As China's economy continues to soar, its energy use and greenhouse gas emissions will keep on soaring as well—or so goes the conventional wisdom. A new analysis by researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) now is challenging that notion, one widely held in both the United States and China.Well before mid-century, according to a new study by Berkeley Lab's China Energy Group, that nation's energy use will level off, even as its population edges past 1.4 billion. "I think this is very good news,'' says Mark Levine, co-author of the report, "China's Energy and Carbon Emissions Outlook to 2050" and director of the group. "There's been a perception that China's rising prosperity means runaway growth in energy consumption. Our study shows this won't be the case."Along with China's rise as a world economic power have come a rapid climb in energy use and a related boost in man-made carbon dioxide emissions. In fact, China overtook the United States in 2007 as the world's leading emitter of greenhouse gases.Yet according to this new forecast, the steeply rising curve of energy demand in China will begin to moderate between 2030 and 2035 and flatten thereafter. There will come a time—within the next two decades—when the number of people in China acquiring cars, larger homes, and other accouterments of industrialized societies will peak. It's a phenomenon known as saturation. "Once nearly every household owns a refrigerator, a washing machine, air conditioners and other appliances, and once housing area per capita has stabilized, per household electricity growth will slow,'' Levine explains.Similarly, China will reach saturation in road and rail construction before the 2030-2035 time frame, resulting in very large decreases in iron and steel demand. Additionally, other energy-intensive industries will see demand for their products flatten.The Berkeley Lab report also anticipates the widespread use of electric cars, a significant drop in reliance on coal for electricity generation, and a big expansion in the use of nuclear power—all helping to drive down China's CO2 emissions. Although China has temporarily suspended approvals of new nuclear power plant construction in the wake of the disaster at Japan's Fukushima Daiichi Nuclear Power Station, the long-range forecast remains unchanged.Key to the new findings is a deeper look at patterns of energy demand in China: a "bottom-up" modeling system that develops projections of energy use in far greater detail than standard methods and which is much more time- and labor-intensive to undertake. Work on the project has been ongoing for the last four years. "Other studies don't have this kind of detail,'' says Levine. "There's no model outside of China that even comes close to having this kind of information, such as our data on housing stock and appliances."Not only does the report examine demand for appliances such as refrigerators and fans, it also makes predictions about adoption of improvements in the energy efficiency of such equipment – just as Americans are now buying more efficient washing machines, cars with better gas-mileage, and less power-hungry light bulbs.Berkeley Lab researchers Nan Zhou, David Fridley, Michael McNeil, Nina Zheng, and Jing Ke co-authored the report with Levine. Their study is a "scenario analysis" that forecasts two possible energy futures for China, one an "accelerated improvement scenario" that assumes success for a very aggressive effort to improve energy efficiency, the other a more conservative "continued improvement scenario" that meets less ambitious targets. Yet both of these scenarios, at a different pace, show similar moderation effects and a flattening of energy consumption well before 2050.Under the more aggressive scenario, energy consumption begins to flatten in 2025, just 14 years from now. The more conservative scenario sees energy consumption rates beginning to taper in 2030. By the mid-century mark, energy consumption under the "accelerated improvement scenario" will be 20 percent below that of the other.Scenario analysis is also used in more conventional forecasts, but these are typically based on macroeconomic variables such as gross domestic product and population growth. Such scenarios are developed "without reference to saturation, efficiency, or usage of energy-using devices, e.g., air conditioners,'' says the Berkeley Lab report. "For energy analysts and policymakers, this is a serious omission, in some cases calling into question the very meaning of the scenarios.''The new Berkeley Lab forecast also uses the two scenarios to examine CO2 emissions anticipated through 2050. Under the more aggressive scenario, China's emissions of the greenhouse gas are predicted to peak in 2027 at 9.7 billion metric tons. From then on, they will fall significantly, to about 7 billion metric tons by 2050. Under the more conservative scenario, CO2 emissions will reach a plateau of 12 billion metric tons by 2033, and then trail down to 11 billion metric tons at mid-century.Several assumptions about China's efforts to "decarbonize" its energy production and consumption are built into the optimistic forecasts for reductions in the growth of greenhouse gas emissions. They include:A dramatic reduction in coal's share of energy production, to as low as 30 percent by 2050, compared to 74 percent in 2005An expansion of nuclear power from 8 gigwatts in 2005 to 86 gigawatts by 2020, followed by a rise to as much as 550 gigawatts in 2050A switch to electric cars. The assumption is that urban private car ownership will reach 356 million vehicles by 2050. Under the "continued improvement scenario," 30 percent of these will be electric; under the "accelerated improvement scenario," 70 percent will be electric.
Wednesday, April 27, 2011
Thursday, April 21, 2011
The Earth may be able to recover from rising carbon dioxide emissions faster than previously thought, according to evidence from a prehistoric event analyzed by a Purdue University-led team.When faced with high levels of atmospheric carbon dioxide and rising temperatures 56 million years ago, the Earth increased its ability to pull carbon from the air. This led to a recovery that was quicker than anticipated by many models of the carbon cycle - though still on the order of tens of thousands of years, said Gabriel Bowen, the associate professor of earth and atmospheric sciences who led the study."We found that more than half of the added carbon dioxide was pulled from the atmosphere within 30,000 to 40,000 years, which is one-third of the time span previously thought," said Bowen, who also is a member of the Purdue Climate Change Research Center. "We still don't know exactly where this carbon went, but the evidence suggests it was a much more dynamic response than traditional models represent."Bowen worked with James Zachos, a professor of earth and planetary sciences at the University of California, Santa Cruz, to study the end of the Palaeocene-Eocene Thermal Maximum, an approximately 170,000-year-long period of global warming that has many features in common with the world's current situation, he said."During this prehistoric event billions of tons of carbon was released into the ocean, atmosphere and biosphere, causing warming of about 5 degrees Celsius," Bowen said. "This is a good analog for the carbon being released from fossil fuels today."Scientists have known of this prehistoric event for 20 years, but how the system recovered and returned to normal atmospheric levels has remained a mystery.Bowen and Zachos examined samples of marine and terrestrial sediments deposited throughout the event. The team measured the levels of two different types of carbon atoms, the isotopes carbon-12 and carbon-13. The ratio of these isotopes changes as carbon dioxide is drawn from or added to the atmosphere during the growth or decay of organic matter.Plants prefer carbon-12 during photosynthesis, and when they accelerate their uptake of carbon dioxide it shifts the carbon isotope ratio in the atmosphere. This shift is then reflected in the carbon isotopes present in rock minerals formed by reactions involving atmospheric carbon dioxide, Bowen said."The rate of the carbon isotope change in rock minerals tells us how rapidly the carbon dioxide was pulled from the atmosphere," he said. "We can see the fluxes of carbon dioxide in to and out of the atmosphere. At the beginning of the event we see a shift indicating that a lot of organic-derived carbon dioxide had been added to the atmosphere, and at the end of the event we see a shift indicating that a lot of carbon dioxide was taken up as organic carbon and thus removed from the atmosphere."A paper detailing the team's National Science Foundation-funded work was published in Nature Geoscience.It had been thought that a slow and fairly constant recovery began soon after excess carbon entered the atmosphere and that the weathering of rocks, called silicate weathering, dictated the timing of the response.Atmospheric carbon dioxide that reacts with silicon-based minerals in rocks is pulled from the air and captured in the end product of the reaction. This mechanism has a fairly direct correlation with the amount of carbon dioxide in the atmosphere and occurs relatively slowly, Bowen said.The changes Bowen and Zachos found during the Palaeocene-Eocene Thermal Maximum went beyond the effects expected from silicate weathering, he said."It seems there was actually a long period of higher levels of atmospheric carbon dioxide followed by a short and rapid recovery to normal levels," he said. "During the recovery, the rate at which carbon was pulled from the atmosphere was an order of magnitude greater than the slow drawdown of carbon expected from silicate weathering alone."A rapid growth of the biosphere, with a spread of forests, plants and carbon-rich soils to take in the excess carbon dioxide, could explain the quick recovery, Bowen said."Expansion of the biosphere is one plausible mechanism for the rapid recovery, but in order to take up this much carbon in forests and soils there must have first been a massive depletion of these carbon stocks," he said. "We don't currently know where all the carbon that caused this event came from, and our results suggest the troubling possibility that widespread decay or burning of large parts of the continental biosphere may have been involved."Release from a different source, such as volcanoes or sea floor sediments, may have started the event, he said.
Hammer-toothed ‘marsupial skinks' from the Australian Cenozoic1. Derrick A. Arena (A,*)2. Michael Archer (A)3. Henk Godthelp (A),4. Suzanne J. Hand (A)5. Scott Hocknull (B)A. School of Biological, Earth and Environmental Sciences, University of New South Wales, New South Wales 2052, AustraliaB. Queensland Museum South Bank, Brisbane, Queensland 4101, Australia*. Author for correspondence (firstname.lastname@example.org).Abstract:Extinct species of Malleodectes gen. nov. from Middle to Late Miocene deposits of the Riversleigh World Heritage Area, northwestern Queensland, Australia are enigmatic, highly specialized, probably snail-eating marsupials. Dentally, they closely resemble a bizarre group of living heterodont, wet forest scincid lizards from Australia (Cyclodomorphus) that may well have outcompeted them as snail-eaters when the closed forests of central Australia began to decline. Although there are scincids known from the same Miocene deposits at Riversleigh, these are relatively plesiomorphic, generalized feeders. This appears to be the most striking example known of dental convergence and possible competition between a mammal and a lizard, which in the long run worked out better for the lizards.
Wednesday, April 20, 2011
16th Annual CESM Workshop
20 - 23 June 2011
The Village, Breckenridge, Colorado
Monday, 20 June 2011
10:00 a.m. Registration
12:00 – 1:00 p.m. Lunch (on your own)
1:00 – 2:00 p.m. “State of the CESM” by Jim Hurrell, NCAR
2:00 – 3:00 p.m. CCSM Distinguished Achievement Award
3:00 – 3:30 p.m. Break
3:30 – 5:00 p.m. Poster Session (Forest Room)
5:00 – 6:30 p.m. Reception (light appetizers and cash bar) (Elk Room; Antlers A; Antlers B)
Tuesday, 21 June 2011
7:00 – 8:30 a.m. Registration and Continental Breakfast
8:30 – 12:00p.m. Atmosphere Model Working Group Meeting (Ten Mile Room)
8:30 – 12:00p.m. Paleoclimate Working Group Meeting (Tarn Room)
8:30 – 12:00p.m. Polar Climate Working Group Meeting (Aspen / Blue Spruce Room)
10:30 – 11:00 a.m. Break
12:00 – 1:30 p.m. Lunch (on your own)
1:30 – 5:00 p.m. Ocean Model Working Group Meeting (Ten Mile Room)
1:30 – 5:00 p.m. Chemistry Climate Working Group Meeting (Tarn Room)
1:30 – 5:00 p.m. Land Model Working Group Meeting (Aspen / Blue Spruce Room)
3:00 – 3:30 p.m. Break
Wednesday, 22 June 2011
7:00 – 8:30 a.m. Registration and Continental Breakfast
8:30 – 12:00 a.m. Biogeochemistry Working Group Meeting (Ten Mile Room)
8:30 – 12:00 a.m. Climate Variability Working Group Meeting (Tarn Room)
8:30 – 12:00 a.m. Land Ice Working Group Meeting (Aspen / Blue Spruce Room)
10:30 – 11:00 a.m. Break
12:00 – 2:00 p.m. Lunch (on your own)
2:00 – 3:00 p.m. Plenary Presentation – GFDL's ESM2 Series Simulations of Coupled Carbon, Climate and Ecosystems by John Dunne, NOAA / GFDL
3:00 – 3:30 p.m. Break
3:30 – 4:30 p.m. Plenary Presentation – by Jeff Kiehl, NCAR
Thursday, 23 June 2011
7:00 – 8:30 a.m. Registration and Continental Breakfast
8:30 – 12:00 p.m. Software Engineering Working Group Meeting (Aspen / Blue Spruce Room)
8:30 – 12:00 p.m. Climate Change Working Group Meeting (Ten Mile Room)
8:30 – 12:00 p.m. WACCM Working Group Meeting (Tarn Room)
10:30 – 11:00 a.m. Break
12:00 – 1:30 p.m. Discussion and Wrap-up (Ten Mile Room)
1:30 p.m. Adjourn
Link to the PDF is at the top.
The Woods Hole Research Center has released the first hectare-scale maps of canopy height, aboveground biomass, and associated carbon stock for the forests and woodlands of the conterminous United States. The multi-year project, referred to as the National Biomass and Carbon Dataset (NBCD), produced maps of these key forest attributes at an unprecedented spatial resolution of 30 m. The digital raster data set is now freely accessible from the WHRC website at www.whrc.org/nbcd.According to Dr. Josef Kellndorfer, who led the project at WHRC, "We are excited about the completion of this mapping project. The dataset represents a comprehensive assessment of forest structure and carbon stock within the lower 48 States at the beginning of the third millennium, providing an important baseline with which to improve our understanding of the United States forest resources and its link to the terrestrial carbon flux in North America. This dataset will be useful to foresters, wildlife ecologists, resource managers, and scientists alike."Volker Radeloff, professor at the University of Wisconsin-Madison, Department of Forest and Wildlife Ecology, added, "Vegetation structure data has been the holy grail for biodiversity science: absolutely essential, but unattainable for large areas. The NBCD data set fills this crucial gap and will advance of our understanding of why biodiversity is so much higher in some areas than others, and target biodiversity conservation efforts."The project was initiated in 2005 with funding from NASA's Terrestrial Ecology Program as well as support from the USGS/LANDFIRE consortium. Collaborators included the U.S. Forest Service Forest Inventory and Analysis (FIA) Program, and the National Land Cover Database (NLCD 2001) and National Elevation Dataset (NED) project teams at the USGS EROS Data Center.To produce this first-of-its-kind data set, NASA space-borne imagery (SRTM/Landsat-7), land use/land cover information (NLCD 2001), topographic survey data (NED), and extensive forest inventory data (FIA) were combined. Production of the NBCD followed an ecoregional mapping zone approach developed for the NLCD 2001 project. Across 66 individual mapping zones, spatial data, field observations, and statistical models were used to generate the canopy height, aboveground biomass, and carbon stock maps, which were then joined to form national-scale products."This effort is an excellent example of FIA partnering to marry ground and remotely-sensed data to provide natural resource information at resolutions much finer than the FIA sampling frame," said Dennis May, Forest Inventory and Analysis program manager with the U.S. Forest Service, Northern Research Station.Dr. Wayne Walker, a Center scientist who also worked on the project, added, "Maps of key forest attributes like canopy height and carbon stock have not existed for the U.S. at this level of spatial detail and consistency. They will provide ecologists and land managers with new and better information to support biodiversity conservation, wildfire risk assessment, and timber production while helping climate scientists and others to better understand the role that U.S. forests play in the global carbon cycle."
A research group has concluded that forests and other terrestrial ecosystems in the lower 48 states can sequester up to 40 percent of the nation’s fossil fuel carbon emissions, a larger amount than previously estimated – unless a drought or other major disturbance occurs.Widespread droughts, such as those that occurred in 2002 and 2006, can cut the amount of carbon sequestered by about 20 percent, the scientists concluded in a recent study that was supported by the National Science Foundation and U.S. Department of Energy.The research, published by scientists from 35 institutions in the journal Agricultural and Forest Meteorology, was based on satellite measurements and dozens of environmental observation sites in the AmeriFlux network. Not all of this data had previously been incorporated into earlier estimates, and the new study provides one of the most accurate assessments to date of the nation’s carbon balance.“With this data it appears that our forests and other vegetation can sequester as much as 40 percent of the carbon emissions in the lower 48 states,” said Beverly Law, a co-author of the study, professor in the Department of Forest Ecosystems and Society at Oregon State University, and science team chair of the AmeriFlux network.“That’s substantially higher than some previous estimates, which indicated these ecosystems could take up the equivalent of only about 30 percent of emissions or less,” Law said. “There’s still some uncertainty in these data, but it does appear that the terrestrial carbon sink is higher than believed in earlier studies.”However, the scientists cautioned that major disturbances, such as droughts, wildfires and hurricanes, can all affect the amount of carbon sequestered in a given year. Large droughts that happened twice in the U.S. in the past decade reduced the carbon sink about 20 percent, compared to a normal year.“With climate change, we may get more extreme or frequent weather events in the future than we had before,” Law said. “About half of the United States was affected by the major droughts in 2002 and 2006, which were unusually severe in their spatial extent and severity. And we’re now learning that this can have significant effects on the amount of carbon sequestered in a given year.”Carbon dioxide, when released by the burning of fossil fuels, forest fires, or other activities, is a major “greenhouse gas” and factor in global warming. But vegetation, mostly in the form of growing evergreen and deciduous forests, can play an important role in absorbing some of the excess carbon dioxide.Such information is important to understand global climate issues and develop policies, the researchers noted. This study examined the carbon budget in the U.S. from 2001 to 2006. Also playing a key role in the analysis was the PRISM climate database at OSU, a sophisticated system to monitor weather on a very localized and specific basis.The period from 2001-06, the researchers noted, had some catastrophic and unusual events, not the least of which was Hurricane Katrina and the massive destruction it caused. It also factored in the 2002 Biscuit Fire in southwest Oregon, one of the largest forest fires in modern U.S. history.The research found that the temperate forests in the eastern U.S. absorbed carbon mainly because of forest regrowth following the abandonment of agricultural lands, while some areas of the Pacific Northwest assimilated carbon during much of the year because of the region’s mild climate.Crop lands were not considered in determining the annual magnitude of the U.S. terrestrial carbon sink, because the carbon they absorb each year during growth will be soon released when the crops are harvested or their biomass burned.The study was led by Jingfeng Xiao, a research assistant professor at the Complex Systems Research Center, Institute for the Study of Earth, Oceans, and Space, at the University of New Hampshire.
Tuesday, April 19, 2011
A highly sophisticated cyber attack -- known as Advanced Persistent Threat or APT -- forced Oak Ridge National Laboratory to shut down all Internet access and email systems over the weekend.Those restrictions will remain in place until lab officials and others investigating the attack are sure the situation is well controlled and manageable, ORNL Director Thom Mason said today.Mason said he expects that email functions may be restored Tuesday on a limited basis, with no attachments allowed and restrictions on length. He said he couldn't speculate on when Internet access will be restored fully, even though the shutdown limits many of the lab's functions."We made the decision (at about midnight Friday) to close down the connection to the Internet to make sure there was no data exfiltrated from the lab while we got the system cleaned up," he said.The lab's cyber specialists had been monitoring the attack and recommended further action after it looked like efforts were underway to remove data from ORNL systems, Mason said.Mason said the APT at ORNL is similar to attacks in recent times on Google, a security company known as RSA and other government institutions and corporations."In this case, it was initiated with phishing email, which led to the download of some software that took advantage of a 'zero day exploit,' a vulnerability for which there is no patch yet issued," he said. The vulnerability involved Internet Explorer, he said.
A new study reveals that a group of ancient enzymes adapted to substantial changes in ocean temperature and acidity during the last four billion years, providing evidence that life on Early Earth evolved from a much hotter, more acidic environment to the cooler, less acidic global environment that exists today.The study found that a group of ancient enzymes known as thioredoxin were chemically stable at temperatures up to 32 degrees Celsius (58 degrees Fahrenheit) higher than their modern counterparts. The enzymes, which were several billion years old, also showed increased activity at lower pH levels -- which correspond to greater acidity."This study shows that a group of ubiquitous proteins operated in a hot, acidic environment during early life, which supports the view that the environment progressively cooled and became more alkaline between four billion and 500 million years ago," said Eric Gaucher, an associate professor in the School of Biology at the Georgia Institute of Technology.The study, which was published April 3 in the advance online edition of the journal Nature Structural & Molecular Biology, was conducted by an international team of researchers from Georgia Tech, Columbia University and the Universidad de Granada in Spain.Major funding for this study was provided by two grants from the National Aeronautics and Space Administration to Georgia Tech, a grant from the National Institutes of Health to Columbia University, and a grant from the Spanish Ministry of Science and Innovation to the Universidad de Granada.Using a technique called ancestral sequence reconstruction, Gaucher and Georgia Tech biology graduate student Zi-Ming Zhao reconstructed seven ancient thioredoxin enzymes from the three domains of life -- archaea, bacteria and eukaryote -- that date back between one and four billion years.To resurrect these enzymes, which are found in nearly all known modern organisms and are essential for life in mammals, the researchers first constructed a family tree of the more than 200 thioredoxin sequences available from the three domains of life. Then they reconstructed the sequences of the ancestral thioredoxin enzymes using statistical methods based on maximum likelihood. Finally, they synthesized the genes that encoded these sequences, expressed the ancient proteins in the cells of modern Escherichia coli bacteria and then purified the proteins."By resurrecting proteins, we are able to gather valuable information about the adaptation of extinct forms of life to climatic, ecological and physiological alterations that cannot be uncovered through fossil record examinations," said Gaucher.The reconstructed enzymes from the Precambrian period -- which ended about 542 million years ago -- were used to examine how environmental conditions, including pH and temperature, affected the evolution of the enzymes and their chemical mechanisms."Given the ancient origin of the reconstructed thioredoxin enzymes, with some of them predating the buildup of atmospheric oxygen, we thought their catalytic chemistry would be simple, but we found that thioredoxin enzymes use a complex mixture of chemical mechanisms that increases their efficiency over the simpler compounds that were available in early geochemistry," said Julio Fernández, a professor in the Department of Biological Sciences professor at Columbia University.
Monday, April 18, 2011
t was previously thought that land plants evolved from stonewort-like algae. However, new research published in BioMed Central's open access journal BMC Evolutionary Biology shows that the closest relatives to land plants are actually conjugating green algae such as Spirogyra.Ancestors of green plants began to colonise the land about 500 million years ago and it is generally accepted that they evolved from streptophyte algae (a group of green, fresh water algae). But this group of algae is very diverse and currently ranges from simple, one cell, flagellates to more complex, branching, algae such as stoneworts (Chara).It was thought that Charales were the closest relatives to land plants because they share (amongst other characteristics) a similar method of fertilisation, oogamy, with a large egg and small swimming sperm. For flowering plants this sperm is contained within pollen grains. In contrast, another type of streptophytes, the Zygnematales, use conjugation, a method of reproduction where the gametes are of equal size, isogamy, and one or both crawl, amoeba-like, into a fertilization tube where they meet and fuse.Some phylogenetic analysis had been done previously, on a smaller number of genes, which seemed to support the Charales theory. However, a multinational team, involving researchers in Germany and Canada, analysed genetic divergence in 129 genes from 40 different green plant taxa. This data showed that, despite the differences in reproductive strategy, the closest living relatives to land plants are in fact the Zygnematales.Dr Becker explained, "It seems that Zygnematales have lost oogamy and their ability to produce sperm and egg cells, and instead, possibly due to selection pressure in the absence of free water, use conjugation for reproduction. Investigation of such a large number of genes has shown that, despite their apparent simplicity, Zygnematales have genetic traces of other complex traits also associated with green land plants. Consequently Zygnematales true place as the closest living relative to land plants has been revealed."
A reptile that lived 275-million years ago in what is now Oklahoma is giving paleontologists a glimpse of the oldest known toothache.Led by Professor Robert Reisz, the chair of the Department of Biology at the University of Toronto Mississauga, scientists found evidence of bone damage due to oral infection in Paleozoic reptiles as they adapted to living on land. Their findings, published online in the journal Naturwissenschaften – The Nature of Science, predate the previous record for oral and dental disease in a terrestrial vertebrate by nearly 200 million years."Not only does this fossil extend our understanding of dental disease, it reveals the advantages and disadvantages that certain creatures faced as their teeth evolved to feed on both meat and plants," says Reisz. "In this case, as with humans, it may have increased their susceptibility to oral infections."The researchers investigated the jaws of several well-preserved specimens of Labidosaurus hamatus, a 275-million-year-old terrestrial reptile from North America. One specimen stood out because of missing teeth and associated erosion of the jaw bone. With the aid of CT-scanning, Reisz and colleagues found evidence of a massive infection. This resulted in the loss of several teeth, as well as bone destruction in the jaw in the form of an abscess and internal loss of bone tissue.As the ancestors of advanced reptiles adapted to life on land, many evolved dental and cranial specializations to feed more efficiently on other animals and to incorporate high-fiber plant leaves and stems into their diet. The primitive dental pattern in which teeth were loosely attached to the jaws and continuously replaced, changed in some animals. Teeth became strongly attached to the jaw, with little or no tooth replacement. This was clearly advantageous to some early reptiles, allowing them to chew their food and thus improve nutrient absorption. The abundance and global distribution of Labidosauris and its kin suggest that it was an evolutionary success.However, Reisz and his colleagues suggest that as this reptile lost the ability to replace teeth, the likelihood of infections of the jaw, resulting from damage to the teeth, increased substantially. This is because prolonged exposure of the dental pulp cavity of heavily worn or damaged teeth to oral bacteria was much greater than in other animals that quickly replaced their teeth.
In the seven years Cassini has spent orbiting Saturn, the spacecraft has sent back mountains of data that has changed our view of the ringed planet and its moons. Saturn's largest moon, Titan, has been a particular focus of attention because of its dense, complex atmosphere, its weather and its lakes and oceans.Now it looks as if Titan is even stranger still. The evidence comes from careful observations of Titan's orbit and rotation. This indicates that Titan has an orbit similar to our Moon's: it always presents the same face towards Saturn and its axis of rotation tilts by about 0.3 degrees.Together, these data allow astronomers to work out Titan's moment of inertia and this throws up something interesting. The numbers indicate that Titan's moment of inertia can only be explained if it is a solid body that is denser near the surface than it is at its centre.That's just plain weird--unthinkable really, given what we know about how planets and moons form.But there is another explanation, however: that Titan isn't solid at all.Today, Rose-Marie Baland and buddies at the Royal Observatory of Belgium in Brussels, crunch some numbers to see whether a liquid model is compatible with the measured moment of inertia. "We assume the presence of a liquid water ocean beneath an ice shell and consider the gravitational and pressure torques arising between the different layers of the satellite," they say.Their conclusion is that Titan's moment of inertia could well be explained by the presence of liquid ocean beneath an icy shell.
Thursday, April 14, 2011
Velociraptors hunted by night while big plant-eating dinosaurs browsed around the clock, according to a paper on the eyes of fossil animals published on-line this week in Science Express.That overturns the conventional wisdom that dinosaurs were active by day while early mammals scurried around at night, said Ryosuke Motani, a geologist at the University of California at Davis, and a co-author of the paper."It was a surprise, but it makes sense," Motani said.It's also providing insight into how ecology influences the evolution of animal shape and form over tens of millions of years, according to Motani and collaborator Lars Schmitz, a postdoctoral researcher at UC Davis."These authors' conclusion that these dinosaurs were active diurnally and nocturnally challenges a general dogma--that nocturnality in that time was mostly restricted to mammals," says H. Richard Lane, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research.Motani and Schmitz worked out the dinosaurs' daily habits by studying their eyes.Dinosaurs, lizards and birds all have a bony ring called the "scleral ring" in their eyes, although this is lacking in mammals and crocodiles.Schmitz and Motani measured the inner and outer dimensions of this ring, plus the size of the eye socket, in 33 fossils of dinosaurs, ancestral birds and pterosaurs--and in 164 living species.Day-active, or diurnal animals have a small opening in the middle of the ring while the opening is much larger in nocturnal animals.Cathemeral animals--active in both day and night--tend to be in between.But the size of these features is also affected by ancestry.For example, two closely related animals might have similar eye shape even if one is active by day and the other by night: the shape of the eye is constrained by ancestry, and that could bias the results.Schmitz and Motani developed a computer program to separate the "ecological signal" from this "phylogenetic signal."The results of that analysis are in a separate paper published simultaneously in the journal Evolution.By looking at a 164 living species, they could confirm that the eye measurements were accurate in predicting whether animals were active by day, by night or around the clock.Then they applied the technique to fossils, including plant-eating and carnivorous dinosaurs, flying reptiles called pterosaurs and ancestral birds.The big plant-eating dinosaurs were active day and night, probably because they had to eat most of the time, except for the hottest hours of the day when they avoided overheating.Modern megaherbivores like elephants show the same activity pattern, Motani said.Velociraptors and other small carnivores were night hunters.Schmitz and Motani were not able to study big carnivores such as Tyrannosaurus rex, because there are no fossils with sufficiently well-preserved eyes.Flying creatures, including early birds and pterosaurs, were mostly day-active, although some of the pterosaurs--including a filter-feeding animal that probably lived like a duck, and a fish-eating pterosaur--were apparently night-active."This strongly suggests that ecology drives activity," Schmitz said.
Wednesday, April 13, 2011
Birds are known more for their senses of vision and hearing than smell, but new research suggests that millions of years ago, the winged critters also boasted a better sense for scents.A study published today by scientists at the University of Calgary, the Royal Tyrrell Museum and the Ohio University College of Osteopathic Medicine tested the long-standing view that during the evolution from dinosaurs to birds, the sense of smell declined as birds developed heightened senses of vision, hearing and balance for flight. The team compared the olfactory bulbs in the brains of 157 species of dinosaurs and ancient and modern-day birds.The findings, published in the journal Proceedings of the Royal Society B, dispute that theory. The scientists discovered that the sense of smell actually increased in early bird evolution, peaking millions of years ago during a time when the ancestors of modern-day birds competed with dinosaurs and more ancient branches of the bird family."It was previously believed that birds were so busy developing vision, balance and coordination for flight that their sense of smell was scaled way back," said Darla Zelenitsky, assistant professor of paleontology at the University of Calgary and lead author of the research. "Surprisingly, our research shows that the sense of smell actually improved during dinosaur-bird evolution, like vision and balance."In an effort to conduct the most detailed study to date on the evolution of sense of smell, the research team made CT scans of dinosaurs and extinct bird skulls to reconstruct their brains. The scientists used the scans to determine the size of the creatures' olfactory bulbs, a part of the brain involved in the sense of smell. Among modern-day birds and mammals, larger bulbs correspond to a heightened sense of smell."Of course the actual brain tissue is long gone from the fossil skulls," said study co-author Lawrence Witmer, Chang Professor of Paleontology at the Ohio University College of Osteopathic Medicine, "but we can use CT scanning to visualize the cavity that the brain once occupied and then generate 3D computer renderings of the olfactory bulbs and other brain parts."The study revealed details of how birds inherited their sense of smell from dinosaurs."The oldest known bird, Archaeopteryx, inherited its sense of smell from small meat-eating dinosaurs about 150 million years ago," said François Therrien, curator of dinosaur palaeoecology at the Royal Tyrrell Museum and co-author of the study. "Later, around 95 million years ago, the ancestor of all modern birds evolved even better olfactory capabilities."How well did dinosaurs smell, especially compared to modern animals? Although scientists haven't been able to make an exhaustive comparison, Witmer noted that the ancient beasts most likely exhibited a range of olfactory abilities. T. rex had large olfactory bulbs, which probably aided the creature in tracking prey, finding carcasses and possibly even territorial behavior, while a sense of smell was probably less important to dinosaurs such as Triceratops, he said.The team was able to make some direct comparisons between the ancient and modern-day animals under study. Archaeopteryx, for example, had a sense of smell similar to pigeons, which rely on odors for a number of behaviors."Turkey vultures and albatrosses are birds well known for their keen sense of smell, which they use to search for food or navigate over large areas," says Zelenitsky. "Our discovery that small Velociraptor-like dinosaurs, like Bambiraptor, had a sense of smell as developed as turkey vultures and albatrosses suggests that smell may have played an important role while these dinosaurs hunted for food."If early birds had such powerful sniffers, why do birds have a reputation for a poor sense of smell? Witmer explained that the new study confirms that the most common birds that humans encounter today—the backyard perching birds such as crows and finches, as well as pet parrots—indeed have smaller olfactory bulbs and weaker senses of smell. It may be no coincidence that the latter are also the cleverest birds, suggesting that their enhanced smarts may have decreased the need for a strong sniffer, he said.
A team of scientists exploring rocks around Loch Torridon have discovered the remarkably preserved remains of organisms that once lived on the bottom of ancient lake beds as long as a billion (1000 million) years ago.These fossils illuminate a key moment in the history of evolution when life made the leap from tiny, simple bacterial (prokaryote) cells towards larger, more complex (eukaryotic) cells which would make photosynthesis and sexual reproduction possible.The team, from Oxford University, the University of Sheffield and Boston College, report their findings in this week's Nature."These new fossils show that the move toward complex algal cells living in lakes on land had started over a billion years ago, much earlier than had been thought," said Professor Martin Brasier of Oxford University's Department of Earth Sciences, an author of the paper."These new cells differ from their bacterial ancestors in that they have specialized structures including a nucleus, as well as mitochondria and chloroplasts – which are vital for photosynthesis. They also undergo sexual reproduction, leading to much more rapid rates of evolutionary turnover."Some of these ancient fossils are so finely ornamented, and so large and complex, that they are evidence for a surprisingly early start for the emergence of complex eukaryote cells on land. The researchers believe that it was from complex cells such as these that green algae and green land plants – everything from lettuce to larch trees – were able to evolve and colonise the land.Dr Charles Wellman, Reader in Palaeobiology in the Department of Animal and Plant Sciences at the University of Sheffield, an author of the paper, said: "It is generally considered that life originated in the ocean and that the important developments in the early evolution of life took place in the marine environment: the origin of prokaryotes, eukaryotes, sex, multicellularity etc. During this time the continents are often considered to have been essentially barren of life - or at the most with an insignificant microbial biota dominated by cyanobacteria."We have discovered evidence for complex life on land from 1 billion year old deposits from Scotland. This suggests that life on land at this time was more abundant and complex than anticipated. It also opens the intriguing possibility that some of the major events in the early history of life may have taken place on land and not entirely within the marine realm."Professor Brasier said: "It may even be that the sort of conditions found in the ancient lakes around Loch Torridon favoured a key step in this transformation, which involved the incorporation of symbiotic bacteria into the cell to form chloroplasts, rather than this occurring in the sea as usually envisaged."
Paleontologists from the American Museum of Natural History and the Chinese Academy of Sciences announce the discovery of Liaoconodon hui, a complete fossil mammal from the Mesozoic found in China that includes the long-sought transitional middle ear. The specimen shows the bones associated with hearing in mammals— the malleus, incus, and ectotympanic— decoupled from the lower jaw, as had been predicted, but were held in place by an ossified cartilage that rested in a groove on the lower jaw. The new research, published in Nature this week, also suggests that the middle ear evolved at least twice in mammals, for monotremes and for the marsupial-placental group.[...]The new fossil described this week, Liaoconodon hui, fills the gap in knowledge between the basal, early mammaliaforms like Morganucodon, where the middle ear bones are part of the mandible and the definitive middle ear of living and fossil mammals. Liaoconodon hui is a medium-sized mammal for the Mesozioc (35.7 cm long from nose to tip of tail, or about 14 inches) and dates from 125 to 122 million years. It is named in part for the bountiful fossil beds in Liaoning, China, where it was found. The species name, hui, honors paleontologist Yaoming Hu who graduated from the American Museum of Natural History-supported doctoral program and recently passed away. The fossil is particularly complete, and its skull was prepared from both dorsal and ventral sides, allowing Meng and colleagues to see that the incus and malleus have detached from the lower jaw to form part of the middle ear. These bones remain linked to the jaw by the ossified Meckel's cartilage that rests in the groove on the lower jaw. The team hypothesizes that in this early mammal, the ear drum was stabilized with the ossified cartilage as a supporting structure."Before we did not know the detailed morphology of how the bones of the middle ear detached, or the purpose of the ossified cartilage," says Meng. "Liaoconodon hui changes previous interpretations because we now know the detailed morphology of the transitional mammal and can propose that the ossified cartilage is a stabilizer."Also presented in the new research paper is a detailed phylogenetic analysis of some features of living and fossil mammals. Looking at features associated with bones and the groove on the lower jaw, which indicated the presence of ossified Meckel's cartilage, it appears that the middle ear probably evolved twice, in monotremes and in placentals and marsupials.