rise of sea level

University of Toronto and Oregon State University geophysicists have shown that should the West Antarctic Ice Sheet collapse and melt in a warming world – as many scientists are concerned it will – it is the coastlines of North America and of nations in the southern Indian Ocean that will face the greatest threats from rising sea levels.

The catastrophic increase in sea level, already projected to average between 16 and 17 feet around the world, would be almost 21 feet in such places as Washington, D.C., scientists say, putting it largely underwater. Many coastal areas would be devastated. Much of Southern Florida would disappear, according to researchers at Oregon State University.

“There is widespread concern that the West Antarctic Ice Sheet may be prone to collapse, resulting in a rise in global sea levels,” says geophysicist Jerry X. Mitrovica, who, along with physics graduate student Natalya Gomez and Oregon State University geoscientist Peter Clark, are the authors of a new study to be published in the February 6 issue of the journal Science. “We’ve been able to calculate that not only will the rise in sea levels at most coastal sites be significantly higher than previously expected, but that the sea-level change will be highly variable around the globe,” adds Gomez.

“Scientists are particularly worried about the ice sheet because it is largely marine-based, which means that the bedrock underneath most of the ice sits under sea level,” says Mitrovica, director of the Earth System Evolution Program at the Canadian Institute for Advanced Research. “The West Antarctic is fringed by ice shelves which act to stabilize the ice sheet – these shelves are sensitive to global warming, and if they break up, the ice sheet will have a lot less impediment to collapse.” This concern was reinforced further in a recent study led by Eric Steig of the University of Washington that showed that the entire region is indeed warming.

“The typical estimate of the sea-level change is five metres, a value arrived at by taking the total volume of the West Antarctic Ice Sheet, converting it to water and spreading it evenly across the oceans, says Mitrovica. “However, this estimate is far too simplified because it ignores three significant effects:

• when an ice sheet melts, its gravitational pull on the ocean is reduced and water moves away from it. The net effect is that the sea level actually falls within 2,000 km of a melting ice sheet, and rises progressively further away from it. If the West Antarctic Ice Sheet collapses, sea level will fall close to the Antarctic and will rise much more than the expected estimate in the northern hemisphere because of this gravitational effect;
• the depression in the Antarctic bedrock that currently sits under the weight of the ice sheet will become filled with water if the ice sheet collapses. However, the size of this hole will shrink as the region rebounds after the ice disappears, pushing some of the water out into the ocean, and this effect will further contribute to the sea-level rise;
• the melting of the West Antarctic Ice Sheet will actually cause the Earth’s rotation axis to shift rather dramatically – approximately 500 metres from its present position if the entire ice sheet melts. This shift will move water from the southern Atlantic and Pacific oceans northward toward North America and into the southern Indian Ocean.

“The net effect of all of these processes is that if the West Antarctic Ice Sheet collapses, the rise in sea levels around many coastal regions will be as much as 25 per cent more than expected, for a total of between six and seven metres if the whole ice sheet melts,” says Mitrovica. “That’s a lot of additional water, particularly around such highly populated areas as Washington, D.C., New York City, and the California coastline.”

Digital animation of what various sea-level rise scenarios might look like for up to six metres is at http://www.cresis.ku.edu/research/data/sea_level_rise.

“There is still some important debate as to how much ice would actually disappear if the West Antarctic Ice sheet collapses – some fraction of the ice sheet may remain quite stable,” he says. “But, whatever happens, our work shows that the sea-level rise that would occur at many populated coastal sites would be much larger than one would estimate by simply distributing the meltwater evenly. Any careful assessment of the sea-level hazard associated with the loss of major ice reservoirs must, of course, account for the sea-level fingerprint of other sources of meltwater, namely Greenland, the East Antarctic and mountain glaciers. The most important lesson is that scientists and policy makers should focus on projections that avoid simplistic assumptions.”

The research was funded with support from the Canadian Institute for Advanced Research, the Natural Sciences and Engineering Research Council of Canada, the John Simon Guggenheim Memorial Foundation and the US National Sciences Foundation.

Source-www.sciencedaily.com

THE CARTESIAN DIVER

new twist for the great classic
Cartesian divers were first noted by a student of Galileo Galilee! Some people back in those days thought its mysterious dives and accents in the water smacked of dark magic, as witnessed by the name it was sometimes called: Devil's Diver. The advent of clear plastic bottles made Cartesian divers popular in school science classes, as well they should be. What a cool way to learn about density, buoyancy, compression of gases, etc.
Unfortunately, some diver designs are either too expensive for large groups, or they hide what's going on inside the diver. For example, pen caps and modeling clay are cheap enough for everyone to make, but you can't see the air compressing and the water rushing in. Using clear or translucent eye droppers costs at least a dollar each. Not bad if you're just making one at home, but quite a bit of money if you are making them with a large group. I offer two designs to fill the void. If my design is not what you are looking for

HOW TO MAKE THE VORTEX

two un-crushed, 2-liter soda bottles
Try to get bottles that have not been really crushed, because the dents that remain can interfere with the spinning water.
1/2" diameter PVC plastic pipe.
It is our good fortune that very cheap and easy to find 1/2" PVC pipe fits snuggly inside 2-liter bottles. When used to connect two bottles, the pipe keeps them from flopping around.
Some hardware stores might sell it by the foot (you only need 2 inches per project). From other places, like building centers, you will have to buy 5 or 10 feet at a time. It is still little more than a dollar for 10 feet. PVC pipe is white. Do not get "CPVC" pipe, which is more expensive and a tanish color. One more confusing thing: 1/2" diameter pipe is actually bigger than 1/2". Go by what it says on the pipe, not by actually measuring the diameter.
clear plastic food wrap
The only really challenging part of this project is making the bottles completely sealed--no leaks. The best way to do it is with plastic wrap. By stretching the plastic tightly as it is wrapped around the bottles, it seals very well.
electrical tape or duct tape or masking tape; scissors; hacksaw (or just a hacksaw blade)
Duct tape is best. The hacksaw or hacksaw blade is for cutting the plastic pipe.
cold water, or refrigeration or ice or snow or cold weather to make it cold.
I know it seems a bit strange to be concerned about air and water temperature as we seal the two bottles together. The reason behind it is quite interesting. I go into it more in the Activities and Explanations page.
For building this project, you should know this much: It is important that the air and water in the bottles be cold when they are being sealed. As the air warms up, it will expand a little. Because it's trapped inside, the air pressure inside the bottles becomes a little higher than the air pressure outside. That's good, because it keeps the bottles firm, just like the higher air pressure in a bicycle tire keeps the tire from going flat.
Without the higher pressure inside, the bottles will dent a little. Because they are no longer perfectly round, it's harder to make a good vortex. Fortunately, this is easy to prevent by keeping things cool when sealing the bottles.
Step 1
Cut a 2" long piece of pipe.
PVC pipe is easy to cut and it only takes a few seconds. Even if you don't have a hacksaw frame, you can cut with just a blade if you wrap a little tape around as a handle. Hack saws are much safer than any other kind of saw.
I am a believer in letting even young kids participate as much as possible, so I offer this illustration as a proven way kids (green hands) can do some sawing, while you (blue hands) maintain control of the saw. Because of the way the pipe is supported on both ends, it doesn't slide around.
Here you can see a fast and safe jig for cutting, made of a scrap of wood and 5 nails. The hacksaw slides against two nails that automatically cut a 2" piece. It's worth making if you are working with a group.
When you're done sawing, clean out the plastic "crud" that sticks to the end of the pipe where you made the cut. Use your fingernail.
Step 2
Prepare the bottles for sealing.
These sub-steps don't have to be done in any particular order:
*Rinse out bottles.
*Peel off labels. Save a colorful piece for the next part.
*Cut some confetti from the plastic labels you just peeled off. They become tracers in the vortex (they remind me of the house spinning around in the Wizard of Oz). No piece should be larger than the finger nail on your pinky. Put the pieces into one of the bottles.
*Cut a piece of electrical tape 3" long, or cut duct tape into a a 3/4" slice, 3" long. Wrap it tightly around the middle of the pipe. This tape will keep the pipe from falling into one bottle or the other.
*Fill one bottle about 2/3 full of the coldest water you can get. For example, if there is a drinking fountain with chilled water, it would be worth it to catch it in a cup and pour it into the bottle. Alternately, you could but half a handful of crushed ice or snow in both bottles, or you could put the bottles in the refrigerator or outside (if it's cold) for half an hour.
If the kids making the vortex are very young (kindergarten or first grade), only fill the bottle half full. It will be easier to carry and easier to start the vortex.
Step 3
Just before you wrap.
Push the pipe into the filled bottle until it gets hard to push (because of the tape). Turn the other bottle upside down and push it on the other side of the pipe. Push and twist it pretty hard so it squishes some of the tape.
Just before sealing the bottles, turn them upside down so the empty bottle fills (a few drops of water might leak out). This will cool the air inside. The top bottle will probably dent in a little, which means the air in the system is contracting. Pull the bottles apart for an instant to let more air in, so the bottle is not dented anymore. Do this just before sealing so the air doesn't have a chance to warm up much.
Step 4
Seal the bottles together.
The key to sealing the bottles is to keep the plastic wrap tight as you wrap it on.
Take the roll out of the box and hold it in one hand. Start wrapping the end around the bottles with the other hand. At some point, the wrapped part won't slip off even when you pull very hard. You should notice the plastic stretching over the handles. That is where the seal will be made. Wrap at least 10 tight wraps around the bottles. I know I'm repeating myself, but if you don't apply the plastic under stretching tension, it won't seal.
Although the bottles should now be sealed, wrap some duct tape or electrical tape a few of times around the plastic. This keeps it from unraveling, and it keeps the bottles from separating when you lift by the top bottle.
Step 5
Use it!
Turn the bottles over. Grab the very top an swish it in a circular motion two or three times, then stop suddenly. This will give the water enough circular momentum to create the vortex.
If the bottle dents, don't worry. It will fill out in a hour or so, as the water warms--if you sealed it well. Until then, at the same time you swishing the top end in a circle to get the water moving, squeeze the the bottom bottle. When the dent is on the bottom, it doesn't interfere with the vortex.

thaumatrope

The thaumatrope is a good warm up for the movie wheel and it only takes a minute to make. The mysterious message written on the thaumatrope pattern will appear when you spin it. Interestingly, the thaumatrope preceded --and led to the invention of-- the movie wheel.
What you need.
thread, tape and scissors
The thread could be dental floss or even a couple of very thin rubber band cut open and tied together.
STEP 1
Cut out the thaumatrope pattern and fold in half.

Check the printed paper to make sure it did not re-scale the size of the pattern. If it says something like, "Scaled-60%" try another browser. Netscape seems to be the worst at re-scaling. Cut on the solid lines. Fold carefully right on the dashed line so the printed part is on the outside. Using a strait edge or a table corner will help make the fold straight.
STEP 2
Tape in the string and tape halves together.
Tape a string onto the non-print side so it splits one of the halves, as shown. Then tape the halves shut. You should now have a two-dimensional rectangle with letters on both sides a string splitting it right through the middle.
STEP 3
Try it out
Twirl the thaumatrope by rolling the string between thumb and forefinger of each hand as fast as you can. If you are using dental floss, sometimes you have to roll it awhile before it works smoothly. If using a thin rubber band, pull it slightly as you spin it. You should see "PERSISTENCE OF VISION." That expression was used to explain how we perceived animation. It is being superceded by the expression, "phi phenomenon."

Scientists Propose Creation Of New Type Of Seed Bank

While an international seed bank in a Norwegian island has been gathering news about its agricultural collection, a group of U.S. scientists has just published an article outlining a different kind of seed bank, one that proposes the gathering of wild species –– at intervals in the future –– effectively capturing evolution in action.
In the October issue of Bioscience, Steven J. Franks of Fordham University, Susan J. Mazer of the University of California, Santa Barbara, and a group of colleagues, have proposed a method of collecting and storing seeds of natural plant populations. They argue for the collection of many species in a way that evolutionary responses to future changes in climate can be detected. They call it the "Resurrection Initiative."
"In contrast to existing seed banks, which exist primarily for conservation, this collection would be for research that would allow a greater understanding of evolution," said Franks.
"This seed collection would form an important resource that can be used for many types of research, just as GenBank –– the collection of genetic sequences and information –– forms a key resource for research in genetics and genomics," said Franks.
"Typically, seed banks are focused on the preservation of agricultural species or other plant species of strong economic interest, say, forest species, forest trees," said Mazer. This is to make sure that scientists can maintain a genetically diverse seed pool in the event of some kind of ecological calamity that requires the replenishing of seeds from a certain part of the world or from certain species. "But that implies a relatively static view of a seed bank, a snapshot forever of what a species provides."
Evolutionary biologists recognize that the gene pool of any species is a dynamic resource that changes over time as a result of random events such as highly destructive climatic events like hurricanes, but also through sustained and ongoing processes like evolution by natural selection.
While most scientists agree that the climate is changing, the extent to which species will be able to evolve to keep up with these changes is unknown.
According to the article, the only way that scientists can detect the results of those sorts of calamitous changes –– and test evolutionary predictions about what sorts of changes might occur over time –– is to sample seed banks in a repeated fashion. Then they must compare the attributes of the gene pools that are sampled at different times to a baseline.
"One way that we can obtain this baseline is by collecting seeds at a given point in time and archiving them under ideal environmental conditions, so that they all stay alive, and so that 10, 20, and 30 years down the road, we can compare them to seeds that we collect in the future to see how the gene pool has changed," explained Mazer.
This approach will allow a number of things that a one-time, seed-sampling event doesn't. Scientists can evaluate the result of the effects of climate change, land use change, and other kinds of environmental changes such as the spread of disease on the gene pool.
"Currently seed banks don't allow this for a couple of reasons," said Mazer. "First, they focus on species that have been under cultivation for a long period. Species that have been under cultivation have relatively low levels of genetic variation –– because we have been selecting them only for the attributes that we want. Wild species, by contrast, contain a high degree of genetic variation in almost any trait that we might examine."
Agricultural species are often selected to have a predictable flowering time, a predictable seed size –– and a predictable degree of tolerance for drought, salt, or heavy metals. By contrast, wild species retain a much greater degree of genetic diversity in all of these traits.
Mazer explained that scientists don't know whether or not the environmental changes that are ongoing, due to changes in climate or land use practices, are reducing the amount of genetic variation in the wild. If they are, the only way it can be detected will be by sampling representative seeds from a large number of populations at very regular intervals.
"The approach that we would use is not simply to collect seeds over various time intervals and to archive them, but in the future to raise them in a common environment comparing seeds that were collected in 2010, 2030, and 2050, for example," said Mazer. "If we found, for example, that the plants that come from seeds that were collected 50 years from now flower much earlier than those that were collected today, we could logically infer that natural selection over 50 years had favored plants, that is genotypes that flowered earlier and earlier, relative to those that delayed flowering."
Mazer explained that scientists and the public have been thrilled recently by an increase in the understanding of the value of seed banks, and in particular with the seed bank that is underway in Norway, called the Svalbard Global Seed Vault, on the island of Spitsbergen.
"However, that kind of seed bank doesn't finish the job," said Mazer. "The Norwegian seed bank is planning to preserve hundreds of thousands of varieties of agricultural plant species, but most of those samples represent only a tiny fraction of that which you would find in a wild population of a wild species." Nor does it allow for insights into the evolutionary process, enabled by the combination of seed banking and subsequent raising of plants as proposed by the "Resurrection Initiative."

Major Discovery May Unleash Solar Revolution

MIT researchers have developed a new catalyst, consisting of cobalt metal, phosphate and an electrode. When the catalyst is placed in water and electricity runs through the electrode, oxygen gas is produced. When another catalyst is used to produce hydrogen gas, the oxygen and hydrogen can be combined inside a fuel cell, creating carbon-free electricity to power a house or an electric car, day or night. Photo / MIT News Office
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In a revolutionary leap that could transform solar power from a marginal, boutique alternative into a mainstream energy source, MIT researchers have overcome a major barrier to large-scale solar power: storing energy for use when the sun doesn't shine.Until now, solar power has been a daytime-only energy source, because storing extra solar energy for later use is prohibitively expensive and grossly inefficient. With today's announcement, MIT researchers have hit upon a simple, inexpensive, highly efficient process for storing solar energy.Requiring nothing but abundant, non-toxic natural materials, this discovery could unlock the most potent, carbon-free energy source of all: the sun. 'This is the nirvana of what we've been talking about for years,' said MIT's Daniel Nocera, the Henry Dreyfus Professor of Energy at MIT and senior author of a paper describing the work in the July 31 issue of Science. 'Solar power has always been a limited, far-off solution. Now we can seriously think about solar power as unlimited and soon.'Inspired by the photosynthesis performed by plants, Nocera and Matthew Kanan, a postdoctoral fellow in Nocera's lab, have developed an unprecedented process that will allow the sun's energy to be used to split water into hydrogen and oxygen gases. Later, the oxygen and hydrogen may be recombined inside a fuel cell, creating carbon-free electricity to power your house or your electric car, day or night.The key component in Nocera and Kanan's new process is a new catalyst that produces oxygen gas from water; another catalyst produces valuable hydrogen gas. The new catalyst consists of cobalt metal, phosphate and an electrode, placed in water. When electricity -- whether from a photovoltaic cell, a wind turbine or any other source -- runs through the electrode, the cobalt and phosphate form a thin film on the electrode, and oxygen gas is produced.Combined with another catalyst, such as platinum, that can produce hydrogen gas from water, the system can duplicate the water splitting reaction that occurs during photosynthesis.The new catalyst works at room temperature, in neutral pH water, and it's easy to set up, Nocera said. 'That's why I know this is going to work. It's so easy to implement,' he said.'Giant leap' for clean energySunlight has the greatest potential of any power source to solve the world's energy problems, said Nocera. In one hour, enough sunlight strikes the Earth to provide the entire planet's energy needs for one year.James Barber, a leader in the study of photosynthesis who was not involved in this research, called the discovery by Nocera and Kanan a 'giant leap' toward generating clean, carbon-free energy on a massive scale.'This is a major discovery with enormous implications for the future prosperity of humankind,' said Barber, the Ernst Chain Professor of Biochemistry at Imperial College London. 'The importance of their discovery cannot be overstated since it opens up the door for developing new technologies for energy production thus reducing our dependence for fossil fuels and addressing the global climate change problem.''Just the beginning'Currently available electrolyzers, which split water with electricity and are often used industrially, are not suited for artificial photosynthesis because they are very expensive and require a highly basic (non-benign) environment that has little to do with the conditions under which photosynthesis operates.More engineering work needs to be done to integrate the new scientific discovery into existing photovoltaic systems, but Nocera said he is confident that such systems will become a reality.'This is just the beginning,' said Nocera, principal investigator for the Solar Revolution Project funded by the Chesonis Family Foundation and co-Director of the Eni-MIT Solar Frontiers Center. 'The scientific community is really going to run with this.'Nocera hopes that within 10 years, homeowners will be able to power their homes in daylight through photovoltaic cells, while using excess solar energy to produce hydrogen and oxygen to power their own household fuel cell. Electricity-by-wire from a central source could be a thing of the past.

Quantum 'Traffic Jam' in High-Temperature Superconductors

Scientists at the U.S. Department of Energy's Brookhaven National Laboratory, in collaboration with colleagues at Cornell University, Tokyo University, the University of California, Berkeley, and the University of Colorado, have uncovered the first experimental evidence for why the transition temperature of high-temperature superconductors — the temperature at which these materials carry electrical current with no resistance — cannot simply be elevated by increasing the electrons' binding energy. The research — to be published in the August 28, 2008, issue of Nature — demonstrates how, as electron-pair binding energy increases, the electrons' tendency to get caught in a quantum mechanical 'traffic jam' overwhelms the interactions needed for the material to act as a superconductor — a freely flowing fluid of electron pairs.'We've made movies to show this traffic jam as a function of energy. At some energies, the traffic is moving and at others the electron traffic is completely blocked,' said physicist J.C. Seamus Davis of Brookhaven National Laboratory and Cornell University, lead author on the paper. Davis will be giving a Pagels Memorial Public Lecture to announce these results at the Aspen Center for Physics on August 27.Understanding the detailed mechanism for how quantum traffic jams (technically referred to as 'Mottness' after the late Sir Neville Mott of Cambridge, UK) impact superconductivity in cuprates may point scientists toward new materials that can be made to act as superconductors at significantly higher temperatures suitable for real-world applications such as zero-loss energy generation and transmission systems and more powerful computers.The idea that increasing binding energy could elevate a superconductor's transition temperature stems from the mechanism underlying conventional superconductors' ability to carry current with no resistance. In those materials, which operate close to absolute zero (0 kelvin, or -273 degrees Celsius), electrons carry current by forming so-called Cooper pairs. The more strongly bound those electron pairs, the higher the transition temperature of the superconductor.But unlike those metallic superconductors, the newer forms of high-temperature superconductors, first discovered some 20 years ago, originate from non-metallic, Mott-insulating materials. Elevating these materials’ pair-binding energy only appears to push the transition temperature farther down, closer to absolute zero rather than toward the desired goal of room temperature or above.“It has been a frustrating and embarrassing problem to explain why this is the case,” Davis said. Davis’s research now offers an explanation.In the insulating 'parent' materials from which high-temperature superconductors arise, which are typically made of materials containing copper and oxygen, each copper atom has one 'free' electron. These electrons, however, are stuck in a Mott insulating state — the quantum traffic jam — and cannot move around. By removing a few of the electrons — a process called 'hole doping' — the remaining electrons can start to flow from one copper atom to the next. In essence, this turns the material from an insulator to a metallic state, but one with the startling property that it superconducts — it carries electrical current effortlessly without any losses of energy.'It’s like taking some cars off the highway during rush hour. All of a sudden, the traffic starts to move,' said Davis.cuprate high-temperature superconductorThe proposed mechanism for how these materials carry the current depends on magnetic interactions between the electrons causing them to form superconducting Cooper pairs. Davis's research, which used 'quasiparticle interference imaging' with a scanning tunneling microscope to study the electronic structure of a cuprate superconductor, indicates that those magnetic interactions get stronger as you remove holes from the system. So, even as the binding energy, or ability of electrons to link up in pairs, gets higher, the 'Mottness,' or quantum traffic-jam effect, increases even more rapidly and diminishes the ability of the supercurrent to flow.'In essence, the research shows that what is believed to be required to increase the superconductivity in these systems — stronger magnetic interactions — also pushes the system closer to the 'quantum traffic-jam' status, where lack of holes locks the electrons into positions from which they cannot move. It's like gassing up the cars and then jamming them all onto the highway at once. There's lots of energy, but no ability to go anywhere,' Davis said.With this evidence pointing the scientists to a more precise theoretical understanding of the problem, they can now begin to explore solutions. 'We need to look for materials with such strong pairing but which don’t exhibit this Mottness or 'quantum traffic-jam' effect,' Davis said.Scientists at Brookhaven are now investigating promising new materials in which the basic elements are iron and arsenic instead of copper and oxygen. 'Our hope is that they will have less 'traffic-jam' effect while having stronger electron pairing,' Davis said. Techniques developed for the current study should allow them to find out.This research was funded primarily by the Brookhaven Lab's Laboratory-Directed Research and Development Fund, by the Office of Basic Energy Sciences within DOE's Office of Science, by a Grant-in-Aid for Scientific Research from the Ministry of Science and Education (Japan), and by the 21st Century COE Program of the Japan Society for the Promotion of Science.