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  #1  
Old 05-30-2004, 09:49 PM
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We are all dimmed: Earth's golden age of sunshine has faded

Bank Holiday sunseekers this weekend may find it harder to get a tan. And cinema-goers emerging from the global warming blockbuster, The Day After Tomorrow, will have something new to worry about. For scientists have discovered the awful truth; we are all dimmed.

New research shows that much less sunlight is reaching the earth than 50 years ago. "Global dimming", as it has inevitably become called, has been suspected for nearly 20 years, since a Swiss geography researcher, routinely checking sunshine levels across Europe in 1985, found that they had dropped, even on the brightest days. Studies all around the world found similar results, showing drops in sunlight ranging from 2 to 37 per cent since the 1950s.

The research, published in Science, is the first to prove that the dimming is a global phenomenon. Scientists at the New Jersey and California Institutes of Technology remembered how Leonardo da Vinci had worked out that the dark side of the moon was illuminated by sunlight reflected from the Earth. By measuring this "Earthshine" they worked out that the world is about 10 per cent darker than half a century ago.

Scientists are divided over whether global dimming is a natural phenomenon or caused by pollution, such as soot particles emitted from car exhausts, and global warming, which evaporates more water from the Earth, causing more clouds. Professor Philip R Goode, who led the study, told The Independent on Sunday that the way the dimming has varied suggests that it may be a natural phenomenon.

Whatever the cause, there could be massive effects on farming and on attempts to capture solar energy as the earth "dims down".
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Old 05-30-2004, 10:18 PM
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Day After Tomorrow" Ice Age "Impossible," Expert Says

Stefan Lovgren
for National Geographic News
May 27, 2004

In the new movie The Day After Tomorrow, abrupt climate change plunges the planet into total chaos. As tornadoes rip through Hollywood landmarks and grapefruit-size hail pounds Tokyo, New York City turns into an icy wasteland—all in a matter of days.

It may just be a high-octane summer blockbuster, but environmentalists hope The Day After Tomorrow will serve as a wake-up call about global climate change.

National Geographic News spoke with Tom Prugh—senior editor at the Worldwatch Institute in Washington, D.C., and an expert on climate change—to hear what he thought of the movie, which he saw at an advance screening.


The Statue of Liberty is engulfed by rising waters in a scene from The Day After Tomorrow. The natural disaster movie opens this Friday.



So should we brace ourselves for another ice age?

No, I don't think so. The scenario in the movie is fictional. Like some other Hollywood movies that claim to be based on true stories, there's a kernel of truth that is then pumped full of steroids and given cosmetic surgery.

But is global warming real?

The overwhelming scientific consensus is that global warming is real, and that it's upon us now. In the last century, the average temperature of the Earth has warmed roughly 1° Fahrenheit [0.56° Celsius]. That means an enormous additional amount of heat energy has been built into the system, and there are serious consequences to that warming.

What role does human activity play in global warming?

The atmosphere of the Earth is like a blanket that traps heat. It keeps the temperature at the surface of the Earth about 50° or 60° [Fahrenheit/28° or 33° Celsius] warmer than it would be otherwise, which is great because it makes the world a pleasant place to live. But humans have been adding to the gases that help trap this heat.

We've been adding to the stock of carbon dioxide in the atmosphere by taking coal, oil, and natural gas out of the ground and burning them as fuels. Combined with deforestation, this has added around a third of the amount of carbon in the atmosphere.

And what does this do the welfare of the Earth?

If you think of an automobile engine—when you step on the accelerator, the engine speeds up because you're putting more energy into it by increasing the fuel flow, so everything runs harder and hotter and faster. The extremes get more extreme.

That's what's happening with the climate. We're stepping on the accelerator by adding greenhouse gases to the climate and increasing heat energy in the system.

How does climate change manifest itself?

Ocean levels are rising, because water expands as it heats up. Since there is more energy in the system, storms may become more frequent and more violent. Increased incidents of flooding create heavier runoffs and soil erosion. Indirect effects of climate change can also cause entire species to go extinct.

How realistic is this movie?

It has a kernel of truth, although it has been "Hollywoodized." There is evidence that abrupt climate change has happened a couple of times in the last 13,000 years, but it's never happened in a few days, as it does in the movie. That's completely impossible.

What is the ocean conveyor belt referred to in the movie, and what is its importance to the Earth's climate?

It's the system of currents that flows around the oceans of the world and carries heat from the tropics to the northern latitudes. There is evidence that the North Atlantic branch of the current has failed in the distant past—8,200 and 12,700 years ago—causing a great cooling of the climate.

In the movie, the influx of fresh water, caused by the melting of a massive ice sheet, changes the salinity of the oceans, shutting down the Gulf Stream. Could that happen?

In theory, that is realistic. Salty water is heavier than fresh water. When the cold, salty current reaches the northern latitudes and gives out its heat, the current actually sinks and flows back along the bottom of the ocean toward the tropics.

When then there's a lot of fresh water added to that current, it may stop flowing, because it's not dense enough to sink anymore. In the past, retreating glaciers dumped enormous amounts of fresh water very suddenly into the North Atlantic, and the currents stopped.

What about the superstorms depicted in the movie, which form like hurricanes over North America, Europe, and Asia? Are they realistic?

No. Hurricanes form over waters and tend to break up and dissipate when they reach shore. They can't get the energy to keep going anymore.

One of the effects created by the superstorms in the movie is the pulling down of supercool air from the troposphere that freezes people in a matter of seconds. There is nothing that suggests this could happen.

Could another ice age happen?

It's unlikely. Even if there were a continued influx of fresh water that weakened or stopped the North Atlantic current, any cooling effect that might create would be swamped by the warming that would continue to happen in the meantime.

But if abrupt climate change has happened in the past, before the industrial revolution, isn't this just part of a natural cycle that is, in a sense, inevitable?

Certainly the climate has, to some extent, a mind of its own. But that's not to say we're not having an influence on what the climate is, what it does, and how it behaves.

We've taken a great deal of carbon that used to be locked up in the Earth in the form of coal and undisturbed oil and natural gas and released it into the atmosphere. That carbon hadn't been there in the atmosphere for millions and millions of years.

It's simply naive to think that's not going to have an effect on the climate.

So what do you say to skeptics who dispute the seriousness of global warming?

Most don't dispute that the climate is warming and that human activity has a great deal to do with that. Even the most vociferous of the climate skeptics have pretty much stopped saying that global warming is not happening.

Actually, science benefits from having skeptics. They challenge assumptions and arguments and force people to go back and get more data.

Do you think the catastrophic events in the film may be so extreme that audiences may not take the climate change issue seriously?

I hope people will come away with the lesson that we need to be more careful with the climate that we're fooling around with—not that they need to worry about buying property in Mexico because the Northern Hemisphere is going to be locked up in an icebox.

People should have a good time, but I don't think they should take this as a reason to laugh off climate change. I hope this becomes a teachable moment for people and shows that we are doing serious damage to the climate.

Any particular aspects about the film that you liked?

I liked how it used shots from space to give you a sense of how huge and powerful the climate really is. One of the key lessons of the film is that this is a very big, very complex system that we don't understand very well. Since we're conducting a giant experiment with this huge, complicated, poorly understood system, weird and unexpected stuff is probably going to happen.

I don't think anyone thinks abrupt climate change is likely any time soon, but the probability is not zero.

Do you think the general public appreciates and fully understands the threats that global warming pose?

I hope they understand that climate change is happening now. It's affecting everyone who is alive on the planet, and it will inevitably affect their children and their children's children. I have a ten-year-old son, and I want to do everything that I can do to ensure that the world he grows up in is as wonderful and pleasant as the world we got now.

So what can people do about this problem?

They can do a great deal. If millions of people turn off the lights when they leave the room, it makes an enormous difference on how much carbon winds up in the air. Most people believe their electricity comes from renewable or nuclear power or hydroelectric power, but more than half of the electricity generated in the United States comes from coal.

When you leave the light on all night long, that one act is directly responsible for putting a couple of more pounds of carbon into the atmosphere.

I would urge people to go see the movie. I thought it was a lot of fun. I would also urge them to drive to the movie theater together with a few friends [to conserve gasoline and put less exhaust into the atmosphere] and turn out all the lights in the house before they leave.
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Old 05-31-2004, 01:40 AM
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We call a light drizzle "Oregon Sunshine"

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Old 05-31-2004, 01:59 PM
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There was a study conducted on the effects of jet airplane contrails, composed of water vapor and CO. They are ineffect, artificial clouds. Those performing the study believed the contrails would cause a dimming of sunlight, as records indicated it was cooler during the day and warmer at night, generally speaking, over the last century. There was no "control" sample, however.

Then, on 9/11, when all air traffic was grounded for a few days, the temperature went back up a few degrees and "normalized". It was interesting to hear about, just a short on the "Science" channel or something.

I saw the movie yesterday. Science aside, it was entertaining.
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Old 07-13-2006, 09:02 PM
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Issue 124 , July 2006
The return of nuclear fusion?
by Fred Pearce
The world's biggest ever nuclear fusion reactor is about to begin construction in the hills of Provence. But with persistent doubts over fusion's capacity to generate energy efficiently and a raft of engineering conundrums, is this really money well spent?
The author's book "The Last Generation: How nature will take her revenge for climate change" is published in June by Eden Project Books
They call themselves "fusion gypsies"—scientists who have travelled the world, moving from one nuclear reactor to the next, living the dream that some day, somewhere, they can re-create the reactions that take place in the heart of the stars to generate huge amounts of cheap, clean electricity for the world.

Their goal is nuclear power, but not as we know it. This is fusion and not fission. Fission involves mining, processing and irradiating vast amounts of uranium, and leaving behind an even larger legacy of radioactive waste with half-lives stretching into the next ice age. Whereas, say the fusion gypsies, a small vanload of fuel supplied to a fusion power station could supply the electricity needs of a city of 1m people for a year, and leave behind only paltry amounts of radioactive waste that will decay to nothing within a century.

Fission reactors split atoms to make power; fusion reactors force the elemental particles of the universe together till they fuse, releasing energy in the process. Fusion powers the sun, the gypsies say, and one day it could power the world's electricity grids too.

Fusion research got going in the 1950s. The first fusion gypsies are approaching retirement. But scientific progress has been slow and funding sporadic. They have yet to see a watt of power delivered to any grid anywhere. But earlier this year, after more than a decade in the doldrums, the gypsies had their biggest boost, when governments representing most of the world's population decided to invest $10bn in trying to make the dream come true.

This summer, the fusion gypsies are reassembling in the wooded hills of Provence in southern France, where a new machine is to be built. Britons, Australians, Russians, Americans, Germans, Chinese, Japanese Czechs and many others are united now in a last stand to prove to the world they were right all along. John How, a bearded, sandalled Brit was the pioneer. He bought himself a farmhouse a couple of years ago in Provence in anticipation of just this moment. Now he can settle down at last, he told me, after a career stretching from Australia to Germany, France and Britain. "It's now or never for fusion power," he said.

The moment seems right. As oil prices soar, as concern grows about global warming, and as politicians balance the potential of conventional nuclear power and renewables, there is a growing need for a new source of electricity that combines the capacity of a nuclear power plant with the cleanness and safety of a wind farm. Fusion could, eventually, be the answer. Even fusion's most ardent supporters admit it will be several decades before the technology becomes commercial. But if the physics comes to fruition, it could be very big—just as the oil runs out and climate change accelerates.

In May, the governments of the EU, the US, China, India, Japan, Russia and Korea initialled a treaty to build the International Thermonuclear Experimental Reactor (ITER), the world's largest fusion machine, in a forest at Cadarache in Provence. They will sign formally in November. Half of the money will come from the EU. ITER will take a decade to build and will then run for two further decades, performing tens of thousands of fusion experiments. At the end of that time, say its backers, the world will know once and for all if nuclear fusion has a viable future. Technically viable, that is. The economics will come later.

"This is the most significant science treaty ever signed, the world's biggest scientific collaboration," said Janez Potoc?nik, EU commissioner for science and research, at the initialling ceremony in Brussels. Britain's top fusion administrator, Chris Llewellyn Smith, smiled in the background. A tall, white-haired physicist and knight of the realm, he is director of the world's largest existing reactor, in the village of Culham in Oxfordshire. He says simply: "This project is of huge significance. It could lift billions out of poverty," by providing them with cheap electricity for the first time.

Not everyone is so sure. Greens dismiss the project as a "dangerous toy" and a waste of money that could be paying for thousands of wind farms. Even among physicists not everyone thinks that fusion has a future. Embarrassingly, shortly before the Brussels ceremony, America's leading research journal Science published the posthumous testament of one of fusion's pioneers, William Parkins, who concluded that "the history of this dream is as expensive as it is discouraging." The US alone, Parkins said, had spent $20bn on the fusion quest over 50 years, without result. It was time to write off the venture. The journal's editor publicly backed the conclusion. As of May, the world is engaged in a game of double or quits to prove them wrong.


How does fusion work?

To see fusion in action, go to Culham in Oxfordshire. As well as being the largest, the fusion reactor known as JET (Joint European Torus) is, by common consent, the world's most successful. It is the prototype for the ITER machine, standing 20 metres high and surrounded by an acre of equipment on the site of the British Atomic Energy Authority.

It cost €1bn to build and so far, over its 23-year life, has cost another €1bn to run. It has at times soaked up half of Britain's entire government budget for energy research.

The reactor is constantly doing experiments into the more abstruse physics of how to make fusion happen, how to control it and how to do it better. Its greatest moment came in 1997 when, for a fraction of a second, the reactor produced 16.1 megawatts of electricity, which is still a world record. Headlines went round the world, though few mentioned that it took 25 megawatts to heat the reactor, and even more to run the other bits needed to keep it going, just for that fraction of a second.

The fact is that the Culham reactor, far from producing power, is by some way Britain's biggest single electricity user. During a typical experiment, of a kind undertaken several times a night and some 66,000 times in its history, the plant briefly consumes up to 2 per cent of all the electricity capacity available in the country. Its proximity to Didcot power station is probably no coincidence.

So what happens inside this extraordinary machine? Superficially it is a gas-burning boiler. But it is a boiler that requires only a tiny amount of nuclear fuel—about a gram at any one time—to generate vast amounts of energy. The fuel is made up of two isotopes of hydrogen, known as deuterium and tritium. The former is extracted from ordinary water. The latter, which is mildly radioactive, can be collected from the waste streams of some nuclear fission reactors, manufactured from lithium, a relatively common metal, or generated inside the fusion reactor itself. The purpose of the reactor is to burn these two isotopes at super-high temperatures, generated by the world's hottest microwave oven. Heated enough, they form a plasma—a superheated gas—and fuse together. When that happens, they create another element, helium, plus large amounts of energy.

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Old 07-13-2006, 09:02 PM
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In practice, it's not that simple. Fine-tuning how it is done has become a life's work for some of the world's best minds. And even now, after 50 years of experiments, researchers have still never generated more energy than they need to fire up the microwave oven.

One problem is that, while deuterium and tritium fuse more easily than any other atoms, to make the reactions happen on earth still requires temperatures of 100m degrees Celsius. That is ten times hotter than the sun, which has huge gravitational fields allowing fusion to occur more easily. Another difficulty is that to maintain that temperature and sustain the fusion reactions, it is necessary to prevent the hot plasma from hitting the reactor wall, which will slow and cool everything down. This is done by making the reactor doughnut-shaped, so the plasma can flow endlessly round, and by installing the world's most powerful magnets to maintain a magnetic field 10,000 times stronger than the earth's.

This basic design, called a Tokamak, is a Russian invention—developed in the 1950s by Andrei Sakharov, the dissident and father of the Russian H-bomb. But his machines were small. As scientists have built larger ones, they have found that Sakharov's simple presumptions about how plasmas work break down. Instabilities break out in the plasma—like solar flares round the sun—that no computer can predict. Hence the large number of experiments, whose purpose, says Llewellyn Smith, is "to learn how to control the hot gas."

ITER is the next step up in size—twice as high and with ten times the volume of Culham. That means it should, at last, allow fusion researchers to generate more energy than they consume. Ten times more, according to How, who wrote the design specs. "It's like a teapot," he says, "the bigger it is, the better it retains heat." But the extra size may also create new problems in the operation of the plasma.

The instabilities in the plasma are not the only problem. In this world of extremes, some of the most pressing questions concern what the reactor should be made from. What kind of materials can best withstand the huge forces being placed on them inside the reactor: temperature gradients that some believe are greater than any in the universe; shock waves from hundreds of megawatts of energy travelling at a fifth of the speed of light; and magnetic fields 10,000 times greater than any experienced on earth?

"No one has ever subjected materials to these conditions," says Llewellyn Smith. Most believe that if the project fails it will be because of the engineering of materials rather than failures of basic physics.

These extreme conditions mean that JET can only create its super-high temperatures for 30-40 seconds before the whole apparatus has to be cooled down to prevent it shattering. ITER will have magnets cooled close to a temperature of absolute zero, because at those temperatures they become "super-conducting," and don't heat up so much. Researchers hope to be able to run it for half an hour or so at a time. But even that will not be anything like enough for commercial reactors.

That is why, in parallel with ITER, another international agreement will fund a $1bn research centre in Japan, where new materials that can stand the extremes of a commercial reactor will be developed. Hopefully.

And if all goes, well, the technology could head in other interesting directions. A recent proposal would not connect fusion reactors to electricity grids, but rather use them to provide the large amounts of energy needed to manufacture hydrogen fuel for shipping round the world. This "fusion island" proposal could kickstart the much-discussed "hydrogen economy."

All this has been a long journey. ITER was first proposed as a successor to JET back in the mid-1980s, as part of efforts to thaw the cold war through science. Mikhail Gorbachev and Ronald Reagan agreed on a joint project to develop fusion power for the world. But through the 1990s, with oil prices low, Russia in economic free fall and interest in all things nuclear undermined by Chernobyl, governments backed off investment in fusion.

The US pulled out of the ITER project altogether in 1998, citing worrying scientific research that suggested turbulence inside the plasma would prevent fusion ever being generated for long periods. Since then, new research suggested the turbulence problems had been exaggerated, and the US rejoined the project in 2003. But William Parkins is not alone in claiming that nobody yet has answers to a series of technical conundrums: how to remove heat efficiently from the reactor vessel; and what, if any, materials would stop the vessel becoming either brittle or leaky. Nor is he alone in suggesting that there may be no answers. The physics may be good, he said, but the engineering will probably never work.

Publicly, the physicists say the science is all over bar the shouting. But one senior researcher at ITER may have given the game away when he told a room full of journalists in May: "We think it's going to work. We have to, or the politicians wouldn't give us the money."

What are we to make of this? One respected commentator has said that there may be a 20 per cent chance of the world getting 20 per cent of its electricity from fusion by 2100. Llewellyn Smith, while thinking the chances are rather better than that, says that even such long odds would represent a worthwhile gamble for the world, notwithstanding the opportunity costs. The director of the science office at the US department of energy, Raymond Orbach, says: "We think that fusion will, by the end of the century, be producing 40 per cent of the electricity produced in the world today," which would represent about 15 per cent of the total electricity demand in 2100.

But that is a long way off. There are several big steps along the way. If ITER, over the next 30 to 40 years, fails to demonstrate that fusion can generate an order of magnitude more power than it uses, then the whole programme, which by then will be almost a century old, will finally have to be abandoned. And the tens of billions of dollars spent on it blamed on overambitious physicists.

John How is familiar with the long history of delays to fusion research, and he smiles grimly at a ritual re-telling of the old industry joke: commercial fusion power is 40 years away, and always has been. "I've been in this for 40 years," he says. "The current timetable is very, very ambitious. I'd say commercially viable fusion energy is 100 years away still."

Maybe so. But the dream is alive again. And the fusion gypsies are back on the road and headed for the south of France.


Is it safe?

Unlike fission, fusion is intrinsically safe, say its promoters. There are no runaway reactions and only minimal radioactive waste. There are, it is true, health and safety issues for workers. At Culham, everybody is cleared out of the main building containing the reactor during actual operations, because radioactivity does invade the sealed area, though it decays quickly. At ITER, where the radioactivity will be higher, the plan is that only robots will go in. But if anything goes wrong in the reactor, the reactions simply stop within a few seconds.

After the machine is dismantled, some of its scrap metal will be radioactive. The design aim is to ensure this has decayed to safe levels within 100 years, so there are no long-term disposal issues; engineers seem confident this can be done. The main radioactive ingredient, tritium, is used only in small quantities and has a half-life of 12 years.

Is there a doomsday scenario? "If you flew a plane into the JET reactor, the worst that would happen is the release of about a gram of tritium," says Llewellyn Smith—though there is another 20 grams on site. In Provence they say that the worst possible accident might lead to the local village being evacuated for a few years.
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Old 07-14-2006, 04:57 AM
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I read about one fusion plant once that took the equivalent energy to power a city of 70,000 to get it up and running.

It's a delicious fantasy but you have to wonder if it might just beyond the realm of the possible.

Good news is we already have fusion power!! It comes to us in regular doses and the reaction takes place at a safe distance of 93 million miles. Of course, GS's post that started the thread is not encouraging in that regard.

Anywho, my dream project involves a smaller version of this type of parabolic trough mirror plant:





The Lutz corp. made 9 plants like these in SoCal, I'm sure these are photos of one of those plants. Mucho info on that here.

The mirrors on these are state of the art and a bit expensive. That's why it hasn't taken off yet. I'm thinking a much smaller size, about 1 or 2 acres, for a community. No need for an expensive network grid that way. According to the specs in the link above, the Lutz plants were able to generate between 120 and 170 watts per meter of mirror.

For a one acre plant, with half of the area mirror and the other half corridor space, needed for maintenance and cleaning of course, you'd get 242 Kw at the lower rate and 344 Kw at the higher rate. I'm thinking of a slightly cruder mirror design, should be quite a bit cheaper and easier to build away from the First World (long story on the design), and with the disadvantage of economies of scale, you could possibly get 150 Kw from a one acre plant, and that's not bad.

Of course it's only in the daytime and many places would not do so well in the winter. Some of the heat could be used for absorption type refrigeration (propane or NG refrigerator type principal) that could be used for air conditioning in the hottest months, when sun to power the device would be the most abundant.

One fantasy is to be able to throw a one or two acre plant up quickly in remote, third world settings, and use the power for refrigeration of medicines (a biggie in remote settings), making of ice for food preseration, and purification of water. Some people, such as in the Gates Foundation are desirous of being able to refrigerate medicines in third world settings.

A plant like this would be virtually silent, would not be unsightly like a windmill, and could be on or near site. The elec. gen. plant could use heat from other sources for a small amount of power at night. In fact, I believe most or all of the Lutz plants are hybrid -- using nat. gas at night to maximize the return on investment in the generating system.
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Old 07-14-2006, 11:37 AM
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I think we should start a protest movement on this issue.

It can parallel the very successful one I have going to protest plate tectonics.
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Old 07-14-2006, 11:47 AM
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So does that mean sun bathing with Crisco is safe again?
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Old 07-14-2006, 12:07 PM
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Quote:
Originally Posted by GermanStar
New research shows that much less sunlight is reaching the earth than 50 years ago. "Global dimming", as it has inevitably become called, has been suspected for nearly 20 years, since a Swiss geography researcher, routinely checking sunshine levels across Europe in 1985, found that they had dropped, even on the brightest days. Studies all around the world found similar results, showing drops in sunlight ranging from 2 to 37 per cent since the 1950s.

The research, published in Science, is the first to prove that the dimming is a global phenomenon. Scientists at the New Jersey and California Institutes of Technology remembered how Leonardo da Vinci had worked out that the dark side of the moon was illuminated by sunlight reflected from the Earth. By measuring this "Earthshine" they worked out that the world is about 10 per cent darker than half a century ago.

Scientists are divided over whether global dimming is a natural phenomenon or caused by pollution, such as soot particles emitted from car exhausts, and global warming, which evaporates more water from the Earth, causing more clouds. Professor Philip R Goode, who led the study, told The Independent on Sunday that the way the dimming has varied suggests that it may be a natural phenomenon.

Nova recently had a show on global dimming. They stated that the amount of sunlight that reaches the earth has been reduced by between 9% and ~30%depending on where measured. They used a number of techniques to identify the causes and results of this phenomena. While there are a number of issues related to this phenomena, the primary causes revolve around the fact that dust particles are the seed stock around which clouds form. The more dust the more clouds. The more clouds the more reduction of sun light. Since a goal of most nations is to reduce the amount of dust particles being pumped into the air, the authors of the show claim that were we to remove many of elements causing global dimming, the end result would be a drastic and sudden increase in the effects of global warming. http://www.pbs.org/wgbh/nova/sun/dimming.html
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