Flash Floods along Colorado’s Front Range





Communities may soon have advance warning of flash floods. - Credit: U.S. Geological Survey
Communities may soon have advance warning of flash floods. – Credit: U.S. Geological Survey

People near vulnerable creeks, streams, rivers may soon have advance notice



People living near vulnerable creeks and rivers along Colorado’s Front Range may soon get advance notice of potentially deadly floods, thanks to a new forecasting system being tested this summer by the National Center for Atmospheric Research (NCAR) in Boulder, Colo.



Known as the NCAR Front Range Flash Flood Prediction System, it combines detailed atmospheric conditions with information about stream flows to predict floods along specific streams and catchments.



“The goal is to provide improved guidance about the likelihood of a flash flood event many minutes out to an hour or two before the waters start rising,” says NCAR scientist David Gochis, one of the developers of the new forecasting system. “We want to increase the lead time of a forecast, while decreasing the uncertainty about whether a flood will occur.”



Funding to create the system came from the National Science Foundation (NSF), which is NCAR’s sponsor, as well as the National Oceanic and Atmospheric Administration.



“This project is an excellent example of using basic research findings to improve forecasts important to saving lives,” said Cliff Jacobs, program director in NSF’s Division of Atmospheric Sciences.



The Front Range, because of its steep topography and intense summer storms, is unusually vulnerable to summertime flash floods. Such floods have claimed the lives of hundreds of people and accounted for hundreds of millions of dollars in damages throughout the region’s history.



Flash floods are difficult to predict because they happen suddenly, often the result of heavy cloudbursts that may stall over a particular watershed.



Forecasters can give a few hours’ notice that weather conditions might lead to flooding, and radars can detect heavy rain within minutes.



But whether a flood hits a specific river or creek also depends on soil, topographic, and hydrologic conditions that are characteristic to particular watersheds. Thus, emergency managers may not know that a flash flood is imminent until the waters begin to rise.


The goal of the NCAR system is to provide officials at least 30 minutes warning of flash flooding in specific watersheds, and possibly as much as an hour or two.



It is designed to pinpoint whether a particular stream is likely to overflow, as well as forecast the likelihood of flash floods producing events across a larger region.



Scientists will monitor the system’s performance each day, tracking potential flood events from Colorado Springs in the south to Fort Collins in the north.



After this summer’s test of the system, researchers will evaluate its performance and make improvements as needed.



“This summer is a proof-of-concept test,” Gochis says. “If we can show that our system has some reasonable skill in predicting floods, we think officials may become more interested in using it along with their existing suites of tools.”



To predict weather events, the system utilizes National Weather Service radar observations of current conditions and short-term computerized weather forecasts. The weather forecasts are generated by NCAR’s Weather Research and Forecasting (WRF) model, which produces highly detailed simulations of the local atmosphere.



The system integrates the weather information with datasets about hydrology and terrain. These datasets incorporate information about land surface conditions, such as terrain slope, soil composition and surface vegetation. They also include information on stream flow and channel conditions.



By combining information about the land and the atmosphere, the system can project whether an intense storm is likely to stall over a specific area of the Front Range and how that may impact the flow of water on the ground.



“This new system is unique in that it provides a detailed forecast of the location and duration of a severe storm, as well as the watershed’s likely response to the heavy rain,” explains NCAR scientist David Yates.



“Since flash floods are complex and fast-moving events, we need to know about both weather and ground conditions in order to predict them.”

Scientists break record by finding northernmost hydrothermal vent field





The top three feet of a chimney nearly 40 feet tall are visible as the arm of a remotely operated vehicle reaches in to sample fluids. The vent is part of the northernmost hydrothermal vent field yet seen and sampled. - Credit: Centre for Geobiology/U. of Bergen
The top three feet of a chimney nearly 40 feet tall are visible as the arm of a remotely operated vehicle reaches in to sample fluids. The vent is part of the northernmost hydrothermal vent field yet seen and sampled. – Credit: Centre for Geobiology/U. of Bergen

Well inside the Arctic Circle, scientists have found black smoker vents farther north than anyone has ever seen before. The cluster of five vents — one towering nearly four stories in height — are venting water as hot as 570 F.



Dissolved sulfide minerals that solidify when vent water hits the icy cold of the deep sea have, over the years, accumulated around the vent field in what is one of the most massive hydrothermal sulfide deposits ever found on the seafloor, according to Marvin Lilley, a University of Washington oceanographer. He’s a member of an expedition led by Rolf Pedersen, a geologist with the University of Bergen’s Centre for Geobiology, aboard the research vessel G.O. Sars.



The vents are located at 73 degrees north on the Mid-Atlantic Ridge between Greenland and Norway. That’s more than 120 miles from the previous northernmost vents found during a 2005 expedition, also led by Pedersen. Other scientists have detected plumes of water from hydrothermal vents even farther north but have been unable to find the vent fields on the seafloor to image and sample them.



In recent years scientists have been interested in knowing how far north vigorous venting extends. That’s because the ridges where such fields form are so stable up north, usually subject only to what scientists term “ultra-slow” spreading. That’s where tectonic forces are pulling the seafloor apart at a rate as little as 6/10th of an inch in a year. This compares to lower latitudes where spreading can be up to eight times that amount, and fields of hydrothermal vents are much more common.



“We hadn’t expected a lot of active venting on ultra-slow spreading ridges,” Lilley said.


The active chimneys in the new field are mostly black and covered with white mats of bacteria feasting on the minerals emitted by the vents. Older chimneys are mottled red as a result of iron oxidization. All are the result of seawater seeping into the seafloor, coming near fiery magma and picking up heat and minerals until the water vents back into the ocean. The same process created the huge mound of sulfide minerals on which the vents sit. That deposit is about 825 feet in diameter at its base and about 300 feet across on the top and might turn out to be the largest such deposit seen on the seafloor, Lilley said. Additional mapping is needed.



“Given the massive sulfide deposit, the vent field must surely have been active for many thousands of years,” he said.



The field has been named Loki’s Castle partly because the small chimneys at the site looked like a fantasy castle to the scientists. The Loki part refers to a Norwegian god renowned for trickery. A University of Bergen press release about the discovery said Loki “was an appropriate name for a field that was so difficult to locate.”



Indeed this summer’s expedition and the pinpointing of the location of the vents earlier this month follows nearly a decade of research. Finding the actual field involved extensive mapping. It also meant sampling to detect warm water and using optical sensors lowered in the ocean to determine the chemistry, both parts that involved Lilley. He said a key sensor was one developed by Ko-ichi Nakamura of the National Institute of Advanced Science and Technology, Japan, that detects reduced chemicals that are in the water as a result of having been processed through a hydrothermal vent.



A remotely operated vehicle was used to finally find the vents. The difficulties of the task are described in an expedition Web diary, see “Day 17: And then there were vents” at http://www.geobio.uib.no/View.aspx?mid=1062&itemid=90&pageid=1093&moduledefid=71.



The area around the vents was alive with microorganisms and animals. Preliminary observations suggest that the ecosystem around these Arctic vents is diverse and appears to be unique, unlike the vent communities observed elsewhere, the University of Bergen press release said. The expedition included 25 participants from five countries.

Geologist finds clues to ancient chemistry of deep oceans





Paeleontologist Guy Narbonne at his Mistaken Point exploration site on the coast of Newfoundland - Photo by Greg Locke
Paeleontologist Guy Narbonne at his Mistaken Point exploration site on the coast of Newfoundland – Photo by Greg Locke

Queen’s researchers have moved another step closer to explaining changes in the chemistry of the deep oceans – and the sudden appearance of large animal fossils – more than 500 million years ago.



Conducted by Geological Sciences and Geological Engineering professor Guy Narbonne, with an international team of researchers, the study focuses on analyses of iron speciation (iron-bearing minerals that form under different oxygen concentrations) and sulfur isotopes during intense global ice ages. This period is commonly called the “snowball” Earth, 800 to 580 million years ago.



“Our results imply that surface ocean waters of this age were oxygenated, but that deep-sea waters were anoxic (depleted of oxygen) during most of this time,” says Dr. Narbonne, an expert in the early evolution of animals and their ecosystems. The deeper water contained abundant dissolved iron, however – a feature that had not been seen for more than one billion years of Earth history, he adds.



The team’s findings appear on-line in the current edition of Science Express.


The level of dissolved oxygen required for accelerated animal growth did not reach deep-sea waters until about 580 million years ago. This coincided with the first appearance of large, animal-like fossils in deep-water sediments of Newfoundland and northwestern Canada.



In 2002, Dr. Narbonne and his colleagues discovered the world’s oldest complex life forms between layers of sandstone on the southeastern coast of Newfoundland. This pushed back the age of Earth’s earliest known complex life to more than 575 million years ago, soon after the melting of the massive “snowball” glaciers.



The current research team, headed by Donald Canfield from the University of Southern Denmark, also includes: Simon Poulton (Newcastle University), Andrew Knoll (Harvard), Gerry Ross (Kula, Hawaii) and Harald Strauss (Justus-Liebig-Universitat Giessen).

Future snowmelt in West twice as early as expected; threatens ecosystems and water reserves





Timing of runoff
Timing of runoff

According to a new study, global warming could lead to larger changes in snowmelt in the western United States than was previously thought, possibly increasing wildfire risk and creating new water management challenges for agriculture, ecosystems and urban populations.



Researchers, including a Purdue University professor of earth and atmospheric sciences, discovered that a critical surface temperature feedback is twice as strong as what had been projected by earlier studies.



The high-resolution climate model used by the team was better able to reproduce the complex topography of the western United States and capture details of the effect of snow cover on the climate system, as well as the historical record of runoff.



The findings will be published in an upcoming issue of Geophysical Research Letters and are now available online at the journal’s Web site.



Noah Diffenbaugh, senior author of the paper and an associate professor of earth and atmospheric sciences at Purdue, said the influence of melting snow on regional climate is far greater than that of increased greenhouse gases alone.



“The heat trapping from elevated greenhouse gases triggers the warming, but the additional warming caused by the loss of snow is what really creates the big changes in surface runoff,” said Diffenbaugh, who also is a member of Purdue’s Climate Change Research Center. “Scientists have known about this general effect for years. The big surprise here is how much the complex topography plays a role, essentially doubling the threat to water resources in the West.”



Sara A. Rauscher, visiting scientist at the Abdus Salam International Centre for Theoretical Physics in Trieste, Italy, and lead author on the paper, said the melting snow contributes to a feedback loop that accelerates warming.



“Because snow is more reflective than the ground or vegetation beneath it, it keeps the surface temperatures lower by reflecting energy from the sun,” Rauscher said. “When snow melts or does not accumulate in the first place, more solar energy is absorbed by the ground, warming the surface. A feedback loop is created because the warmer ground then makes it more difficult for snow to accumulate and perpetuates the effect.”



The amount and timing of the runoff from snowmelt is critical to the success of water management in the western United States. Water resources for the area are reliant on snow acting as a natural reservoir during the cold season that melts and releases water in the warm season.



Changes in this timing could create problems in meeting the increasing demand for water in large urban and agricultural areas during the hottest summer months, Diffenbaugh said.


“If the snow melts earlier or if it comes as rainfall instead, it would create a strain on infrastructure,” he said. “The current system relies on water being stored in the mountains as snow. So earlier runoff could mean too much water for the reservoirs early in the year and not enough available later in the year.”



Gregg M. Garfin, deputy director for science translation and outreach at the Institute for the Study of Planet Earth at the University of Arizona, said dry summers could lead to more severe wildfires and changes in the ecosystems of the West.



“Early snowmelt and warmer soil temperatures could result in further massive forest mortality and an increased risk of wildfire activity,” Garfin said. “If these projections become reality, then the ecosystems of the northern and central Rockies will undergo dramatic changes with ramifications for wildlife habitat, fire potential, soil erosion and tourism.”



The study suggests a substantial change in the runoff season, with the peak date more than two months earlier than today in some regions, Diffenbaugh said.



“During the past 50 years, the peak runoff time has moved 10 to 15 days earlier,” he said. “It is not surprising that as we look to the future, the projected changes are much greater than the historical changes. The increase in greenhouse gas emissions has been relatively small for the past 50 years compared with where we are headed over the next several decades if substantial changes in energy technology and population growth do not occur.”



The researchers also compared the climate model to historical records and found that it had a high level of agreement with historical data and observed trends.



“One of the most important contributions of this work is the remarkable agreement between the climate model and the observations of the recent past,” Diffenbaugh said. “This agreement should increase confidence not only in these particular projections of future changes, but also of climate model projections in general.”



Additional study co-authors are Jeremy S. Pal of Loyola Marymount University and Michael Benedetti of the University of North Carolina at Wilmington. The research was funded in part by grants from the National Science Foundation.



The Purdue Climate Change Research Center is affiliated with Purdue’s Discovery Park. The center promotes and organizes research and education on global climate change and studies its impact on agriculture, natural ecosystems and society. It was established in 2004 to support Purdue in research and education on regional-scale climate change, its impacts and mitigation, and adaptation strategies. The center serves as a hub for a range of activities beyond scientific research, including teaching, public education and the development of public policy recommendations.



The high-resolution climate model simulations were conducted using computing resources in Purdue’s Rosen Center for Advanced Computing. The Rosen Center is a research computing center named in memory of Saul Rosen, who served as director of Purdue’s Computing Center from 1968-87 and helped establish Purdue as a pioneering academic institution in high-performance computing. The Rosen Center is a part of Information Technology at Purdue, which is responsible for planning and coordinating the central computing and telecommunications systems on the West Lafayette campus.



The Abdus Salam International Centre for Theoretical Physics was founded in 1964 by Nobel Laureate Abdus Salam. The center operates under a tripartite agreement among the Italian Government and two U.N. agencies, UNESCO and IAEA. Its mission is to foster advanced studies and research, especially in developing countries. While the name of the center reflects its beginnings, its activities today include geophysical and environmental sciences.

Scientists offer new explanation for monsoon development


Geoscientists at the California Institute of Technology have come up with a new explanation for the formation of monsoons, proposing an overhaul of a theory about the cause of the seasonal pattern of heavy winds and rainfall that essentially had held firm for more than 300 years.



The traditional idea of monsoon formation was developed in 1686 by English astronomer and mathematician Edmond Halley, namesake of Halley’s Comet. In Halley’s model, monsoons are viewed as giant sea-breeze circulations, driven by the differences in heat capacities between land and ocean surfaces that, upon heating by sunlight, lead to temperature differences between warmer land and cooler ocean surfaces–for example, between the Indian subcontinent and the oceans surrounding it.



“These circulations form overturning cells, with air flowing across the equator toward the warmer land surface in the summer hemisphere, rising there, flowing back toward and across the equator aloft, and sinking in the winter hemisphere,” explains Tapio Schneider, associate professor of environmental science and engineering at Caltech.



A different explanation is offered by Schneider and Simona Bordoni of the National Center for Atmospheric Research in Boulder, Colorado. The duo used a computer-generated, water-covered, hypothetical earth (an “aquaplanet”) to simulate monsoon formation and found that differences in heat capacities between land and sea were not necessary. Bordoni was a Moore Postdoctoral Scholar at Caltech and will return to Caltech as an assistant professor in 2009.


Monsoons arise instead because of an interaction between the tropical circulation and large-scale turbulent eddies generated in the atmosphere in middle latitudes. These eddies, which can span more than 300 miles across, form the familiar systems that govern the weather in middle latitudes.



The eddies, Schneider says, are “basically large waves, which crash into the tropical circulation. They ‘break,’ much like water waves on the beach, and modify the circulation as a result of the breaking. There are feedbacks between the circulation, the wind pattern associated with it in the upper atmosphere, and the propagation characteristics of the waves, which make it possible for the circulation to change rapidly.” This can quickly generate the characteristic high surface winds and heavy rainfall of the monsoon.



Bordoni adds: “These feedbacks provide one possible explanation for the rapidity of monsoon onset, which had been a long-standing conundrum in the traditional view of monsoons,” because substantial differences between land and sea temperatures can only develop slowly through heating by sunlight.



Although the results won’t immediately produce better forecasts of impending monsoons, Schneider says, “in the long run, a better understanding of monsoons may lead to better predictions with semi-empirical models, but much more work needs to be done.”



The paper, “Monsoons as eddy-mediated regime transitions of the tropical overturning circulation,” appears in the advance online edition of Nature Geosciences. The work was supported by the Davidow Discovery Fund, a David and Lucile Packard Fellowship, a Moore Postdoctoral Fellowship, and the National Science Foundation. The National Center for Atmospheric Research is sponsored by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this publication are those of the author and do not necessarily reflect the views of the National Science Foundation.

The greatest story of man and permafrost





Alyeska Pipeline Service Company Engineer Elden Johnson provides a lecture underneath a portion of the trans-Alaska oil pipeline. - Photo by Ned Rozell
Alyeska Pipeline Service Company Engineer Elden Johnson provides a lecture underneath a portion of the trans-Alaska oil pipeline. – Photo by Ned Rozell

In 1973, Elden Johnson was a young engineer working on one of the most ambitious and uncertain projects in the world–an 800-mile steel pipeline that carried warm oil over frozen ground. Thirty-five years later, Johnson looked back at what he called “the greatest story ever told of man’s interaction with permafrost.”



Strung over and beneath the surface of Alaska from Prudhoe Bay to Valdez, the trans-Alaska pipeline, at 31 years old, is entering its second lifetime. The four-foot in diameter, half-inch-thick steel pipe had an original design lifespan of 30 years. The State of Alaska and the U.S. Department of the Interior recently gave the pipeline the green light for another 30 years of operation.



“It’s like a car,” said Johnson, who works for Alyeska Pipeline Service Company, while standing under the pipeline near Fairbanks during a recent permafrost conference lecture. “As long as you maintain it, it’ll continue to work.”



Permafrost, frozen ground that is a relic of the last ice age, exists beneath about 75 percent of the pipeline’s 800-mile route. When ice-rich permafrost thaws, the ground slumps, causing problems for structures above.



After the 1969 oil discovery at Prudhoe Bay, developers unfamiliar with Alaska wanted to bury the entire supply of Japanese-made pipe. After a review by people who knew the dangers of building on permafrost, a legion of workers constructed a pipeline buried for 380 miles and–in areas of permafrost–built above the ground on platforms for 420 miles.



The initial design was good, but not perfect, Johnson said. He remembered during construction when he and others were inspecting the ground from the Yukon River to Coldfoot. They found unstable permafrost and recommended re-design of sections of the pipeline. Instead of conventional buried pipeline, the engineers called for more expensive and time-consumptive, above-ground pipeline.


“We changed the design for at least 20 percent of that distance,” he said. “They were gut-wrenching decisions potentially impacting the startup schedule.”



The call to elevate more than half the pipeline turned out to be a good one. Even though engineers bored holes in the ground about every 800 feet to check for permafrost, they didn’t find it all. When the pipeline was two years old in 1979, the pipe buckled and leaked in two buried sections because of thawed permafrost. In both cases, the pipeline, which carried oil that left the ground in Prudhoe Bay as warm as 145 degrees Fahrenheit, caused about four feet of settlement. Engineers fixed those and other problems. The two leaks in 1979 are still the only spills caused by permafrost.



Alyeska workers check the pipeline each year for signs of settling and proper operation of the heat pipes that help keep the support posts of the above-ground pipeline anchored in frozen ground. The buried pipeline has become more stable over its 31 years as the rapid thawing of early years has settled down.



“The risk to the buried pipeline right now is becoming minimal,” Johnson said.



The pipeline has delivered more than 16 billion barrels of oil since its startup in June 1977, with two brief shutdowns due to permafrost. Johnson estimated permafrost-related maintenance has totaled about 5-to-10 percent of the operating costs over the life of the pipeline.



“It’s the cost of doing business in the Arctic,” he said



With a career of work on the massive engineering project Johnson calls “a beautiful thing,” he is retiring from Alyeska this winter. His mind won’t stray far from the challenges of building pipelines across cold country. His daughter Katie, a mechanical engineering graduate from the University of Alaska Fairbanks, has just signed on to help work with the natural gas pipeline from the North Slope southward.



“It’s kind of a second-generation opportunity to look at the next pipeline,” Johnson said.