How Aerosols Contribute To Climate Change

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ScienceDaily (June 23, 2009) — What happens in Vegas may stay in Vegas, but what happens on the way there is a different story.

As imaged by Lynn Russell, a professor of atmospheric chemistry at Scripps Institution of Oceanography at UC San Diego, and her team, air blown by winds between San Diego and Las Vegas gives the road to Sin City a distinctive look.
The team has sampled air from the tip of the Scripps Pier since last year, creating a near real-time record of what kinds of particles — from sea salt to car exhaust — are floating around at any given time. Add data about wind speed and direction and the scientists can tell where particles came from and can map their pathways around Southern California.
When Russell and her students put it all together, the atmosphere of greater San Diego comes alive in colors representing the presence of different airborne chemical compounds in aerosol form. One streak of deep red draws a distinct line from the pier that sometimes extends all the way to Las Vegas. The red denotes organic mass, a carbon-based component of vehicular and industrial emissions that pops up on Russell’s readouts frequently. Plot the streak on a road atlas and it reveals the daily life of pollution in Southern California. For one stretch of time, it neatly traced Interstate 15 all the way past the California-Nevada border.
“We were really surprised,” said Russell. “We did not expect to have such consistent winds for the selected study days.”
The hunt for various types of aerosols is helping Russell draw new kinds of global maps, ones that depict what organic compounds—whether natural or from sources such as Southern California traffic and industries—could do to affect rainfall, snowfall, atmospheric warming and cooling, and a host of other climate phenomena. Russell is part of an effort that involves several researchers at Scripps and UCSD and around the world. Collectively they are attempting to address a human-caused phenomenon in the Earth system scarcely considered before the last decade.
Aerosol research is considered one of the most critical frontiers of climate change science, much of which is devoted to the creation of accurate projections of future climate. These projections are generated by computer models — simulations of phenomena such as warming patterns, sea level fluctuations, or drought trends. The raw data for the models can come from historical records of climate basics like temperature and precipitation, but scientists often must rely on incomplete data and best guesses to represent more complex phenomena. The more such uncertainty goes into a model, the greater its margin of error becomes, making it less reliable as a guide for forecasts and adaptive actions.
Among these complex phenomena, the actions of aerosols are what some researchers consider the field’s holy grail, representing the biggest barrier to producing accurate representations of climate. In fact, the Intergovernmental Panel on Climate Change in 2007 specifically listed the effect of aerosols on cloud formation as the largest source of uncertainty in present-day climate models.
Bits of dust, sea salt, the remnants of burned wood, and even living things like bacteria all add to the mix of aerosols that create the skeletons on which clouds form. Around these particles, water and ice condense and cluster into cloud masses. The size and number of each of these droplets determine whether the clouds can produce rain or snow.
The aerosols are also influencing climate in other ways. Diesel exhaust, industrial emissions, and the smoke from burning wood and brush eject myriad bits of black carbon, usually in the form of soot, into the sky and form so-called “brown clouds” of smog. This haze has a dual heating and cooling effect. The particles absorb heat and make the air warmer at the altitudes to which they tend to rise but they also deflect sunlight back into space. This shading effect cools the planet at ground level.
The Arctic Circle is one of the places in the world most sensitive to changes in the mix of aerosols. Since the beginnings of the Industrial Revolution, scientists and explorers have noted the presence of the Arctic haze, a swirl of pollution that appears when sunlight returns after a winter of darkness. The presence of smog over a mostly uninhabited region leads many scientists to believe it is the reason the Arctic is experiencing the most rapid climate-related changes in the world. The haze now lingers for a longer period of time every year. It may be contributing to the forces now causing a meltdown of Arctic ice, a release of methane once stored in permafrost, and a host of ecological changes affecting the spectrum of organisms from mosquitoes to polar bears.
Russell has taken part in two recent analyses of polar air to understand where its imported aerosols come from and how the chemical components of those aerosols could be affecting temperature and cloud formation. From a research vessel in the Norwegian Sea and via continuous measurements from a ground station in Barrow, Alaska, Russell’s team is analyzing particles likely to have been blown to the Arctic from Europe and Asia. Her group has just compiled a full season of air samples fed through intake valves onto filters collected at Barrow.
With it, she believes she has proven what colleagues have previously theorized about where the particles are coming from. She is especially interested in organic particles—aerosols containing carbon supplied either by natural sources such as ocean or land plants or by human sources. Work in her group has shown that organics in the spring haze carry a signature consistent with dust and biomass burning taking place most likely in Siberia. The chemical signature changes in other seasons, revealing itself in infrared spectroscopy readings to be the product of aerosols from natural sources.
The aerosols could be influencing how much snowfall the Arctic gets and keeps. Human-produced aerosols are thought to stifle precipitation in some areas but may provide the impetus for torrential rain in others depending on their chemical make-up. Even if the Asian aerosols are not affecting precipitation, however, Russell said they appear to cool the Arctic atmosphere by deflecting light into space. At the same time, there is strong evidence that they are accelerating ice melt in the Arctic by darkening and heating ice once they fall to the ground the way a dark sweater makes its wearer hotter on a sunny day than does a white sweater.
Russell has been part of another collaborative effort launched in 2008, the International Polar Year, that created chemical profiles of relatively untainted air off the Norwegian west coast, which is only occasionally tinged by European smog. She has also teamed with collaborators at Scripps, NOAA and other universities to profile aerosols around Houston, Texas, and Mexico City.
In the latter two projects, she has provided evidence that agriculture adds more to the aerosol mix in an oil town like Houston than previously thought and that organic particles in Mexico City, rising from the smoke of street vendors and exhaust of cars driving on gas formulated differently than in the United States, glom on to dust in a different manner than American pollution to create aerosols with distinct chemical structures. Figuring out what they do locally and regionally is the next step.
Russell collaborates with a number of other faculty at UCSD whose research also focuses on aerosols, such as Kim Prather, an atmospheric chemistry professor with joint appointments at Scripps and the UCSD Department of Chemistry and Biochemistry. Russell and Prather are comparing their results form Mexico City in an effort to better understand the sources of aerosols in the atmosphere.
“We are trying to understand the major sources of aerosols in our atmosphere and how they affect the overall temperature of our planet; as opposed to greenhouse gases which we know are warming, aerosols can cool or warm depending on their composition and where they are located in the atmosphere," said Prather. Like Russell, Prather also studies long-range transport of aerosols from terrestrial and marine sources. Prather and Russell have worked together on several other projects and recently helped form the Aerosol Chemistry and Climate Institute, a collaboration between Scripps and the Department of Energy’s Pacific Northwest National Laboratory.
For her most comprehensive study, Russell need only to make her shortest journey to the end of Scripps Pier. It is possible that aerosol journeys of a thousand miles or more might be explained by shorter commutes between Southern California counties. Complete analysis of the Interstate 15 data suggests Vegas might not be a source of dirtiness after all. Using data collected over longer time periods, Russell’s pollution map of local counties now suggests organic human-made aerosols might just be blowing toward Nevada from San Bernardino and Riverside then back toward San Diego as winds shift. Russell employs a suite of complementary measurements at the pier to characterize short- and long-term aerosol trends. Those are combined with particle profiles made by Prather’s group and collaborators whose numbers are growing out of necessity.
“Understanding the big picture is the only way we’re going to be able to reduce the uncertainty associated with aerosol particles and their effects on climate,” said Russell. “There are so many parameters, there’s no one instrument or even one person who can do all of it at once.”
Adapted from materials provided by University of California, San Diego, via Newswise.

Carbon Dioxide Higher Today Than Last 2.1 Million Years

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ScienceDaily (June 21, 2009) — Researchers have reconstructed atmospheric carbon dioxide levels over the past 2.1 million years in the sharpest detail yet, shedding new light on its role in the earth's cycles of cooling and warming.

The study, in the June 19 issue of the journal Science, is the latest to rule out a drop in CO2 as the cause for earth's ice ages growing longer and more intense some 850,000 years ago. But it also confirms many researchers' suspicion that higher carbon dioxide levels coincided with warmer intervals during the study period.
The authors show that peak CO2 levels over the last 2.1 million years averaged only 280 parts per million; but today, CO2 is at 385 parts per million, or 38% higher. This finding means that researchers will need to look back further in time for an analog to modern day climate change.
In the study, Bärbel Hönisch, a geochemist at Lamont-Doherty Earth Observatory, and her colleagues reconstructed CO2 levels by analyzing the shells of single-celled plankton buried under the Atlantic Ocean, off the coast of Africa. By dating the shells and measuring their ratio of boron isotopes, they were able to estimate how much CO2 was in the air when the plankton were alive. This method allowed them to see further back than the precision records preserved in cores of polar ice, which go back only 800,000 years.
The planet has undergone cyclic ice ages for millions of years, but about 850,000 years ago, the cycles of ice grew longer and more intense—a shift that some scientists have attributed to falling CO2 levels. But the study found that CO2 was flat during this transition and unlikely to have triggered the change.
"Previous studies indicated that CO2 did not change much over the past 20 million years, but the resolution wasn't high enough to be definitive," said Hönisch. "This study tells us that CO2 was not the main trigger, though our data continues to suggest that greenhouse gases and global climate are intimately linked."
The timing of the ice ages is believed to be controlled mainly by the earth's orbit and tilt, which determines how much sunlight falls on each hemisphere. Two million years ago, the earth underwent an ice age every 41,000 years. But some time around 850,000 years ago, the cycle grew to 100,000 years, and ice sheets reached greater extents than they had in several million years—a change too great to be explained by orbital variation alone.
A global drawdown in CO2 is just one theory proposed for the transition. A second theory suggests that advancing glaciers in North America stripped away soil in Canada, causing thicker, longer lasting ice to build up on the remaining bedrock. A third theory challenges how the cycles are counted, and questions whether a transition happened at all.
The low carbon dioxide levels outlined by the study through the last 2.1 million years make modern day levels, caused by industrialization, seem even more anomalous, says Richard Alley, a glaciologist at Pennsylvania State University, who was not involved in the research.
"We know from looking at much older climate records that large and rapid increase in CO2 in the past, (about 55 million years ago) caused large extinction in bottom-dwelling ocean creatures, and dissolved a lot of shells as the ocean became acidic," he said. "We're heading in that direction now."
The idea to approximate past carbon dioxide levels using boron, an element released by erupting volcanoes and used in household soap, was pioneered over the last decade by the paper's coauthor Gary Hemming, a researcher at Lamont-Doherty and Queens College. The study's other authors are Jerry McManus, also at Lamont; David Archer at the University of Chicago; and Mark Siddall, at the University of Bristol, UK.
Funding for the study was provided by the National Science Foundation.
Journal reference:
. Atmospheric Carbon Dioxide Concentrations Across the Mid-Pleistocene Transition. Science, June 19, 2009
Adapted from materials provided by The Earth Institute at Columbia University.

Ocean Circulation Doesn't Work As Expected

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This model of North Atlantic currents has been called into question by new data from Duke University and the Woods Hole Oceanographic Institution. Image: Archana Gowda, Duke
(PhysOrg.com) -- The familiar model of Atlantic ocean currents that shows a discrete "conveyor belt" of deep, cold water flowing southward from the Labrador Sea is probably all wet.

New research led by Duke University and the Woods Hole Oceanographic Institution relied on an armada of sophisticated floats to show that much of this water, originating in the sea between Newfoundland and Greenland, is diverted generally eastward by the time it flows as far south as Massachusetts. From there it disburses to the depths in complex ways that are difficult to follow.
A 50-year-old model of ocean currents had shown this southbound subsurface flow of cold water forming a continuous loop with the familiar northbound flow of warm water on the surface, called the Gulf Stream.
"Everybody always thought this deep flow operated like a conveyor belt, but what we are saying is that concept doesn't hold anymore," said Duke oceanographer Susan Lozier. "So it's going to be more difficult to measure these climate change signals in the deep ocean."
And since cold Labrador seawater is thought to influence and perhaps moderate human-caused climate change, this finding may affect the work of global warming forecasters.
"To learn more about how the cold deep waters spread, we will need to make more measurements in the deep ocean interior, not just close to the coast where we previously thought the cold water was confined," said Woods Hole's Amy Bower.
Lozier, a professor of physical oceanography at Duke's Nicholas School of the Environment and Bower, a senior scientist in the department of physical oceanography at the Woods Hole Institution, are co-principal authors of a report on the findings to be published in the May 14 issue of the research journal Nature.
Their research was supported by the National Science Foundation.
Climatologists pay attention to the Labrador Sea because it is one of the starting points of a global circulation pattern that transports cold northern water south to make the tropics a little cooler and then returns warm water at the surface, via the Gulf Stream, to moderate temperatures of northern Europe.

Since forecasters say effects of global warming are magnified at higher latitudes, that makes the Labrador Sea an added focus of attention. Surface waters there absorb heat-trapping carbon dioxide from the atmosphere. And a substantial amount of that CO2 then gets pulled underwater where it is no longer available to warm Earth's climate.
"We know that a good fraction of the human caused carbon dioxide released since the Industrial revolution is now in the deep North Atlantic" Lozier said. And going along for the ride are also climate-caused water temperature variations originating in the same Labrador Sea location.
The question is how do these climate change signals get spread further south? Oceanographers long thought all this Labrador seawater moved south along what is called the Deep Western Boundary Current (DWBC), which hugs the eastern North American continental shelf all the way to near Florida and then continues further south.
But studies in the 1990s using submersible floats that followed underwater currents "showed little evidence of southbound export of Labrador sea water within the Deep Western Boundary Current (DWBC)," said the new Nature report.
Scientists challenged those earlier studies, however, in part because the floats had to return to the surface to report their positions and observations to satellite receivers. That meant the floats' data could have been "biased by upper ocean currents when they periodically ascended," the report added.
To address those criticisms, Lozier and Bower launched 76 special Range and Fixing of Sound floats into the current south of the Labrador Sea between 2003 and 2006. Those "RAFOS" floats could stay submerged at 700 or 1,500 meters depth and still communicate their data for a range of about 1,000 kilometers using a network of special low frequency and amplitude seismic signals.
But only 8 percent of the RAFOS floats' followed the conveyor belt of the Deep Western Boundary Current, according to the Nature report. About 75 percent of them "escaped" that coast-hugging deep underwater pathway and instead drifted into the open ocean by the time they rounded the southern tail of the Grand Banks.
Eight percent "is a remarkably low number in light of the expectation that the DWBC is the dominant pathway for Labrador Sea Water," the researchers wrote.
Studies led by Lozier and other researchers had previously suggested cold northern waters might follow such "interior pathways" rather than the conveyor belt in route to subtropical regions of the North Atlantic. But "these float tracks offer the first evidence of the dominance of this pathway compared to the DWBC."
Since the RAFOS float paths could only be tracked for two years, Lozier, her graduate student Stefan Gary, and German oceanographer Claus Boning also used a modeling program to simulate the launch and dispersal of more than 7,000 virtual "efloats" from the same starting point.
"That way we could send out many more floats than we can in real life, for a longer period of time," Lozier said.
Subjecting those efloats to the same underwater dynamics as the real ones, the researchers then traced where they moved. "The spread of the model and the RAFOS float trajectories after two years is very similar," they reported.
"The new float observations and simulated float trajectories provide evidence that the southward interior pathway is more important for the transport of Labrador Sea Water through the subtropics than the DWBC, contrary to previous thinking," their report concluded.
"That means it is going to be more difficult to measure climate signals in the deep ocean," Lozier said. "We thought we could just measure them in the Deep Western Boundary Current, but we really can't."
Source: Duke University (news : web)

Changes In The Sun Are Not Causing Global Warming, New Study Shows

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ScienceDaily (May 12, 2009) — With the U.S. Congress beginning to consider regulations on greenhouse gases, a troubling hypothesis about how the sun may impact global warming is finally laid to rest.

Carnegie Mellon University's Peter Adams along with Jeff Pierce from Dalhousie University in Halifax, Canada, have developed a model to test a controversial hypothesis that says changes in the sun are causing global warming.
The hypothesis they tested was that increased solar activity reduces cloudiness by changing cosmic rays. So, when clouds decrease, more sunlight is let in, causing the earth to warm. Some climate change skeptics have tried to use this hypothesis to suggest that greenhouse gases may not be the global warming culprits that most scientists agree they are.
In research published in Geophysical Research Letters, and highlighted in the May 1 edition of Science, Adams and Pierce report the first atmospheric simulations of changes in atmospheric ions and particle formation resulting from variations in the sun and cosmic rays. They find that changes in the concentration of particles that affect clouds are 100 times too small to affect the climate.
"Until now, proponents of this hypothesis could assert that the sun may be causing global warming because no one had a computer model to really test the claims," said Adams, a professor of civil and environmental engineering at Carnegie Mellon.
"The basic problem with the hypothesis is that solar variations probably change new particle formation rates by less than 30 percent in the atmosphere. Also, these particles are extremely small and need to grow before they can affect clouds. Most do not survive to do so," Adams said.
Despite remaining questions, Adams and Pierce feel confident that this hypothesis should be laid to rest. "No computer simulation of something as complex as the atmosphere will ever be perfect," Adams said. "Proponents of the cosmic ray hypothesis will probably try to question these results, but the effect is so weak in our model that it is hard for us to see this basic result changing."
Journal references:
J. R. Pierce and P. J. Adams. Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates? Geophys. Res. Lett., 2009; (in press) DOI: 10.1029/2009GL037946
Richard A. Kerr. Study Challenges Cosmic Ray-Climate Link. Science, 2009; 324 (5927): 576 DOI: 10.1126/science.324_576b
Adapted from materials provided by Carnegie Mellon University.

Origin Of 'Breathable' Atmosphere Half A Billion Years Ago Discovered

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http://www.sciencedaily.com/releases/2007/10/071029094320.htm

ScienceDaily (Oct. 30, 2007) — Ohio State University geologists and their colleagues have uncovered evidence of when Earth may have first supported an oxygen-rich atmosphere similar to the one we breathe today.

The study suggests that upheavals in the earth's crust initiated a kind of reverse-greenhouse effect 500 million years ago that cooled the world's oceans, spawned giant plankton blooms, and sent a burst of oxygen into the atmosphere.
That oxygen may have helped trigger one of the largest growths of biodiversity in Earth's history.
Matthew Saltzman, associate professor of earth sciences at Ohio State, reported the findings October 28 at the meeting of the Geological Society of America in Denver.
For a decade, he and his team have been assembling evidence of climate change that occurred 500 million years ago, during the late Cambrian period. They measured the amounts of different chemicals in rock cores taken from around the world, to piece together a complex chain of events from the period.
Their latest measurements, taken in cores from the central United States and the Australian outback, revealed new evidence of a geologic event called the Steptoean Positive Carbon Isotope Excursion (SPICE).
Amounts of carbon and sulfur in the rocks suggest that the event dramatically cooled Earth's climate over two million years -- a very short time by geologic standards. Before the event, the Earth was a hothouse, with up to 20 times more carbon dioxide in the atmosphere compared to the present day. Afterward, the planet had cooled and the carbon dioxide had been replaced with oxygen. The climate and atmospheric composition would have been similar to today.
“If we could go back in time and walk around in the late Cambrian, this seems to be the first time we would have felt at home,” Saltzman said. “Of course, there was no life on land at the time, so it wouldn't have been all that comfortable.”
The land was devoid of plants and animals, but there was life in the ocean, mainly in the form of plankton, sea sponges, and trilobites. Most of the early ancestors of the plants and animals we know today existed during the Cambrian, but life wasn't very diverse.
Then, during the Ordovician period, which began around 490 million years ago, many new species sprang into being. The first coral reefs formed during that time, and the first true fish swam among them. New plants evolved and began colonizing land.
“If you picture the evolutionary ‘tree of life,' most of the main branches existed during the Cambrian, but most of the smaller branches didn't get filled in until the Ordovician,” Saltzman said. “That's when animal life really began to develop at the family and genus level.” Researchers call this diversification the “Ordovician radiation.”
The composition of the atmosphere has changed many times since, but the pace of change during the Cambrian is remarkable. That's why Saltzman and his colleagues refer to this sudden influx of oxygen during the SPICE event as a “pulse” or “burst.”
“After this pulse of oxygen, the world remained in an essentially stable, warm climate, until late in the Ordovician,” Saltzman said.
He stopped short of saying that the oxygen-rich atmosphere caused the Ordovician radiation.
“We know that oxygen was released during the SPICE event, and we know that it persisted in the atmosphere for millions of years -- during the time of the Ordovician radiation -- so the timelines appear to match up. But to say that the SPICE event triggered the diversification is tricky, because it's hard to tell exactly when the diversification started,” he said.
“We would need to work with paleobiologists who understand how increased oxygen levels could have led to a diversification. Linking the two events precisely in time is always going to be difficult, but if we could link them conceptually, then it would become a more convincing story.”
Researchers have been trying to understand the sudden climate change during the Cambrian period ever since Saltzman found the first evidence of the SPICE event in rock in the American west in 1998. Later, rock from a site in Europe bolstered his hypothesis, but these latest finds in central Iowa and Queensland, Australia, prove that the SPICE event occurred worldwide.
During the Cambrian period, most of the continents as we know them today were either underwater or part of the Gondwana supercontinent, Saltzman explained. Tectonic activity was pushing new rock to the surface, where it was immediately eaten away by acid rain. Such chemical weathering pulls carbon dioxide from the air, traps the carbon in sediments, and releases oxygen -- a kind of greenhouse effect in reverse.
“From our previous work, we knew that carbon was captured and oxygen was released during the SPICE event, but we didn't know for sure that the oxygen stayed in the atmosphere,” Saltzman said.
They compared measurements of inorganic carbon -- captured during weathering -- with organic carbon -- produced by plankton during photosynthesis. And because plankton contain different ratios of the isotopes of carbon depending on the amount of oxygen in the air, the geologists were able to double-check their estimates of how much oxygen was released during the period, and how long it stayed in the atmosphere.
They also studied isotopes of sulfur, to determine whether much of the oxygen being produced was re-captured by sediments.
It wasn't.
Saltzman explained the chain of events this way: Tectonic activity led to increased weathering, which pulled carbon dioxide from the air and cooled the climate. Then, as the oceans cooled to more hospitable temperatures, the plankton prospered -- and in turn created more oxygen through photosynthesis.
“It was a double whammy,” he said. “There's really no way around it when we combine the carbon and sulfur isotope data -- oxygen levels dramatically rose during that time.”
What can this event tell us about climate change today? “Oxygen levels have been stable for the last 50 million years, but they have fluctuated over the last 500 million,” Saltzman said. “We showed that the oxygen burst in the late Cambrian happened over only two million years, so that is an indication of the sensitivity of the carbon cycle and how fast things can change.”
Global cooling may have boosted life early in the Ordovician period, but around 450 million years ago, more tectonic activity -- most likely, the rise of the Appalachian Mountains -- brought on a deadly ice age. So while most of the world's plant and animal species were born during the Ordovician period, by the end of it, more than half of them had gone extinct.
Coauthors on this study included Seth Young, a graduate student in earth sciences at Ohio State; Ben Gill, a graduate student, and Tim Lyons, professor of earth sciences, both at the University of California, Riverside; Lee Kump, professor of geosciences at Penn State University; and Bruce Runnegar, professor of paleontology at the University of California, Los Angeles.
Adapted from materials provided by Ohio State University.

Fausto Intilla

www.oloscience.com

Devastating Earthquake May Threaten Middle East's Near Future, Geologist Predicts

Source:

http://www.sciencedaily.com/releases/2007/10/071003142432.htm

Science Daily — The best seismologists in the world don’t know when the next big earthquake will hit. But a Tel Aviv University geologist suggests that earthquake patterns recorded in historical documents of Middle Eastern countries indicate that the region’s next significant quake is long overdue.

A major quake of magnitude seven on the Richter scale in the politically-fragile region of the Middle East could have dire consequences for precious holy sites and even world peace, says Tel Aviv University geologist Dr. Shmulik Marco. In light of this imminent danger, Marco, from the school’s Department of Geophysics and Planetary Sciences, has taken an historical approach to earthquake forecasting by using ancient records from the Vatican and other religious sources in his assessment. The past holds the key to the future, he says.
“All of us in the region should be worried,” explains Marco, who dedicates his career to piecing together ancient clues.
Based on the translations of hundreds of documents -- some of the originals of which he assumes reside in Vatican vaults -- Marco has helped determine that a series of devastating earthquakes have hit the Holy Land over the last two thousand years. The major ones were recorded along the Jordan Valley in the years 31 B.C.E., 363 C.E., 749 C.E., and 1033 C.E. “So roughly,” warns Marco, “we are talking about an interval of every 400 years. If we follow the patterns of nature, a major quake should be expected any time because almost a whole millennium has passed since the last strong earthquake of 1033.”
Written by monks and clergy, the documents, which span about two millenia, can help determine the location and impact of future quakes on several fault planes cutting through Israel and its neighboring countries, Marco believes. “We use the records, written in churches and monasteries or by hermits in the desert, to find patterns,” he says. Marco credits the help of an international team of historians, who have deciphered the Latin, Greek, and Arabic of the original correspondence.
He continues, “Even if these papers were not ‘officially’ recording history, they hold a lot of information. ... Some are letters to Europe asking for funding of church repairs. And while many of these accounts are told in an archaic religious manner, they help us confirm the dates and location of major calamities. Following these patterns in the past can be a good predictor of the future.”
One of the most cited Christian chroniclers in history upon whom Marco bases some of his conclusions is a ninth-century Byzantine aristocratic monk named Theophanes, venerated today by Catholics. In one manuscript, Theophanes wrote, “A great earthquake in Palestine, by the Jordan and in all of Syria on 18 January in the 4th hour. Numberless multitudes perished, churches and monasteries collapsed especially in the desert of the Holy City.”
While Christian sources helped Marco confirm ancient catastrophes and cast light on future ones, Jewish sources from the Bible also gave him small pieces of the puzzle. A verse in Zachariah (Ch. 14) describes two instances of earthquakes, one of which split apart the Mount of Olives, he says. Muslim clergy have also collected ancient correspondence, which further broadens the picture.
”Earthquakes are a manifestation of deeper processes inside the earth,” Marco says. “My questions and analysis examine how often they occur and whether there is pattern to them, temporally or spatially. I am looking for patterns and I can say that based on ancient records, the pattern in Israel around the Dead Sea region is the most disturbing to us.
“When it strikes and it will this quake will affect Amman, Jordan as well as Ramallah, Bethlehem, and Jerusalem. Earthquakes don’t care about religion or political boundaries,” Marco concludes.
Note: This story has been adapted from material provided by Tel Aviv University.

Fausto Intilla

www.oloscience.com

Carbon Dioxide Did Not End The Last Ice Age, Study Says

Source:

http://www.sciencedaily.com/releases/2007/09/070927154905.htm

Science Daily — Carbon dioxide did not cause the end of the last ice age, a new study in Science suggests, contrary to past inferences from ice core records.

"There has been this continual reference to the correspondence between CO2 and climate change as reflected in ice core records as justification for the role of CO2 in climate change," said USC geologist Lowell Stott, lead author of the study, slated for advance online publication Sept. 27 in Science Express.
"You can no longer argue that CO2 alone caused the end of the ice ages."
Deep-sea temperatures warmed about 1,300 years before the tropical surface ocean and well before the rise in atmospheric CO2, the study found. The finding suggests the rise in greenhouse gas was likely a result of warming and may have accelerated the meltdown -- but was not its main cause.
The study does not question the fact that CO2 plays a key role in climate.
"I don't want anyone to leave thinking that this is evidence that CO2 doesn't affect climate," Stott cautioned. "It does, but the important point is that CO2 is not the beginning and end of climate change."
While an increase in atmospheric CO2 and the end of the ice ages occurred at roughly the same time, scientists have debated whether CO2 caused the warming or was released later by an already warming sea.
The best estimate from other studies of when CO2 began to rise is no earlier than 18,000 years ago. Yet this study shows that the deep sea, which reflects oceanic temperature trends, started warming about 19,000 years ago.
"What this means is that a lot of energy went into the ocean long before the rise in atmospheric CO2," Stott said.
But where did this energy come from" Evidence pointed southward.
Water's salinity and temperature are properties that can be used to trace its origin -- and the warming deep water appeared to come from the Antarctic Ocean, the scientists wrote.
This water then was transported northward over 1,000 years via well-known deep-sea currents, a conclusion supported by carbon-dating evidence.
In addition, the researchers noted that deep-sea temperature increases coincided with the retreat of Antarctic sea ice, both occurring 19,000 years ago, before the northern hemisphere's ice retreat began.
Finally, Stott and colleagues found a correlation between melting Antarctic sea ice and increased springtime solar radiation over Antarctica, suggesting this might be the energy source.
As the sun pumped in heat, the warming accelerated because of sea-ice albedo feedbacks, in which retreating ice exposes ocean water that reflects less light and absorbs more heat, much like a dark T-shirt on a hot day.
In addition, the authors' model showed how changed ocean conditions may have been responsible for the release of CO2 from the ocean into the atmosphere, also accelerating the warming.
The link between the sun and ice age cycles is not new. The theory of Milankovitch cycles states that periodic changes in Earth's orbit cause increased summertime sun radiation in the northern hemisphere, which controls ice size.
However, this study suggests that the pace-keeper of ice sheet growth and retreat lies in the southern hemisphere's spring rather than the northern hemisphere's summer.
The conclusions also underscore the importance of regional climate dynamics, Stott said. "Here is an example of how a regional climate response translated into a global climate change," he explained.
Stott and colleagues arrived at their results by studying a unique sediment core from the western Pacific composed of fossilized surface-dwelling (planktonic) and bottom-dwelling (benthic) organisms.
These organisms -- foraminifera -- incorporate different isotopes of oxygen from ocean water into their calcite shells, depending on the temperature. By measuring the change in these isotopes in shells of different ages, it is possible to reconstruct how the deep and surface ocean temperatures changed through time.
If CO2 caused the warming, one would expect surface temperatures to increase before deep-sea temperatures, since the heat slowly would spread from top to bottom. Instead, carbon-dating showed that the water used by the bottom-dwelling organisms began warming about 1,300 years before the water used by surface-dwelling ones, suggesting that the warming spread bottom-up instead.
"The climate dynamic is much more complex than simply saying that CO2 rises and the temperature warms," Stott said. The complexities "have to be understood in order to appreciate how the climate system has changed in the past and how it will change in the future."
Stott's collaborators were Axel Timmermann of the University of Hawaii and Robert Thunell of the University of South Carolina. Stott was supported by the National Science Foundation and Timmerman by the International Pacific Research Center.
Stott is an expert in paleoclimatology and was a reviewer for the Intergovernmental Panel on Climate Change. He also recently co-authored a paper in Geophysical Research Letters tracing a 900-year history of monsoon variability in India.
The study, which analyzed isotopes in cave stalagmites, found correlations between recorded famines and monsoon failures, and found that some past monsoon failures appear to have lasted much longer than those that occurred during recorded history. The ongoing research is aimed at shedding light on the monsoon's poorly understood but vital role in Earth's climate.
Note: This story has been adapted from material provided by University of Southern California.

Fausto Intilla

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