Ice age extinction shaped Australian plant diversity

This is an electron microscope image of a fossil Acacia flower from the study fossil site in Southern Australia. -  Greg Jordan
This is an electron microscope image of a fossil Acacia flower from the study fossil site in Southern Australia. – Greg Jordan

Researchers have shown that part of Australia’s rich plant diversity was wiped out by the ice ages, proving that extinction, instead of evolution, influences biodiversity.

The research led by the University of Melbourne and University of Tasmania has shown that plant diversity in South East Australia was as rich as some of the most diverse places in the world, and that most of these species went extinct during the ice ages, probably about one million years ago.

The team’s work was published in the prestigious journal Proceedings of the National Academy of Sciences.

Dr Kale Sniderman of the University of Melbourne’s School of Earth Sciences said the findings show extinction is just as important to diversity of organisms as evolution.

“Traditionally scientists believed some places have more species than others because species evolved more rapidly in these places. We have overthrown this theory, which emphasizes evolution, by showing that extinction may be more important, ” he said.

The study compared two regions of Southern Australia and South Africa.

“South-western Australia has a huge diversity of tough-leaved shrubs and trees such as eucalypts, Banksia, Grevilleas and Acacias, making it one of the most biodiverse places on earth,” Dr Sniderman said.

“The southern tip of South Africa is even richer, with astonishing numbers of similar kinds of plants like proteas and ericas.”

Scientists have long maintained that this diversity is somehow related to the poor soils and dry summers of these places.

For the study researchers analysed plant fossils that accumulated in an ancient lake in South Eastern Australia. They found the region had at least as many tough-leaved plants 1.5 million years ago as Western Australia and South Africa do today.

The results were entirely unexpected.

“As Australia dried out over the past several million years, rainforest plants largely disappeared from most of the continent,” said Dr Sniderman

“It has been thought that this drying trend allowed Australia’s characteristic tough-leaved plants to expand and became more diverse. We have shown that the climate variability of the ice ages not only drove rainforest plants to extinction but also a remarkable number of tough-leaved, shrubby plants,” he said.

Dr Greg Jordan of the School of Plant Sciences at the University of Tasmanian said not only has the study overturned current thought on the role of extinction in plant diversity, it has implications for understanding how Australian plant diversity will deal with current and future climate change.

“The species that went extinct in SE Australia during the ice ages were likely to be the ones most sensitive to rapid climate change, meaning that the species that now grow in eastern Australia may be more capable of tolerating rapid changes than predicted by current science,” he said.

“However, the species in hotspots of diversity like Western Australia may be much more sensitive to future climate change, because they have been protected from past climate changes.”

Hoodoos — key to earthquakes?

In the absence of long-term instrumental data, fragile rock formations, called hoodoos, may be key to understanding seismic hazard risk. In this study, researchers consider two hoodoos in Red Rock Canyon region to put limits on expected intensity of ground motion from earthquakes along the Garlock fault.

Hoodoos can be found in desert regions and are highly susceptible to erosion that makes their age uncertain. Despite that uncertainty, existing unfractured hoodoos, tall spires of sedimentary rock, may help put limits on ground motion associated with recent events by understanding the minimal force necessary to break the shafts made primarily of relatively soft sandstone.

The Garlock fault region features an active strike-slip fault. Anooshehpoor, et al., estimated the tensile strength of two hoodoos and considered previously published physical evidence of fault offsets that suggest at least one large earthquake, resulting in seven meters (23 feet) of slip, in the last 550 years. And yet, the hoodoos are still intact, suggesting median or low level of ground motion associated with the large quakes in this region.

While the age of the hoodoos cannot be exactly ascertained, the authors argue that these rocks can still serve as a valuable tool in constraining ground motion and thus contribute to the development of probabilistic seismic hazard assessments in the area.

Middle East river basin has lost Dead Sea-sized quantity of water

Already strained by water scarcity and political tensions, the arid Middle East along the Tigris and Euphrates rivers is losing critical water reserves at a rapid pace, from Turkey upstream to Syria, Iran and Iraq below.

Unable to conduct measurements on the ground in the politically unstable region, UC Irvine scientists and colleagues used data from space to uncover the extent of the problem. They took measurements from NASA’s Gravity Recovery and Climate Experiment satellites, and found that between 2003 and 2010, the four nations lost 144 cubic kilometers (117 million acre feet) of water – nearly equivalent to all the water in the Dead Sea. The depletion was especially striking after a drought struck the area in 2007. Researchers attribute the bulk of it – about 60 percent – to pumping of water from underground reservoirs.

They concluded that the Tigris-Euphrates watershed is drying up at a pace second only to that in India. “This rate is among the largest liquid freshwater losses on the continents,” the scientists report in a paper to be published online Feb. 15 in Water Resources Research, a journal of the American Geophysical Union.

Water management is a complex issue in the Middle East, “a region that is dealing with limited water resources and competing stakeholders,” said Katalyn Voss, lead author and a water policy fellow with the University of California’s Center for Hydrologic Modeling in Irvine.

Turkey has jurisdiction over the Tigris and Euphrates headwaters, as well as the reservoirs and infrastructure of its Southeastern Anatolia Project, which dictates how much water flows downstream into Syria, Iran and Iraq. And due to varied interpretations of international laws, the basin does not have coordinated water management. Turkey’s control of water distribution to adjacent countries has caused tension, such as during the 2007 drought, when it continued to divert water to irrigate its own agricultural land.

“That decline in stream flow put a lot of pressure on downstream neighbors,” Voss said. “Both the United Nations and anecdotal reports from area residents note that once stream flow declined, the northern part of Iraq had to switch to groundwater. In a fragile social, economic and political environment, this did not help.”

The Gravity Recovery and Climate Experiment, which NASA launched in 2002 to measure the Earth’s local gravitation pull from space, is providing a vital picture of global trends in water storage, said hydrologist Jay Famiglietti, the study’s principal investigator and a UC Irvine professor of Earth system science.

GRACE is “like having a giant scale in the sky,” he said. “Whenever you do international work, it’s exceedingly difficult to obtain data from different countries. For political, economic or security reasons, neighbors don’t want each other to know how much water they’re using. In regions like the Middle East, where data are relatively inaccessible, satellite observations are among the few options.”

Rising or falling water reserves alter the Earth’s mass in particular areas, influencing the strength of the local gravitational attraction. By periodically quantifying that gravity, the satellites provide information about how much each region’s water storage changes over time.

The 754,000-square-kilometer (291,000-square-mile) Tigris-Euphrates River Basin jumped out as a hot spot when researchers from UC Irvine, NASA’s Goddard Space Flight Center and the National Center for Atmospheric Research looked at global water trends. Over the seven-year period, they calculated that available water there shrank by an average of 20 cubic kilometers (16 million acre feet) annually.

Meanwhile, the area’s demand for freshwater is rising at the worst possible time. “They just do not have that much water to begin with, and they’re in a part of the world that will be experiencing less rainfall with climate change. Those dry areas are getting drier,” Famiglietti said. “Everyone in the world’s arid regions needs to manage their available water resources as best they can.”

India joined with Asia 10 million years later than previously thought

The peaks of the Himalayas are a modern remnant of massive tectonic forces that fused India with Asia tens of millions of years ago. Previous estimates have suggested this collision occurred about 50 million years ago, as India, moving northward at a rapid pace, crushed up against Eurasia. The crumple zone between the two plates gave rise to the Himalayas, which today bear geologic traces of both India and Asia. Geologists have sought to characterize the rocks of the Himalayas in order to retrace one of the planet’s most dramatic tectonic collisions.

Now researchers at MIT have found that the collision between India and Asia occurred only 40 million years ago – 10 million years later than previously thought. The scientists analyzed the composition of rocks from two regions in the Himalayas, and discovered evidence of two separate collisional events: As India crept steadily northward, it first collided with a string of islands 50 million years ago, before plowing into the Eurasian continental plate 10 million years later.

Oliver Jagoutz, assistant professor of geology in MIT’s Department of Earth, Atmospheric and Planetary Sciences, says the results, which will be published in Earth and Planetary Science Letters, change the timeline for a well-known tectonic story.

“India came running full speed at Asia and boom, they collided,” says Jagoutz, an author of the paper. “But we actually don’t think it was one collision ? this changes dramatically the way we think India works.”

‘How great was Greater India?’

In particular, Jagoutz says, the group’s findings may change scientists’ ideas about the size of India before it collided with Asia. At the time of collision, part of the ancient Indian plate – known as “Greater India” – slid underneath the Eurasian plate.

What we see of India’s surface today is much smaller than it was 50 million years ago. It’s not clear how much of India lies beneath Asia, but scientists believe the answer may come partly from knowing how fast the Indian plate migrates, and exactly when the continent collided with Asia.

“The real question is, ‘How great was Greater India?'” Jagoutz says. “If you know when India hit, you know the size of Greater India.”

By dating the Indian-Eurasian collision to 10 million years later than previous estimates, Jagoutz and his colleagues conclude that Greater India must have been much smaller than scientists have thought.

“India moved more than 10 centimeters a year,” Jagoutz says. “Ten million years [later] is 1,000 kilometers less in convergence. That is a real difference.”

Leafing through the literature

To pinpoint exactly when the Indian-Eurasian collision occurred, the team first looked to a similar but more recent tectonic example. Over the last 2 million years, the Australian continental plate slowly collided with a string of islands known as the Sunda Arc. Geologists have studied the region as an example of an early-stage continental collision.

Jagoutz and his colleagues reviewed the geologic literature on Oceania’s rock composition. In particular, the team looked for telltale isotopes – chemical elements that morph depending on factors like time and tectonic deformation. The researchers identified two main isotopic systems in the region’s rocks: one in which the element lutetium decays to hafnium, and another in which samarium decays to neodymium. From their analysis of the literature, the researchers found that rocks high in neodymium and hafnium isotopes likely formed before Australia collided with the islands. Rocks high in neodymium and hafnium probably formed after the collision.

Heading to the Himalayas

Once the team identified the isotopic signatures for collision, it looked for similar signatures in rocks gathered from the Himalayas.

Since 2000, Jagoutz has trekked to the northwest corner of the Himalayas, a region of Pakistan and India called the Kohistan-Ladakh Arc. This block of mountains is thought to have been a string of islands that was sandwiched between the two continents as they collided. Jagoutz traversed the mountainous terrain with pack mules and sledgehammers, carving out rock samples from the region’s northern and southern borders. His team has brought back three tons of rocks, which he and his colleagues analyzed for signature isotopes.

The researchers split the rocks, and separated out more than 3,000 zircons – micron-long crystals containing isotopic ratios. Jagoutz and his colleagues first determined the age of each zircon using another isotopic system, in which uranium turns slowly to lead with time. The team then measured the ratios of strontium to neodymium, and lutetium to hafnium, to determine the presence of a collision, keeping track of where each zircon was originally found (along the region’s northern or southern border).

The team found a very clear signature: Rocks older than 50 million years contained exactly the same ratio of isotopes in both the northern and southern samples. However, Jagoutz found that rocks younger than 50 million years, along the southern boundary of the Kohistan-Ladakh Arc, suddenly exhibited a range of isotopic ratios, indicating a dramatic tectonic event. Along the arc’s northern boundary, the same sudden change in isotopes occurs, but only in rocks younger than 40 million years.

Taken together, the evidence supports a new timeline of collisional events: Fifty million years ago, India collided with a string of islands, pushing the island arc northward. Ten million years later, India collided with the Eurasian plate, sandwiching the string of islands, now known as the Kohistan-Ladakh Arc, between the massive continents.

“If you actually go back in the literature to the 1970s and ’80s, people thought this was the right way,” Jagoutz says. “Then somehow the literature went in another direction, and people largely forgot this possibility. Now this opens up a lot of new ideas.”

Hydrothermal liquefaction — the most promising path to a sustainable bio-oil production

<IMG SRC="/Images/311672449.jpg" WIDTH="350" HEIGHT="256" BORDER="0" ALT="The graphs show the contents of oxygen, hydrogen and carbon in HTL-oil before and after upgrading, compared to other fuel types. – Mørup et al., Energy & Fuels, 2012, 26 (9), 5944-5953″>
The graphs show the contents of oxygen, hydrogen and carbon in HTL-oil before and after upgrading, compared to other fuel types. – Mørup et al., Energy & Fuels, 2012, 26 (9), 5944-5953

A new generation of the HTL process can convert all kinds of biomasses to crude bio-oil, which is sufficiently similar to fossil crude oil that a simple thermal upgrade and existing refinery technology can be employed to subsequently obtain all the liquid fuels we know today. What is more, the HTL process only consumes approximately 10-15 percent of the energy in the feedstock biomass, yielding an energy efficiency of 85-90 percent.

To emphasize, the HTL process accepts all biomasses from modern society – sewage sludge, manure, wood, compost and plant material along with waste from households, meat factories, dairy production and similar industries.

It is by far the most feedstock flexible of any liquid fuel producing process, including pyrolysis, bio-ethanol, gasification with Fischer-Tropsch or catalytic upgrading of different vegetable or agro-industrial residual oils, and does not carry higher costs than these.

Hydrothermal liquefaction is basically pressure cooking, but instead of cooking the biomass in batches, one pot-full at a time, this new generation of HTL is based on flow production, where the biomass is injected into a 400 °C pre-heated reactor, “cooked” under high pressure for ~15 minutes and then quickly cooled down to 70°C.

At 400°C and high pressure the water is in a supercritical state, neither liquid nor gas, at which it easily decomposes the biomass. The process is environmentally friendly, since no harmful solvents are involved, and the energy efficiency is very high: The HTL process only consumes approximately 10-15% of the energy in the feedstock biomass, because the heat energy is recycled between the heating and cooling of the process medium.

The wet medium means that HTL readily accepts moist or wet biomasses, such as those mentioned above. Wet biomasses are in vast majority on Earth. All other known processes for liquid bio-fuel production either require expensive drying or only make use of a limited proportion of the biomass, e.g. the carbohydrate content.

The water phase emanating from the HTL process has low carbon contents and can either be recycled into the process or ultimately be purified to attain drinking water quality, which is the long-term goal. As such HTL replaces the burden of disposal with the benefit of recycling.

The HTL process has the following benefits:

  • Crude HTL oil has high heating values of approximately 35-39 MJ/kg on a dry ash free basis

  • The HTL process only consumes approximately 10-15% of the energy in the feedstock biomass, yielding an energy efficiency of 85-90%
  • Crude HTL oil has very low oxygen, sulphur and water content (compared to e.g. pyrolysis oil which typically contains approx. 50% water)
  • HTL oil recovers more than 70% of the feedstock carbon content (single pass)
  • HTL oil is storage stable, and has comparatively low upgrading requirements, due in part to a high fraction of middle distillates in the crude oil. It is much less upgrading intensive than e.g. pyrolysis oil, which needs immediate upgrading in order not to deteriorate.

The bio-oil from HTL can be used as-produced in heavy engines or it can be hydrogenated or thermally upgraded to obtain diesel-, gasoline- or jet-fuels by existing refinery technology. In this sense, HTL bio-oil is directly comparable to fossil crude oil. This is unique among liquid bio-fuels and means that it can directly enter the existing fuel distribution network for automotive transportation in any concentration, giving it full drop-in properties.

In Denmark, Aarhus University and Aalborg University are in partnership on HTL research at all levels. In Aarhus, Dept. of Chemistry focuses on fundamental understanding of the process and quick surveys of the effects of different feedstocks and catalysts along with subsequent upgrading. Dept. of Agro-Ecology develops energy crops while Dept. of Engineering works on pilot-scale HTL. The latter is pursued even more vigorously at Aalborg University (Dept. of Energy Technology), which focuses strongly on pilot-scale production and process efficiency, as well as upgrading of HTL bio-oil along with end user testing of oils and upgraded distillates in engines and turbines. The Dept. of Biotechnology, Chemistry and Environmental Engineering, AAU Esbjerg, directs its activities towards extracting value not only from the oil, but also from the effluents.

The combined efforts and unique results already obtained hold promise of another energy technology endeavor in Denmark comparable only to the breakthrough of the windmill-industry in the 1980’s.

Study rebuts hypothesis that comet attacks ended 9,000-year-old Clovis culture

Rebutting a speculative hypothesis that comet explosions changed Earth’s climate sufficiently to end the Clovis culture in North America about 13,000 years ago, Sandia lead author Mark Boslough and researchers from 14 academic institutions assert that other explanations must be found for the apparent disappearance.

“There’s no plausible mechanism to get airbursts over an entire continent,” said Boslough, a physicist. “For this and other reasons, we conclude that the impact hypothesis is, unfortunately, bogus.”

In a December 2012 American Geophysical Union monograph, first available in January, the researchers point out that no appropriately sized impact craters from that time period have been discovered, nor have any unambiguously “shocked” materials been found.

In addition, proposed fragmentation and explosion mechanisms “do not conserve energy or momentum,” a basic law of physics that must be satisfied for impact-caused climate change to have validity, the authors write.

Also absent are physics-based models that support the impact hypothesis. Models that do exist, write the authors, contradict the asteroid-impact hypothesizers.

The authors also charge that “several independent researchers have been unable to reproduce reported results” and that samples presented in support of the asteroid impact hypothesis were later discovered by carbon dating to be contaminated with modern material.

The Boslough trail

Boslough has a decades-long history of successfully interpreting the effects of comet and asteroid collisions.

His credibility was on the line on in July 1994 when Eos, the widely read newsletter of the American Geophysical Union, ran a front-page prediction by a Sandia National Laboratories team, led by Boslough, that under certain conditions plumes from the collision of comet Shoemaker-Levy 9 with the planet Jupiter would be visible from Earth.

The Sandia team – Boslough, Dave Crawford, Allen Robinson and Tim Trucano – were alone among the world’s scientists in offering that possibility.

“It was a gamble and could have been embarrassing if we were wrong,” said Boslough. “But I had been watching while Shoemaker-Levy 9 made its way across the heavens and realized it would be close enough to the horizon of Jupiter that the plumes would show.” His reasoning was backed by simulations from the world’s first massively parallel processing supercomputer, Sandia’s Intel Paragon.

On the one hand, it was a chance to check the new Paragon’s logic against real events, a shakedown run for the defense-oriented machine. On the other, it was a hold-your-breath prediction, a kind of Babe Ruth moment when the Babe is reputed to have pointed to the spot in the center field bleachers he intended to hit the next ball. No other scientists were willing to point the same way, partly due to previous failures in predicting the behavior of comets Kohoutek and Halley, and partly because most astronomers believed the plumes would be hidden behind Jupiter’s bulk.

That the plumes indeed proved visible started Boslough on his own trajectory as a media touchstone for things asteroidal and meteoritic.

It didn’t hurt that, when he stands before television cameras to discuss celestial impacts, his earnest manner, expressive gestures and extraterrestrial subject matter make him seem a combination of Carl Sagan and Luke Skywalker, or perhaps Tom Sawyer and Indiana Jones.

Standing in jeans, work shirt and hiking boots for the Discovery Channel at the site in Siberia where a mysterious explosion occurred 105 years ago, or discussing it at Sandia with his supercomputer simulations in bold colors on a big screen behind him, the rangy, 6-foot-3 Sandia researcher vividly and accurately explained why the mysterious explosion at Tunguska that decimated hundreds of square miles of trees and whose ejected debris was seen as far away as London most probably was caused neither by flying saucers drunkenly ramming a hillside (a proposed hypothesis) nor by an asteroid striking the Earth’s surface, but rather by the fireball of an asteroid airburst – an asteroid exploding high above ground, like a nuclear bomb, compressed to implosion as it plunged deeper into Earth’s thickening, increasingly resistive atmosphere. The governing physics, he said, was precisely the same as for the airburst on Jupiter.

Among later triumphs, Boslough was the Sandia component of a National Geographic team flown to the Libyan Desert to make sense of strange yellow-green glass worn as jewelry by pharaohs in days past. Boslough’s take: It was the result of heat on desert sands from a hypervelocity impact caused by an even bigger asteroid burst.

In the present case

In the Clovis case, Boslough felt that his ideas were taken further than he could accept when other researchers claimed that the purported demise of Clovis civilization in North America was the result of climate change produced by a cluster of comet fragments striking Earth.

In a widely reported press conference announcing the Clovis comet hypothesis in 2007, proponents showed a National Geographic animation based on one of Boslough’s simulations as inspiration for their idea.

Indiana Jones-style, Boslough responded. Confronted by apparently hard asteroid evidence, as well as a Nova documentary and an article in the journal Science, all purportedly showing his error in rebutting the comet hypothesis, Boslough ordered carbon dating of the major evidence provided by the opposition: nanodiamond-bearing carbon spherules associated with the shock of an asteroid’s impact. The tests found the alleged 13,000-year-old carbon to be of very recent formation.

While this raised red flags to those already critical of the impact hypothesis, “I never said the samples were salted,” Boslough said carefully. “I said they were contaminated.”

That find, along with irregularities reported in the background of one member of the opposing team, was enough for Nova to remove the entire episode from its list of science shows available for streaming, Boslough said.

“Just because a culture changed from Clovis to Folsom spear points didn’t mean their civilization collapsed,” he said. “They probably just used another technology. It’s like saying the phonograph culture collapsed and was replaced by the iPod culture.”

Evidence of geological ‘facelift’ in the Appalachians

This is a waterfall in the rejuvenated portion of the Cullasaja River basin. -  Karl Wegmann, NC State University
This is a waterfall in the rejuvenated portion of the Cullasaja River basin. – Karl Wegmann, NC State University

How does a mountain range maintain its youthful, rugged appearance after 200 million years without tectonic activity? Try a geological facelift – courtesy of the earth’s mantle.

Researchers from North Carolina State University noticed that a portion of the Appalachian Mountains in western North Carolina near the Cullasaja River basin was topographically quite different from its surroundings. They found two distinct landscapes in the basin: an upper portion with gentle, rounded hills, where the average distance from valley to mountain top was about 500 feet; and a lower portion where the valley bottom to ridgeline elevation difference was 2,500 feet, hills were steep, and there was an abundance of waterfalls. The researchers believed they could use this unique topography to decipher the more recent geologic history of the region.

The Appalachian mountain range was formed between 325 to 260 million years ago by tectonic activity – when tectonic plates underneath the earth’s surface collided and pushed the mountains up. Around 230 million years ago, the Atlantic Ocean basin began to open, and this also affected the regional topography. But geologists knew that there hadn’t been any significant tectonic activity in the region since then.

“Conventional wisdom holds that in the absence of tectonic activity, mountainous terrain gets eroded and beveled down, so the terrain isn’t as dramatic,” says Sean Gallen, NC State graduate student in marine, earth and atmospheric sciences. “When we noticed that this area looked more like younger mountain ranges instead of the older, rounded, rolling topography around it, we wanted to figure out what was going on.”

Gallen and Karl Wegmann, an assistant professor of marine, earth and atmospheric sciences at NC State, decided to look at the waterfalls in the area, because they would have formed as the topography changed. By measuring the rate of erosion for the falls they could extrapolate their age, and therefore calculate how long ago this particular region was “rejuvenated” or lifted up. They found that these particular waterfalls were about 8 million years old, which indicated that the landscape must have been raised up around the same time.

But without tectonic activity, how did the uplift occur? Gallen and Wegmann point to the earth’s mantle as the most likely culprit. “The earth’s outer shell is the crust, but the next layer down – the mantle – is essentially a very viscous fluid,” Wegmann says. “When it’s warm it can well up, pushing the crust up like a big blister. If a heavy portion of the crust underneath the Appalachians ‘broke off,’ so to speak, this area floated upward on top of the blister. In this case, our best hypothesis is that mantle dynamics rejuvenated the landscape.”

The researchers’ findings appear in Geological Society of America Today. Del Bohnenstiehl, NC State associate professor of marine, earth and atmospheric sciences, contributed to the work.