A team of scientists from the NIOZ Royal Netherlands Institute for Sea Research and the University of Bremen (Germany) has determined that a major change in the climate of the Sahara and Sahel region of North Africa facilitated early human migrations from the African continent. The team's findings will be published online in the Nov. 9th installment of Early Edition of the Proceedings of the National Academy of Sciences USA. Among the key findings are that the Sahara desert and the Sahel were considerably wetter around 9,000, 50,000 and 120,000 years ago than at present, allowing for the growth of trees instead of grasses.

Dust in marine sediment cores

The researchers studied marine sediments covering nearly 200,000 years collected from the seafloor off the coast of Guinea in West Africa. Strong off-shore winds transport large volumes of dust from the Sahara and Sahel to the study area. Mixed in with the dust are plant leaf waxes, which are blown long distances across the African continent to the Atlantic Ocean, where they were ultimately deposited on the seafloor at about 3 km depth.

Over thousands of years, layers of sediment accumulated on the seafloor, each layer containing evidence of past environmental conditions in Northern Africa. The plant leaf waxes are resistant to degradation and when trapped within layers of sediment, they can be very well-preserved for millions of years.

Vegetation changes in the Sahara

Based on analysis of plant leaf waxes the researchers could determine the relative importance of trees and grasses in the Sahara and Sahel regions. Trees generally require more water to survive than do tropical grasses, and so by analysing the plant leaf waxes to determine if they were produced by trees or grasses, the scientists could examine past precipitation changes in tropical Africa over the last 200,000 years.

During three discrete periods, ca. 120,000-110,000 years, 50,000- 45,000 and 10,000-8,000 years ago, substantially more trees grew in Sahara and the Sahel, indicating significantly wetter conditions than at present. The two oldest periods exactly coincide with times when the earliest humans were migrating out of East Africa to northern Africa, the Middle East, Asia and eventually Europe. At these times, the wetter conditions in central North Africa likely enabled humans to cross this normally inhospitable region, allowing them to migrate into other continents. When climate in the Sahara and Sahel turned dry again, humans were forced out of these areas causing genetic and cultural changes in already inhabited regions such as Northern Africa and the Middle East.

Changes in ocean circulation caused a wetter Sahara

The researchers also looked for the causes of these major climate shifts to much wetter conditions in the Sahara and found that they were indirectly related to an increase in the strength of the major current system, the Atlantic Overturning Circulation (AOC). The researchers could assess the strength of this current by analysing fossilized tiny shells of small animals (benthic foraminifera).When the intensity of the AOC changes, this leads to changes in the chemical composition of the deep water masses, which is then reflected in the shells ofbenthic foraminifera. The researchers found that when the AOC weakened, more grasses were present in central North Africa indicating a drier climate. Likely, the weakening of the AOC was caused by increased freshwater input to the high-latitudes, leading to less saline surface waters. This freshwater input also caused surface cooling in these regions, in turn leading to movement of cold air from the high-latitudes to the tropics, and causing drier conditions in central North Africa.

Thus, early human migrations from the African continent were likely triggered by events originating far away in the North Atlantic.

This research project was funded by the Netherlands Organisation for Scientific Research (NWO) and the Deutsche Forschungsgemeinschaft Research Centre/Excellence Cluster "The Ocean in the Earth System".

In the film The Day After Tomorrow, the world enters the icy grip of a new glacial period within the space of just a few weeks. Now new research shows that this scenario may not be so far from the truth after all.

William Patterson, from the University of Saskatchewan in Canada, and his colleagues have shown that switching off the North Atlantic circulation can force the Northern hemisphere into a mini 'ice age' in a matter of months. Previous work has indicated that this process would take tens of years.

Around 12,800 years ago the northern hemisphere was hit by a mini ice-age, known by scientists as the Younger Dryas, and nicknamed the 'Big Freeze', which lasted around 1300 years. Geological evidence shows that the Big Freeze was brought about by a sudden influx of freshwater, when the glacial Lake Agassiz in North America burst its banks and poured into the North Atlantic and Arctic Oceans. This vast pulse, a greater volume than all of North America's Great Lakes combined, diluted the North Atlantic conveyor belt and brought it to a halt.

Without the warming influence of this ocean circulation temperatures across the Northern hemisphere plummeted, ice sheets grew and human civilisation fell apart.

Previous evidence from Greenland ice cores has indicated that this sudden change in climate occurred over the space of a decade or so. Now new data shows that the change was amazingly abrupt, taking place over the course of a few months, or a year or two at most.

Patterson and his colleagues have created the highest resolution record of the 'Big Freeze' event to date, from a mud core taken from an ancient lake, Lough Monreach, in Ireland. Using a scalpel layers were sliced from the core, just 0.5mm thick, representing a time period of one to three months.

Carbon isotopes in each slice reveal how productive the lake was, while oxygen isotopes give a picture of temperature and rainfall. At the start of the 'Big Freeze' their new record shows that temperatures plummeted and lake productivity stopped over the course of just a few years. "It would be like taking Ireland today and moving it up to Svalbard, creating icy conditions in a very short period of time," says Patterson, who presented the findings at the European Science Foundation BOREAS conference on humans in the Arctic, in Rovaniemi, Finland.

Meanwhile, their isotope record from the end of the Big Freeze shows that it took around two centuries for the lake and climate to recover, rather than the abrupt decade or so that ice cores indicate. "This makes sense because it would take time for the ocean and atmospheric circulation to turn on again," says Patterson.

Looking ahead to the future Patterson says there is no reason why a 'Big Freeze' shouldn't happen again. "If the Greenland ice sheet melted suddenly it would be catastrophic," he says.

This study was part of a broad network of 38 individual research teams from Europe, Russia, Canada and the USA forming the European Science Foundation EUROCORES programme 'Histories from the North -- environments, movements, narratives' (BOREAS). This highly interdisciplinary initiative brought together scientists from a wide range of disciplines including humanities, social, medical, environmental and climate sciences.

Which come first, the supermassive black holes that frantically devour matter or the enormous galaxies where they reside? A brand new scenario has emerged from a recent set of outstanding observations of a black hole without a home: black holes may be "building" their own host galaxy. This could be the long-sought missing link to understanding why the masses of black holes are larger in galaxies that contain more stars.

"The 'chicken and egg' question of whether a galaxy or its black hole comes first is one of the most debated subjects in astrophysics today," says lead author David Elbaz. "Our study suggests that supermassive black holes can trigger the formation of stars, thus 'building' their own host galaxies. This link could also explain why galaxies hosting larger black holes have more stars."

To reach such an extraordinary conclusion, the team of astronomers conducted extensive observations of a peculiar object, the nearby quasar HE0450-2958 (see ESO PR 23/05 for a previous study of this object), which is the only one for which a host galaxy has not yet been detected [1]. HE0450-2958 is located some 5 billion light-years away.

Until now, it was speculated that the quasar's host galaxy was hidden behind large amounts of dust, and so the astronomers used a mid-infrared instrument on ESO's Very Large Telescope for the observations [2]. At such wavelengths, dust clouds shine very brightly, and are readily detected. "Observing at these wavelengths would allow us to trace dust that might hide the host galaxy," says Knud Jahnke, who led the observations performed at the VLT. "However, we did not find any. Instead we discovered that an apparently unrelated galaxy in the quasar's immediate neighbourhood is producing stars at a frantic rate."

These observations have provided a surprising new take on the system. While no trace of stars is revealed around the black hole, its companion galaxy is extremely rich in bright and very young stars. It is forming stars at a rate equivalent to about 350 Suns per year, one hundred times more than rates for typical galaxies in the local Universe.

Earlier observations had shown that the companion galaxy is, in fact, under fire: the quasar is spewing a jet of highly energetic particles towards its companion, accompanied by a stream of fast-moving gas. The injection of matter and energy into the galaxy indicates that the quasar itself might be inducing the formation of stars and thereby creating its own host galaxy; in such a scenario, galaxies would have evolved from clouds of gas hit by the energetic jets emerging from quasars.

"The two objects are bound to merge in the future: the quasar is moving at a speed of only a few tens of thousands of km/h with respect to the companion galaxy and their separation is only about 22 000 light-years," says Elbaz. "Although the quasar is still 'naked', it will eventually be 'dressed' when it merges with its star-rich companion. It will then finally reside inside a host galaxy like all other quasars."

Hence, the team have identified black hole jets as a possible driver of galaxy formation, which may also represent the long-sought missing link to understanding why the mass of black holes is larger in galaxies that contain more stars [3].

"A natural extension of our work is to search for similar objects in other systems," says Jahnke.

Future instruments, such as the Atacama Large Millimeter/submillimeter Array, the European Extremely Large Telescope and the NASA/ESA/CSA James Webb Space Telescope will be able to search for such objects at even larger distances from us, probing the connection between black holes and the formation of galaxies in the more distant Universe.

Notes

[1] Supermassive black holes are found in the cores of most large galaxies; unlike the inactive and starving one sitting at the centre of the Milky Way, a fraction of them are said to be active, as they eat up enormous amounts of material. These frantic actions produce a copious release of energy across the whole electromagnetic spectrum; particularly spectacular is the case of quasars, where the active core is so overwhelmingly bright that it outshines the luminosity of the host galaxy.

[2] This part of the study is based on observations performed at mid-infrared wavelengths, with the powerful VLT spectrometer and imager for the mid-infrared (VISIR) instrument at the VLT, combined with additional data including: spectra acquired using VLT-FORS, optical and infrared images from the NASA/ESA Hubble Space Telescope, and radio observations from the Australia Telescope National Facility.

[3] Most galaxies in the local Universe contain a supermassive black hole with a mass about 1/700th the mass of the stellar bulge. The origin of this black hole mass versus stellar mass relation is one of the most debated subjects in modern astrophysics.

Amphibians, for years considered a leading indicator of environmental degradation, are not uniquely susceptible to pollution, according to a meta-analysis to be published in Ecology Letters.

After a review of over 28,000 toxicological tests, researchers from the University of South Dakota, Yale University and Washington State University are challenging the prevailing view that amphibians, with their permeable skin and aquatic environment, are particularly sensitive to environmental threats and, as such, are "canaries," or predictors of environmental decline.

"The very simple message is that for most of the classes of chemical compounds we looked at, frogs range from being moderately susceptible to being bullet-proof," said David Skelly, professor of ecology at the Yale School of Forestry & Environmental Studies and a member of the research team. "There are lots of other kinds of environmental threats that have led to their decline, including habitat conversion, harvesting for food and the global spread of the Chytrid fungus, which is mowing down these species in its path."

The team, led by Jacob Kerby, an assistant professor at the University of South Dakota, based its analysis on information gleaned from the Environmental Protection Agency's (EPA) Aquatic Toxicity Information Retrieval database, examining 1,279 species, among them segmented worms, fish, bivalves such as clams, insects and snails. Those species were exposed in water to various concentrations of 107 chemical agents, including inorganic chemicals, pesticides, heavy metals and phenols, a class of chemical compound.

"What our results suggest is that all animals are susceptible to chemical stressors and that amphibians are potentially good indicators," said Kerby. "There isn't any evidence that they're a uniquely leading indicator. We tried to be comprehensive in the types of chemicals and organisms that we examined."

In light of the findings, Skelly said, scientists should evaluate the absence, presence or abundance of amphibians in wild populations as "signals" of potential exposure to different chemicals in the environment. "If we have such an understanding for several species, we may be able to use their responses, collectively, as a means of narrowing potential causes of environmental degradation," he said.

The EPA, according to the paper, uses African Clawed Frogs as a proxy for biological diversity when determining a species' sensitivity to chemical exposures, even though that particular species does not occur naturally in North America. "Our knowledge of amphibians' sensitivity to particular chemicals or classes of chemicals has not been used to design assays for effects in nature," Skelly said.

Scientists at the European Organisation for Nuclear Research (CERN) hope experiments will already start giving clues about the origins of the universe in the coming months as the world's biggest particle collider starts moving to full power.

"It's a great achievement to have come this far in so short a time," said CERN Director General Rolf Heuer about the collision, achieved by sending two bunches of subatomic particles around the ring in opposite directions.

It is only three days since the "Big Bang Machine," or Large Hadron Collider (LHC), was switched back on after being halted by an accident 14 months ago, just 10 days after its first start-up.

Earlier, physicist Steve Myers told Reuters it could take until 2011 for beams of protons to hit top velocity in the nearly $10 billion experiment, which involves scientists from dozens of countries.

The key aim of the project at the CERN research center is to try to discover how the universe took shape, after the Big Bang 13.7 billion years ago spilled out matter at vast speeds and energies that eventually became suns, stars, planets and then life itself.

Experiments in a previous collider at the CERN research center near Geneva at the foot of the French Jura mountains staged particle collisions producing energy very close to that of the Big Bang.

The LHC operating at its full might should recreate conditions like those just one billionth of a second after the primeval explosion.

The scientists now plan to increase the beam intensity and accelerate the beams further so they can gather enough collision data by Christmas to help set up experiments.

In geology as in cancer research, the silver bullet theory always gets the headlines and nearly always turns out to be wrong. For geologists who study mass extinctions, the silver bullet is a giant asteroid plunging to earth

But an asteroid is the prime suspect only in the most recent of five mass extinctions, said USC earth scientist David Bottjer. The cataclysm 65 million years ago wiped out the dinosaurs.

"The other four have not been resolvable to a rock falling out of the sky," Bottjer said.

For example, Bottjer and many others have published studies suggesting that the end-Permian extinction 250 million years ago happened in essence because "the earth got sick."

The latest research from Bottjer's group suggests a similar slow dying during the extinction 200 million years ago at the boundary of the Triassic and Jurassic eras.

At the 2008 Joint Annual Meeting of the Geological Society of America, USC doctoral student Sarah Greene drew similarities between ocean conditions at the Triassic-Jurassic boundary and after the end-Permian extinction.

At both those times, bouquet-like structures of aragonite crystals formed on the ocean floor. Such structures are extremely rare in Earth's history, Greene said.

"The fact that these deposits have only been found at these two specific times that are associated with mass extinction suggests at the very least that maybe there's some shared ocean geochemistry … that could be related to the cause of the extinctions," Greene said.

"The Triassic-Jurassic extinction cause is totally up for grabs at the moment," she added.

Also at the meeting, USC doctoral student Rowan Martindale presented results from her studies of coral reefs during the Triassic-Jurassic extinction.

"The coral reefs look actually very similar to modern coral reefs," she said. "At the end-Triassic mass extinction, you lose all your reef systems. And nobody's figured out why that is."

Martindale identified two distinct types of ancient reefs: one dominated by coral and another consisting mainly of mud and debris, possibly held together by bacteria.

A theory for the end-Triassic extinction needs to explain how both types of reefs could have been killed off, Martindale said.

Any knowledge about end-Triassic reef death could be useful in understanding the current reef crisis, widely attributed to climate change.

"We're looking at it as a model to give us any insight that we might have for today's decline for coral reefs," Bottjer said.

The Joint Annual Meeting was held Oct. 5-9 in Houston. It was the first joint meeting of the Geological Society of America, the Soil Science Society of America, the American Society of Agronomy, the Crop Science Society of America and the Gulf Coast Association of Geological Societies.

Hammerhead sharks are some of the Ocean's most distinctive residents. "Everyone wants to understand why they have this strange head shape," says Michelle McComb from Florida Atlantic University. One possible reason is the shark's vision.

"Perhaps their visual field has been enhanced by their weird head shape," says McComb, giving the sharks excellent stereovision and depth perception.

However, according to McComb, there were two schools of thought on this theory. In 1942, G. Walls speculated that the sharks couldn't possibly have binocular vision because their eyes were stuck out on the sides of their heads. However, in 1984, Leonard Campagno suggested that the sharks would have excellent depth perception because their eyes are so widely separated. "In fact one of the things they say on TV shows is that hammerheads have better vision than other sharks," says McComb, "but no one had ever tested this."

Teaming up with Stephen Kajiura and Timothy Tricas, the trio decided to find out how wide a hammerhead's field of view is and whether they could have binocular vision and publish their results on November 27 2009 in the Journal of Experimental Biology.

Hammerheads come in all shapes and sizes so McComb and Kajiura, opted to work with species with heads ranging from the narrowest to the widest. Fishing for juvenile scalloped hammerheads off Hawaii and bonnethead sharks in the waters around Florida, the team successfully landed the fish and quickly transported them back to local labs to test the fish's eyesight.

The team tested the field of view in each shark's eyes by sweeping a weak light in horizontal and vertical arcs around each eye and recorded the eye's electrical activity. Comparing the hammerheads with pointy nosed species, the team found that the scalloped hammerheads had the largest monocular visual field, at an amazing 182 deg., and the bonnethead had a 176 deg. visual field, which was bigger than that of the pointy nosed blacknose and lemon sharks, at 172 deg. and 159 deg., respectively.

Having collected the animals' monocular visual fields, the team plotted the visual fields of both eyes on a chart of each fish's head to see whether they overlapped. Amazingly, they did. The scalloped hammerhead had a massive binocular overlap of 32 deg. in front of their heads (three times the overlap in the pointy nosed species) while the bonnet head had a respectable 13 deg. overlap. And when the team measured the binocular overlap of the shark with the widest hammerhead, the winghead shark, it was a colossal 48 deg. The hammerheads' wide heads certainly improved their binocular vision and depth perception.

Finally, the team factored in the sharks' eye and head movements and found that the forward binocular overlaps rocketed to an impressive 69 deg. for the scalloped hammerheads and 52 deg. for the bonnetheads. Even more surprisingly, the team realised that the bonnethead and scalloped hammerheads have an excellent stereo rear-view: they have a full 360 deg. view of the world.

"When we first started the project we didn't think that the hammerhead would have binocular vision at all. We thought no way; we were out there to dispel the myth," says McComb. But despite their preconceptions, the team have shown that the sharks not only have outstanding forward stereovision and depth perception, but a respectable stereo rear view too, which is even better than the TV shows would have us believe

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After the End-Permian extinction 252.6 million years ago, ammonoids diversified and recovered 10 to 30 times faster than previous estimates. The surprising discovery raises questions about paleontologists' understanding of the dynamics of evolution of species and the functioning of the biosphere after a mass extinction.

The study, conducted by a Franco-Swiss collaboration involving the laboratories Biogéosciences (Université de Bourgogne / CNRS), Paléoenvironnements & Paléobiosphère (Université Claude Bernard / CNRS) and the Universities of Zurich and Lausanne (Switzerland), appears in the August 28 issue of Science.

The history of life on Earth has been punctuated by a number of mass extinctions, brief periods of extreme loss of biodiversity. These extinctions are followed by phases during which surviving species recover and diversify. The End-Permian extinction, which took place between the Permian (299 – 252.6 MY) and Triassic (252.6 – 201.6 MY), is the greatest mass extinction on record, resulting in the loss of 90% of existing species. It is associated with intensive volcanic activity in China and Siberia. It marks the boundary between the Paleozoic and Mesozoic Eras. Until now, studies had shown that the biosphere took between 10 and 30 million years to recover the levels of biodiversity seen before the extinction.

Ammonoids are cephalopod swimmers related the nautilus and squid. They had a shell, and disappeared from the oceans at the same time as the dinosaurs, 65 million years ago, after being a major part of marine fauna for 400 MY.

The Franco-Swiss team of paleontologists has shown that ammonoids needed only one million years after the End-Permian extinction to diversify to the same levels as before. The cephalopods, which were abundant during the Permian, narrowly missed being eradicated during the extinction: only two or three species survived and a single species seems to have been the basis for the extraordinary diversification of the group after the extinction. It took researchers seven years to gather new fossils and analyze databases in order to determine the rate of diversification of the ammonoids. In all, 860 genera from 77 regions around the world were recorded at 25 successive time intervals from the Late Carboniferous to the Late Triassic, a period of over 100 million years.

The discovery of this explosive growth over a million years takes a heated debate in a new direction. Indeed, it suggests that earlier estimates for the End-Permian extinction were based on truncated data and imprecise or incorrect dating. Furthermore, the duration for estimated recovery after other lesser extinctions all vary between 5 and 15 million years.

The result obtained here suggests that these estimates should probably be revised downwards. The biosphere is most likely headed towards a sixth mass extinction, and this discovery reminds us that the recovery of existing species after an extinction is a very long process, taking several tens of thousands of human generations at the very least

Years of scientific debate over the extinction of ancient species in North America have yielded many theories. However, new findings from J. Tyler Faith, GW Ph.D. candidate in the hominid paleobiology doctoral program, and Todd Surovell, associate professor of anthropology at the University of Wyoming, reveal that a mass extinction occurred in a geological instant.

During the late Pleistocene, 40,000 to 10,000 years ago, North America lost over 50 percent of its large mammal species. These species include mammoths, mastodons, giant ground sloths, among many others. In total, 35 different genera (groups of species) disappeared, all of different habitat preferences and feeding habits.

What event or factor could cause such a mass extinction? The many hypotheses that have been developed over the years include: abrupt change in climate, the result of comet impact, human overkill and disease. Some researchers believe that it may be a combination of these factors, one of them, or none.

A particular issue that has also contributed to this debate focuses on the chronology of extinctions. The existing fossil record is incomplete, making it more difficult to tell whether or not the extinctions occurred in a gradual process, or took place as a synchronous event. In addition, it was previously unclear whether species are missing from the terminal Pleistocene because they had already gone extinct or because they simply have not been found yet.

However, new findings from Faith indicate that the extinction is best characterized as a sudden event that took place between 13.8 and 11.4 thousand years ago. Faith's findings support the idea that this mass extinction was due to human overkill, comet impact or other rapid events rather than a slow attrition.

"The massive extinction coincides precisely with human arrival on the continent, abrupt climate change, and a possible extraterrestrial impact event" said Faith. "It remains possible that any one of these or all, contributed to the sudden extinctions. We now have a better understanding of when the extinctions took place and the next step is to figure out why."

When small earthquakes shake the central U.S., citizens often fear the rumbles are signs a big earthquake is coming. Fortunately, new research instead shows that most of these earthquakes are aftershocks of big earthquakes (magnitude 7) in the New Madrid seismic zone that struck the Midwest almost 200 years ago.

The study, conducted by researchers from Northwestern University and the University of Missouri-Columbia, will be published in the Nov. 5 issue of the journal Nature.

"This sounds strange at first," said the study's lead author, Seth Stein, the William Deering Professor of Geological Sciences in the Weinberg College of Arts and Sciences at Northwestern. "On the San Andreas fault in California, aftershocks only continue for about 10 years. But in the middle of a continent, they go on much longer."

There is a good reason, explains co-investigator Mian Liu, professor of geological sciences at Missouri. "Aftershocks happen after a big earthquake because the movement on the fault changed the forces in the earth that act on the fault itself and nearby. Aftershocks go on until the fault recovers, which takes much longer in the middle of a continent."

The difference, Stein explains, is that the two sides of the San Andreas fault move past each other at a speed of about one and a half inches in a year -- which is fast on a geologic time scale. This motion "reloads" the fault by swamping the small changes caused by the last big earthquake, so aftershocks are suppressed after about 10 years. The New Madrid faults, however, move more than 100 times more slowly, so it takes hundreds of years to swamp the effects of a big earthquake.

"A number of us had suspected this," Liu said, "because many of the earthquakes we see today in the Midwest have patterns that look like aftershocks. They happen on the faults we think caused the big earthquakes in 1811 and 1812, and they've been getting smaller with time."

To test this idea, Stein and Liu used results from lab experiments on how faults in rocks work to predict that aftershocks would extend much longer on slower moving faults. They then looked at data from faults around the world and found the expected pattern. For example, aftershocks continue today from the magnitude 7.2 Hebgen Lake earthquake that shook Montana, Idaho and Wyoming 50 years ago.

"This makes sense because the Hebgen Lake fault moves faster than the New Madrid faults but slower than the San Andreas," Stein noted. "The observations and theory came together the way we like but don't always get."

Aftershocks go on for long times in other places inside continents, Stein said. It even looks like we see small earthquakes today in the area along Canada's Saint Lawrence valley where a large earthquake occurred in 1663.

The new results will help investigators in both understanding earthquakes in continents and trying to assess earthquake hazards there. "Until now," Liu observed, "we've mostly tried to tell where large earthquakes will happen by looking at where small ones do." That's why many scientists were surprised by the disastrous May 2008 magnitude 7.9 earthquake in Sichuan, China -- a place where there hadn't been many earthquakes in the past few hundred years.

"Predicting big quakes based on small quakes is like the 'Whack-a-mole' game -- you wait for the mole to come up where it went down," Stein said. "But we now know the big earthquakes can pop up somewhere else. Instead of just focusing on where small earthquakes happen, we need to use methods like GPS satellites and computer modeling to look for places where the earth is storing up energy for a large future earthquake. We don't see that in the Midwest today, but we want to keep looking."

Deep under the sea, a fossil the size of a sand grain is nestled among a billion of its closest dead relatives. Known as foraminifera, these complex little shells of calcium carbonate can tell you the sea level, temperature, and ocean conditions of Earth millions of years ago. That is, if you know what to look for.

Assistant Professor of Earth and Environmental Sciences at Rensselaer Polytechnic Institute Miriam Katz has spent the past two decades studying these ancient, deep-sea fossils to reconstruct the climates of Earth up to 250 million years ago. Through ice ages and greenhouse climates, Katz has been able to piece together oxygen, carbon, and faunal data to paint a portrait of how, when, and why our climate has changed so drastically over geologic history. In addition, her investigations into the deep past of Earth have important implications for understanding and tracking the potential drastic repercussions of modern, human-induced climate change.

"There is a saying among scientists in my field that 'the past is a window on the future,' " Katz said. "By reconstructing the climates of the past, particularly those where we see massive and rapid changes in the climate, we can provide a science-based means to explore or predict possible system responses to the current climate change."

While her work requires a lot of time in the laboratory, Katz has spent nearly two years at sea on seven different ocean voyages around the world to drill for foraminifera as part of the Integrated Ocean Drilling Program (IODP), an international marine research effort that explores the Earth's history and structure by looking at seafloor sediments and rocks. During each two-month IODP excursion, Katz and the other scientists on board never set foot on land and spend hours poking through the millions of layers of sediment, trapped gases, fossils, and trace elements found in huge cores drilled from deep under the seafloor.

Just a few inches in diameter, each core is painstakingly drilled and removed from the seafloor. From top to bottom, the core provides a reverse chronology of the various organisms, sediments, and elements that were found on Earth throughout history. Unlike cores from sedimentary layers from the continents that are quickly destroyed by the forces of plate tectonics, wind, and water, these rarely disturbed ocean sediment cores can provide records up to 180 million years ago as new layers of sediment bury and preserve those of the past.

Katz is most interested in the foraminifera found in the cores. The foraminifera she studies live on or just below the seafloor. When they die, their hard shells are incorporated in the surrounding sediments and buried over time in a nearly uniform layer.

The assemblages of foraminifera in each layer can provide valuable information on the climate of that time. "Some species are only found in certain environments, such as in warm water or in shallow, tidal areas," Katz said. "By piecing together the species assemblages that are found in a given area during the given time period, we can reconstruct the sea level and ocean and climate conditions of that period based on our knowledge of each foraminiferal species."

In addition to the specific type of foraminifera seen in each layer, valuable information can also be gathered by looking at variations in the chemical structure of the fossilized calcium carbonate (CaCO3) shell seen in the various layers. During their life, the foraminiferal shells are formed from the elements found in the seas that they lived in. The ratios of various isotopes of the elements carbon and oxygen found in foraminiferal shells at different times in Earth's history provide important information needed to reconstruct the climate and ocean waters that surrounded them during their short lives millions of years ago.

In the case of oxygen (O), the ratio between isotopes 18O and 16O tells scientists how much water is trapped in glacial ice, providing important clues about temperature and the size of the ancient continental ice sheets. Carbon (C) in the shells can be analyzed for either 12C or 13C isotopes. Plants prefer to incorporate lighter 12C during photosynthesis, increasing the ratio of 13C to 12C in foraminifera when plant and algae production is high. This carbon data provides clues on the types and amounts of vegetation at various times as well as ocean circulation, according to Katz.

Gathering this information from cores has allowed Katz to develop important theories on one of the most recent and dramatic climate change events that has occurred in recent geologic history -- the transition from the greenhouse climate of the Eocene epoch to the "icehouse" or glacial conditions of the Oligocene epoch approximately 33.5 million years ago.

"The boundary between the late Eocene to the early Oligocene is a striking example of rapid climate change that we can look to in Earth's past," Katz said. "Information from this period can provide us with important information on how rapid changes in temperature can significantly impact ice volume, sea level, and the evolution of life on Earth."

Katz has used oxygen and carbon isotopes as well as the ratio of magnesium to calcium within foraminifera from this period to reconstruct the changes that occurred as the climate rapidly cooled. Along with her research colleagues, she has shown that ice sheets at the end of the transition were approximately 25 percent larger than today, causing a decrease in sea level of approximately 105 meters.

Her research also reaches even further back to reconstruct conditions earlier in Earth's history. In particular, she took part in a study of atmospheric oxygen and carbon dioxide concentrations since the Jurassic period 205 million years ago. The group has found that oxygen levels doubled in the short period of time from the Jurassic period to the Eocene epoch (~150 million years ago), providing a climate with just enough oxygen for placental mammals to develop.

Spanish researchers have studied the fossil record of hadrosaurs, the so-called 'duck-billed' dinosaurs, in the Iberian Peninsula for the purpose of determining that they were the last of their kind to inhabit the European continent before disappearing during the K/T extinction event that occurred 65.5 million years ago. Most notable among these fossils is the discovery of a new hadrosaur, the Arenysaurus ardevoli, found in Huesca, Spain.

A few million years before the catastrophic event that led to the extinction of dinosaurs (with the exception of birds), several species of hadrosaurs coexisted in the Iberian Peninsula. This is what a Spanish team of paleontologists have demonstrated in a research article published in the Journal of Vertebrate Paleontology.

"The Iberian archeological record is important from an European context due to the quantity and quality of the fossil material discovered," explains Xavier Pereda-Suberbiola, one of the study's authors and a researcher at the University of the Basque Country (UPV / EHU).

The researcher, collaborating with paleontologists from the University of Zaragoza, Valencia, Complutense of Madrid, Autonoma de Barcelona and the Jurassic Museum of Asturias, specifies that the presence of evolved hadrosaurs in Europe could be due to migration from Asia and North America.

"In Europe, primitive hadrosaurs coexist with evolved hadrosaurs, and the persistence of basal members could be due to the insular palaeobiogeography of Europe during the Upper Cretaceous," states the scientist. In addition to the fossils found in the Iberian Peninsula, hadrosaur fossils have been found in the Netherlands, which date back to Late Cretaceous, "although the material is more fragmented than those found in Huesca and Lleida," adds Pereda-Suberbiola.

During that time period, Europe was isolated from other continents and this may have led to the survival of certain lineages. "The European hadrosaur faunas are different from those seen in North America and Asia, which are both dominated by evolved species," explains Pereda-Suberbiola.

Next to the hadrosaurs, identifiable by the fossilized mandibles found in the arechological sites of La Solana (Valencia) and Fontllonga (Lleida), were a lambeosaurine hadrosaurs yet to be defined, and a newly discovered lambeosaurine, the Arenysaurus ardevoli.

An articulated cranium of great value

The study of the last hadrosaurs that lived in the Iberian Peninsula has been possible thanks to the discovery by the Aragosaurus-IUCA Group of the University of Zaragoza, led by Jose Ignacio Canudo, of the first articulated hadrosaur skull found in southern Europe, from the archeological sites of Arén, in Huesca, Spain.

The skull belongs to an Arenysaurus ardevoli, a lambeosaurine (hadrosaur with a hollow cranial crest), whose description was recently published in the French journal Comptes Rendus Palevol, and was part of the Spanish fossil record.

According to paleontologists, the new lambeosaurine lived between 65.5 and 68 million years ago, had a very prominent frontal dome, and its biogeographical relationships suggest a paleobiogeographical connection between Asia and Europe during the Late Cretaceous.

Researchers have found, in addition to the partially articulated skull, the mandibular remains and postcranial elements such as vertebrae, girdle and limb bones.

The Spanish archaeological record of hadrosaurs is the largest in Europe. Out of the 50 locations where dinosaur remains were discovered since 1984, nearly half have been found in Lleida and Huesca. These archeological sites stand out for containing fossils pertaining to several species of duck-billed dinosaurs.

North Carolina State University astrophysicists have answered a long-standing question about the nature of one of our galaxy’s most famous supernova explosions, discovering a new class of supernova in the process.

Dr. Stephen Reynolds, astrophysicist in NC State’s College of Physical and Mathematical Sciences, along with colleague Dr. Kazik Borkowski and a team of scientists from NASA, Rutgers University, and the Naval Research Laboratories, set out to determine whether the Kepler supernova, which occurred in 1604 A.D., was a core collapse supernova or a thermonuclear supernova.

They revealed their results in a press conference today at the annual meeting of the American Astronomical Society.

A core collapse supernova occurs when a single, massive star (with a mass eight times greater – or more – than that of our sun) reaches the end of its life and explodes. Core collapse supernovae leave pulsars, rapidly spinning neutron stars, behind when they occur. They also tend to be surrounded by circumstellar medium – leftover elements from the star that collapsed, as well as large amounts of oxygen and small amounts of iron. These supernovae are usually located near “star-forming” sites along a galaxy’s edge.

Thermonuclear, or Type Ia, supernovae occur when a white dwarf star, which typically travels through space with a companion star that eventually “leaks” its own mass onto the dwarf, reaches its mass limit and explodes. These supernovae can be found all over a galaxy, are typically not associated with any circumstellar medium, and produce large amounts of iron.

The Kepler supernova has long puzzled scientists because it has features that are common to both types of supernova: The Kepler supernova’s location and the presence of a lot of iron are indicative of a Type Ia supernova, but the dense surroundings and nitrogen-enriched circumstellar medium are commonly associated with the aftermath of a core collapse.

Reynolds and his team used the powerful Chandra X-ray telescope to observe the Kepler supernova, and they discovered that Kepler is something entirely new: a Type Ia supernova in which the progenitor of the white dwarf star that created it had enough mass to create circumstellar medium.

“We really don’t know much about Type Ia supernovae, and they’re really important to our understanding of the universe,” Reynolds says. “We use the fact that they all have similar luminosities, or brightness, to calculate the distance of galaxies and to determine how much and how quickly the universe is expanding.

“Type Ia’s are also the source of the majority of iron in the universe, and can give us a lot of information about its chemical history. A new class of Type Ia supernova will have huge implications for our ability to understand the source of the elements that create our universe.”

In just the past six weeks, two supernovae have flared up in an obscure galaxy in the constellation Hercules. Never before have astronomers observed two of these powerful stellar explosions occurring in the same galaxy so close together in time.

The galaxy, known as MCG +05-43-16, is 380 million light-years from Earth. Until this year, astronomers had never sighted a supernova popping off in this stellar congregation. A supernova is an extremely energetic and life-ending explosion of a star.

Making the event even more unusual is the fact that the two supernovae belong to different types. Supernova 2007ck is a Type II event – which is triggered when the core of a massive star runs out of nuclear fuel and collapses gravitationally, producing a shock wave that blows the star to smithereens. Supernova 2007ck was first observed on May 19.

In contrast, Supernova 2007co is a Type Ia event, which occurs when a white dwarf star accretes so much material from a binary companion star that it blows up like a giant thermonuclear bomb. It was discovered on June 4, 2007. A white dwarf is the exposed core of a star after it has ejected its atmosphere; it’s approximately the size of Earth but with the mass of our Sun.

"Most galaxies have a supernova every 25 to 100 years, so it’s remarkable to have a galaxy with two supernovae discovered just 16 days apart," says Stefan Immler of NASA’s Goddard Space Flight Center. In 2006 Immler used NASA’s Swift satellite to image two supernovae in the elliptical galaxy NGC 1316, but both of those explosions were Type Ia events, and they were discovered six months apart.

The simultaneous appearance of two supernovae in one galaxy is an extremely rare occurrence, but it’s merely a coincidence and does not imply anything unusual about MCG +05-43-16. Because the two supernovae are tens of thousands of light-years from each other, and because light travels at a finite speed, astronomers in the galaxy itself, or in a different galaxy, might record the two supernovae exploding thousands of years apart.

An unusual supernova rediscovered in seven-year-old data may be the first example of a new type of exploding star, possibly from a binary star system where helium flows from one white dwarf onto another and detonates in a thermonuclear explosion.

In a paper first published online Nov. 5 in the journal Science Express, University of California, Berkeley, and Lawrence Berkeley National Laboratory (LBNL) astronomer Dovi Poznanski and his colleagues describe the outburst, dubbed SN 2002bj, and why they believe it is a new type of explosion.

"This is the fastest evolving supernova we have ever seen," said Poznanski, a UC Berkeley post-doctoral fellow who recently joined LBNL's Computational Cosmology Center. "It was three to four times faster than a standard supernova, basically disappearing within 20 days. Its brightness just dropped like a rock."

This rapid drop, coupled with the supernova's faintness, the strong signature of helium in the spectrum of the explosion, the absence of hydrogen, and the possible presence of vanadium -- an element never previously identified in supernova spectra -- points toward helium detonation on a white dwarf, the astronomers said.

"We think this may well be a new physical explosion mechanism, not just a minor variation of ones already known," said co-author Alex Filippenko, UC Berkeley professor of astronomy. "This supernova is qualitatively different from the complete disruption of a white dwarf, known as a Type Ia supernova, or the collapse of an iron core and rebound of the surrounding material, so-called 'core-collapse supernovae.'"

Co-author Joshua Bloom, UC Berkeley associate professor of astronomy, also views SN 2002bj as a "new beast" quite different from the two well-known classes of supernovae.

"We have seen great diversity in those two main supernova mechanisms, but even within that diversity, observationally, there is a limited range of variation spectrally and in how events evolve in time," he said. "This object (SN 2002bj) falls outside that range."

The supernova was detected in 2002 in the galaxy NGC 1821, in the constellation Lepus, by Filippenko's Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory near San Jose as well as by amateur astronomers. Due to an unfortunate alignment of circumstances, the supernova was erroneously classified by the astronomical community as a common Type II supernova and filed away.

In June, Poznanski happened upon the spectrum while searching for Type II supernovae he hopes to use as distance indicators to confirm the accelerating expansion of the universe. When he carefully examined a high-quality spectrum of SN 2002bj, he realized that the supernova was not a Type II at all, but an unusual kind of supernova more akin to a Type Ia.

The spectrum had been obtained seven days after its discovery by Filippenko and Douglas Leonard, at the time a UC Berkeley graduate student, now an assistant professor of astronomy at San Diego State University, using the Keck I telescope.

"Its classification was a mistake, which is understandable given the conditions of the data. But, of course, a redress of old data with fresh eyes is not usually this fruitful," Leonard said.

Pulling out follow-up images made by KAIT, Poznanski and UC Berkeley graduate student Mohan Ganeshalingam found that the brightness of SN 2002bj dropped off so rapidly that the supernova disappeared 20 days after its discovery. An image of that area of the sky taken seven days prior to its discovery showed no supernova, so it had brightened and dimmed into obscurity in less than 27 days, whereas most supernovae brighten and dim over three to four months.

Searching through thousands of supernovae spectra, Poznanski and graduate student Ryan Chornock -- now a post-doctoral fellow at Harvard University -- could find none that had such an awkward composition, but they did come across a theory of fast but faint supernovae that seemed to fit.

Proposed by Lars Bildsten and colleagues -- Bildsten is a professor of physics at the Kavli Institute for Theoretical Physics at UC Santa Barbara -- the theory involves AM Canum Venaticorum (AM CVn) binary systems, which are composed of two white dwarfs, one of which is primarily made of helium that is being slowly pulled by gravity onto its companion. White dwarfs are the remnants of stars that burned their hydrogen down to carbon and oxygen or, in some particular cases, to helium.

In a 2007 Astrophysical Journal Letters paper, Bildsten and colleagues proposed that in AM CVn systems, when enough helium has been accumulated on the surface of the primary white dwarf, an explosion will occur that can "power a faint … and rapidly rising (few days) thermonuclear supernova."

Christopher Stubbs, chair of the Department of Physics at Harvard University, jokingly dubbed it a ''.Ia'' (point one A) supernova, because it is one-tenth as bright for one-tenth the time as a Type Ia supernova, and the name stuck.

Filippenko noted that this explosion is nothing like a regular Type Ia explosion because the white dwarf survives the detonation of the helium shell. In fact, it has similarities to both a nova and a supernova. Novas occur when matter -- primarily hydrogen -- falls onto a star and accumulates in a shell that can flare up as brief thermonuclear explosions. SN 2002bj is a "super" nova, generating about 1,000 times the energy of a standard nova, he said.

The explosion would have created heavy elements such as chromium, which decays to vanadium and thence to titanium. Thus, absorption lines of vanadium could be expected, Poznanski said.

Filippenko noted that the past few years have "yielded a bonanza of weird supernovae."

"A lot of us who have studied supernovae for several decades are amazed at the quality and quantity of data coming in recently, showing interesting new subclasses or even strange new physical classes of supernovae," he said. "It whets my appetite for what else we might find out there with these large, wide-sky surveys like the Palomar Transient Factory, Dark Energy Survey and the Large Synoptic Survey Telescope. KAIT has discovered about 800 supernovae, but these new surveys will find thousands or hundreds of thousands of supernovae."

Poznanski, too, is expecting the current Palomar Transient Factory, which uses a wide-field camera to search the sky daily for new objects, to find more supernovae like SN 2002bj. The factory is a project led by Shri Kulkarni, professor of astronomy at the California Institute of Technology (Caltech), and involves many of the co-authors on the Science Express paper, including Peter Nugent, co-leader of the Computational Cosmology Center at LBNL, who runs the search for transients.

"The Palomar survey will be able to find many rare objects, like SN 2002bj, by scanning huge parts of the sky and not limit itself to the big, bright and nearby galaxies," Poznanski said.

Coauthors with Poznanski, Filippenko, Nugent, Ganeshalingam, Leonard, Chornock and Bloom are Rollin C. Thomas, a member of the Computational Cosmology Center, and Weidong Li of UC Berkeley's Department of Astronomy.

The research was funded by the National Science Foundation, the Department of Energy, the Sylvia and Jim Katzman Foundation and the TABASGO Foundation, with observational assistance from the University of California Lick Observatory and the W. M. Keck Observatory in Hawaii.

Evidence for a thin veil of carbon has been found on the neutron star in the Cassiopeia A supernova remnant. This discovery, made with NASA's Chandra X-ray Observatory, resolves a ten-year mystery surrounding this object.

"The compact star at the center of this famous supernova remnant has been an enigma since its discovery," said Wynn Ho of the University of Southampton and lead author of a paper that appears in the November 5 issue of Nature. "Now we finally understand that it can be produced by a hot neutron star with a carbon atmosphere."

By analyzing Chandra's X-ray spectrum -- akin to a fingerprint of energy -- and applying it to theoretical models, Ho and his colleague Craig Heinke, from the University of Alberta, determined that the neutron star in Cassiopeia A, or Cas A for short, has an ultra-thin coating of carbon. This is the first time the composition of an atmosphere of an isolated neutron star has been confirmed.

The Chandra "First Light" image of Cas A in 1999 revealed a previously undetected point-like source of X-rays at the center. This object was presumed to be a neutron star, the typical remnant of an exploded star, but researchers were unable to understand its properties. Defying astronomers' expectations, this object did not show any X-ray or radio pulsations or any signs of radio pulsar activity.

By applying a model of a neutron star with a carbon atmosphere to this object, Ho and Heinke found that the region emitting X-rays would uniformly cover a typical neutron star. This would explain the lack of X-ray pulsations because -- like a lightbulb that shines consistently in all directions -- this neutron star would be unlikely to display any changes in its intensity as it rotates.

Scientists previously have used a neutron star model with a hydrogen atmosphere giving a much smaller emission area, corresponding to a hot spot on a typical neutron star, which should produce X-ray pulsations as it rotates. Interpreting the hydrogen atmosphere model without pulsations would require a tiny size, consistent only with exotic stars made of strange quark matter.

"Our carbon veil solves one of the big questions about the neutron star in Cas A," said Craig Heinke. "People have been willing to consider some weird explanations, so it's a relief to discover a less peculiar solution."

Unlike most astronomical objects, neutron stars are small enough to understand on a human scale. For example, neutron stars typically have a diameter of about 14 miles, only slightly longer than a half-marathon. The atmosphere of a neutron star is on an even smaller scale. The researchers calculate that the carbon atmosphere is only about 4 inches thick, because it has been compressed by a surface gravity that is 100 billion times stronger than on Earth.

"For people who are used to hearing about immense sizes of things in space, it might be a surprise that we can study something so small," said Ho. "It's also funny to think that such a thin veil over this star played a key role in frustrating researchers."

In Earth's time frame, the estimated age of the neutron star in Cas A is only several hundred years, making it about ten times younger than other neutron stars with detected surface emission. Therefore, the Cas A neutron star gives a unique window into the early life of a cooling neutron star.

The carbon itself comes from a combination of material that has fallen back after the supernova, and nuclear reactions on the hot surface of the neutron star which convert hydrogen and helium into carbon.

The X-ray spectrum and lack of pulsar activity suggest that the magnetic field on the surface of this neutron star is relatively weak. Similarly low magnetic fields are implied for several other young neutron stars by study of their weak X-ray pulsations. It is not known whether these neutron stars will have low magnetic fields for their entire lives, and never become radio pulsars, or whether processes in their interior will lead to the development of stronger magnetic fields as they age.

The Alps are growing just as quickly in height as they are shrinking. This paradoxical result comes from a new study by a group of German and Swiss geoscientists.

Due to glaciers and rivers, about exactly the same amount of material is eroded from the slopes of the Alps as is regenerated from the deep Earth's crust. The climatic cycles of the glacial period in Europe over the past 2.5 million years have accelerated this erosion process. In the latest volume of the science magazine Tectonophysics ( No. 474, S.236-249) the scientists show that today's uplifting of the Alps is driven by these strong climatic variations

The formation of the Alps through the collision of the two continents Africa and Europe began about approximately 55 million years ago. This led to the upthrusting of the highest European mountains, which probably already achieved its greatest height some millions of years ago. At present, however, the Swiss Alps are no longer growing as a result of this tectonic process.

Swiss geodesists, who have already been measuring the Alps with highest accuracy for decades, have observed, however, that the Alp summits, as compared to low land, rise up to one millimetre per year. Over millions of years a considerable height would have to result. But why then are the Alps not as high as the Himalayas? Researchers from the GFZ German Research Centre for Geosciences were able to calculate that mountains eroded concurrently at almost exactly the same speed.

"This mountain erosion cannot even be determined using the highly precise methods of modern geodesy," explains Professor Friedhelm v. Blanckenburg from the GFZ. "We use the rare isotope Beryllium-10, which develops in the land surface via cosmic radiation. The quicker a surface erodes, the fewer isotopes of this type are present therein." Therefore, von Blanckenburg, and the GFZ geoscientist, Dr. Hella Wittmann, have analysed this "cosmogenic" isotope in the sand of the Swiss Alps rivers and, thus, in the direct products of erosion.

How does it come about now that the Alps erode at the same speed that they rise? "Here pure upthrusting forces are at work. It is similar to an iceberg in the sea. If the top melts, the iceberg surfaces out of the water by almost the same share," explains von Blanckenburg. Thus this paradoxical situation with the Alps that through wind, water, glaciers and rock fall, they are being constantly finely eroded from the top but on the other hand, regenerated from the Earth's mantle. This phenomenon, even if already postulated theoretically has now been proven for a complete mountain range for the first time.

Thus, the Alps are constantly rising, although they have been deemed "dead" in a tectonic sense. Instead of plate forces it is the strong climatic variations since the beginning of the so-called quaternary glacial before approximately 2.5 million years, to which mountain slopes in particular have been reacting so sensitively. This holds the Alps in motion.