分类： IT职场
2009-02-19 22:33:28
Robert Holeare devoted to the study of marine science and global climate of freedom of science writers. His book Drawing deep map: the extraordinary story of ocean science (Mapping the Deep: The Extraordinary Story of Ocean Science) won AI in 2001 Cervantes Prize for Science Books. He recently published with Wallace S Bullock (Wallace S. Broecker) co-author of deal with climate issues: climate change over the past revealed by the current threats, as well as coping strategies (Fixing Climate: What Past Climate Changes Reveal about the Current Threat-and How to Counter It). He often travel in the United States Alabama between Birmingham and Dijon, France.
Subsequent decades, the use of the Earth climate engineering mind has always existed, but these ideas constantly marginalized - scientists and environmentalists generally agreed that the Earth is based on engineering ideas seem foolish and even immoral attempts to avoid the emphasis on global change Warm the root of the problem. Recent progress in the three engineering earth again returning to the mainstream mind.
First of all, despite years of discussions and international negotiations, until 2007, carbon dioxide emissions rose faster than the Intergovernmental Panel on Climate Change (Intergovernmental Panel on Climate Change, IPCC) is expected but also much of the worst cases. Stanford, California City, the Carnegie Science Institute of climate modeling expertdera (Ken Caldeira) pointed out: carbon dioxide emissions increasing, this trend is rising - dependence on coal in any time has not been reduced.
Secondly, melting of polar glaciers faster than almost any time in history, revealing the climate change may already be close to people can not imagine the danger of the edge - that is commonly referred to as the critical point.
Finally, the Netherlands J renowned atmospheric chemist Paul Crutzen (Paul J. Crutzen) 2006 in Climate Change (Climatic Change) journal published an article. Text, with a heavy heart, he urges people to seriously consider the Earth Engineering. In 1995, Crutzen about atmospheric ozone depletion due to research work and received the Nobel Prize in Chemistry. If he seriously consider engineering the Earth, then it seems that everyone should do so.
November 2007, Keith and the United States at Harvard University geophysicist Daniel P Schlager (Daniel P. Schrag) easily persuaded leading climate scientists, the United States go in Cambridge, Massachusetts, a group of enthusiasts take part in the Earth of Engineers discussion group. They unanimously agreed on the need for further study engineering the Earth - the Earth because some people are really, they were interested in engineering, while others are right to think only of two evils evils, there are some who wish to be achieved at once . However, they reached a consensus - the earth engineering comeback.
The Earth is divided into two types of engineering programs, you can imagine they are the equivalent of regulating the temperature of the Earth two knob. A knob to control how much light - that is, to control how much solar energy, to be more precise control of solar energy reaching the earth's surface each; another knob to control heat loss to space depends largely on atmospheric carbon dioxide content. Will remove carbon dioxide from the atmosphere, for example, to the ocean of fertilization, you can Live the root of the problem, but this practice will have to wait decades to play a greater effectiveness. Comparatively speaking, a parasol can slow down global warming - although they must continue to maintain in order to maintain the role of the sun. Therefore, the parasols of the mind can deal with those who are scientists of extreme emergency as the climate issue. Schlager said: If the Greenland ice sheet collapse is set to begin tomorrow, and you are the President of the United States, how do you do? You will have no choice.
So far, for any one way or the potential for these methods, but the existence of unforeseen negative impacts of the study also rare. Caldeira said: It said than done many, the majority of study also remain at the amateur level. Some ideas have little research value - for example, in the oceans on a large area spreading reflex particles, these particles will be inevitable reflection marine pollution, and will soon be washed up on the beach. But other ideas are worth considering.
The Earth behind the basic principles of engineering are more difficult to be ignored. Now, not many researchers suggested that blocking the sun is rising atmospheric carbon dioxide to prevent an alternative to, or engineering on the earth alone can solve the problem of carbon dioxide. Instead, scientists think, the Earth Engineering can win some time for our energy revolution, so that non-carbon energy sources to replace existing energy sources, or set up a carbon-neutral (carbon-neutral) energy consumption. The United States National Center for Atmospheric Research (National Center for Atmospheric Research, referred to as NCAR) Tom M L Wigley (Tom ML Wigley) said: I think the Earth Engineering should be taken seriously because I do not think the emissions - reduction methods on the table to talk about be able to save the Earth. no one has seriously considered such a large scale the difficulty of technical challenges.
Particles in the stratosphere
Scientists have believed that the Earth and reliable low-cost engineering methods, they proposed to the stratospheric injection of sulfur dioxide, sulfuric acid droplets forming clouds to scatter sunlight. But how much carbon dioxide in order to balance the role of the current to this point, there are still controversial.
Crutzen and Wigley are convinced that there is a option is the cheapest and most reliable method. The program as early as 1974 by Soviet physicist McHale I(Mikhail I. Budyko) at the Leningrad Geophysical Observatory said: every year millions of tons of sulfur dioxide into the stratosphere. Layer in the stratosphere, sulfur dioxide with oxygen, water and other molecular reaction, the formation of water and sulfate ions, composed of tiny droplets, attached to the dust or salt and other small molecules. Sulfuric acid droplets that form clouds can scatter sunlight, sunset will become more red, the sky will become more pale and dim, just as seriously polluted cities in the sky, as the average surface temperature would drop. In 1991, the Philippines Mount Pinatubo volcanic eruption, 20 million tons of sulfur dioxide was injected into the stratosphere. Injected into the sulfur dioxide produced all the effects described above: it makes global warming in the year, a drop of around 0.5 ℃. So, basically we know that these measures are effective, said Caldeira. In fact, the idea to write Crutzen before caldeira have been decades of simulation research.
When Crutzen regain the mind, the earth all over the world of engineering has been more fully prepared.since the article was published, the global temperature has increased by 0.5 ℃, a lot of ice has melted. 20th century 90's, the United States Lawrence Livermore National Laboratory (Lawrence Livermore National Laboratory, LLNL) Edward Teller (Edward Teller) and his colleagues proposed that the metal particles at the top can stay even longer, and can be more reflective of the sun, but insisted Crutzen Supporting stratospheric injection of sulfur dioxide to the more mature mind. This makes Crutzen plans more compelling.
Crutzen pointed out that through the burning of fossil fuels, people annually to the low-level atmospheric emissions 55 million tons of sulfur dioxide and eight billion tons of carbon dioxide. According to World Health Organization statistics, such as sulfur dioxide concentration resulted in 500,000 annual deaths. However, sulfur dioxide also declined so that the Earth temperature - although no one knows the exact value of the decline - and, thus, the Government to enforce anti-pollution laws (such as the United States Clean Air Act), but global warming makes the situation worse. Crutzen said that part of the uplift of sulfur dioxide to the stratosphere, so that sulfur dioxide will not harm us, but also that we are blocking the sun, so it is not meaningful?
preliminary idea is to allow the use of high-sulfur fuel in aircraft in stratospheric flight; Crutzen proposed balloon will be transported to the stratospheric sulfur dioxide. The current atmospheric carbon dioxide content is twice the pre-industrial, for how much carbon dioxide to balance the current role, which is also in dispute. Wigley consider necessary five million tons per year of sulfur (usually only to express the weight of sulfur); Crutzen and the United States National Center for Atmospheric Research J Russell Philip (Philip J. Rasch) calculated that if the average particle size is less than the volcanic eruption of particles (about 0.2 micron), then 1.5 million tons of sulfur required to work.
In fact, we have a lot of sulfur dioxide emissions into the lower atmosphere than all of the above estimators are much more, but the problem with the order of magnitude compared to carbon dioxide, the sulfur dioxide it is too low. Caldeira stressed that the annual volume of sulfur dioxide roughly equivalent to every American from the fire hoses inside a sulfur dioxide extrusion. Crutzen estimated that his program will cost 25 billion per year to 500 billion U.S. dollars, apportioned to the head of every citizen in developed countries is 25 ~ 50 U.S. dollars. This amount is less than the American in the lottery on the average cost, and returns to determine much more than the lottery: it is a more cool the Earth - at least the average global temperature will decline somewhat.
Troposphere of sea fog
Aerosol indirect effect is also one of the ways the Earth Engineering, with the ship will be tiny water droplets sprayed into the atmosphere over the ocean, or be able to form a layer of cumulus Zengliang have to reduce the incidence of sunshine. This method more secure, but allow a homogeneous global cooling, the new formation will be many bright cumulus layer, these problems remains unclear.
In the lower atmosphere, the role of sulfur dioxide is not just scatter sunlight and cause respiratory diseases: in the absence of cloud Office it will form a cloud, in cloud Department brighten clouds so that the original, that is, the so-called indirect effect of aerosols (aerosol indirect effect). Climate scientists think this effect has resulted in the Earth's temperature has decreased, the effect of at least scattering and aerosol particles directly, like the sun. Engine exhaust formed a straight line-shaped cloud band - track the stern (ship track) is a vivid example: they can last a few days, with the vessels extend hundreds of kilometers. Satellite photographs record their reflection of sunlight back into space.
(John Latham) for cooling the Earth's mind is, in essence, is to allow existing marine clouds become more white, methods are used stern substantial traces of these clouds Liancheng 1 - Of course, the specific measures to be more Clean green. Latham is a retired English cloud physicist, he considered unmanned fleet will be tiny droplets of seawatersky, in order to realize the idea of cooling the Earth.
Aerosol indirect effects of the basic mechanism easy enough. Cloud amount of sunlight reflected from the formation of cloud droplets depends on the specific surface area. Latham explained: For the same amount of water (from the gas condensate into droplets), the large number of small droplets than a small number of large droplets have greater surface area. Principle, adding particles to the atmosphere would lead to more formation of smaller droplets, making clouds more white, more reflective of sunlight.
Over the nearest land is full of man-made atmospheric particles, cloud particles than those that do not man-made more white, reflective capacity. Over the ocean and the atmosphere filled with mainly natural particles, including a bubble blowing waves passing to the water droplets. When the droplets arrive at around 300 meters high, the majority of water have evaporated, leaving only salt particles. But at this height, water vapor began to focus on particle re-condensation, a new droplet in the oceans over the composition of low-lying stratocumulus clouds (stratocumulus). This layer of clouds covered all over the world almost 1 / 4 of the ocean. Latham's ideas are, so that droplets of salt in the air enough to many, so that the number of cloud droplets into the original 4-fold, thereby Zengliang layer clouds over the ocean.
(Stephen Salter) are the British University of Edinburgh, Emeritus Professor of Engineering. He put forward a very innovative program - at least in theory looks innovative. Latham said: Basically it is a watering can, but the nozzle is a piece of silicon wafer, a number above one billion less than one micron in diameter hole; this watering can will be installed in a satellite-guided unmanned ship on. More precisely speaking, the ship will be a (Flettner) rotor ship, the ship equipped with a high and constantly rotating cylinder, looks like a chimney, but the result was similar to fan - Cylindrical downwind side of the mobile and the other side of the prevailing wind movement and would therefore generate uplift force.
Salt according to the design, the water flows through the vessels will lead to spin turbines for power generation, so that continuous rotating cylinder, and water from the cylinder in the exhaust, the formation of a large number of small droplets of 0.8 microns. Salter and Latham is estimated that each vessel 36 liters of seawater per second emitted, in accordance with the cost of each ship two million U.S. dollars terms, shipping a total of 1500 required three billion U.S. dollars will be offset by times of carbon dioxide caused by the issue of global warming . Exeter City in accordance with the United Kingdom Hadley Center for Climate Prediction (Met Office Hadley Center for Climate Prediction and Research) of the simulation results, only 4 percent in the deployment of marine vessels will be able to complete half the work.
However, no one on the entire extent of the Earth's temperature has been simulated uniform.said: Ultimately, when you map the temperature distribution of the world map, this map may have shaped patterns are dots, which means some very cold place, some place is very hot. Another area of concern The question is, will ship under the spray caused by wind in arid regions. Composed by many small cloud droplets can last even longer, which are very good in terms of , but this cloud would lead to reduced precipitation.
Finally, the newly formed clouds have many bright unclear. Existing climate models overestimate the effect: According to the results of these calculations, the current atmospheric aerosol should be immediately offset by the effects of global warming, it is clear that this is not true. Russell has started to Latham's ideas to create a new model. He said: We understand the climate was not many, and the aerosol indirect effect is that we understand at least a part of.
Nevertheless, on the Earth in terms of engineering programs, from the wind in the air and sprayed water on board is quite safe and sound. Latham said that if any irregularity, you can be in a few days, or up to a few weeks to stop aerial spraying of sea water - the other hand, sulfuric acid in the stratosphere can stay for several years. Wigley said: The water sprayed into the air is indeed worthy of consideration. But only to the actual inspection may know what issues there are still ideas. So far, only explore the Discovery Channel for Latham expressed their support for the ideas. Out of a series of earth works required visual effects documentary, television producers to subsidize the construction of a small boatotor.
Parasols in space
1000000000000 placed in the space of silicon nitride disk has small holes can be composed of 101,000 meters long, the umbrella group for the sun, blocking some sunlight. However, this method will spend substantial time and money.
Explore the Discovery Channel for J Roger P Angel (J. Roger P. Angel) financing and construction of a diameter of 1.3 centimeters of silicon nitride ceramic discs. This play a lot of small holes of 0.25-micron thick transparent plate, only the preservation of film thickness of 1 / 40, the hardware is much more than cling film. Angel is the University of Arizona, Stewart Observatory Laboratory Director lens is also well-known telescope lenses and optical equipment developers. Thus, the production of high performance vehicles, bearing the raw materials to produce optical devices such disc-shaped the ideas, it is in line with his identity. A few years ago, Angel's wife asked if he could do something for global warming. Angel made a reply, he re-examine an old proposal of the Earth Engineering, but ingenious ideas to transform it.
The proposal calls for the oldest of the Earth the first Lagrangian point, which is L1, the resettlement of a parasol. L1 distance from the Earth about 150 million meters in the direction of the sun's direction (in the first Lagrangian point, subject to the solar gravity and the Earth's gravity from the same size). Office is located at L1 a sunshade can be cast in the entire face of the earth the shadow of a uniform and will not pollute the atmosphere.
According to the design of Angel, which the parasol is not a spacecraft in space, but one trillion nitride disc - each disc diameter of 0.6 meters, equipped with computers and navigation systems, the total weight of not more than one grams [Angell pointed out that the black vein gold Danaidae (Monarch butterfly) body weight of less than 1 gram, but they can fly thousands of kilometers to return to breeding grounds in Mexico]. These Frisbee to every one million one group, mainly located in the ground floor through 1.6 kilometers of wire induction loop launched artillery, fired once every minute, then spend around 30 years. Angel suggested that the Earth launched parasols from the total weight should be controlled at below 20 million tons. Although the International Space Station, which is almost equivalent to the current quality of 70,000 times, but all launched into space the material is essential, there is no excess.
Efficient ion propulsion will be to bring each group of Frisbee from Earth orbit toward the L1. Where these Frisbee will be the same as licensing, the growth of 101,000 meters have been dispersed, the umbrella group for the sun. Responsible for custody of the guardian of these satellite Frisbee (Shepherd Satellite) will establish a local global positioning system, each carrying a Frisbee are a mirror as solar sails, to prevent their own groupparasols. Solar photons can be straight through each of the silicon nitride Frisbee, Frisbee can also pass through the holes in the latter than the phase-photon-photon slightly ahead of former number. This will happen in two-photon interference cancellation (interfere destructively), thus blocking part of the Earth should arrive the light, and of which around 2% of the light scattering to both sides of the Earth.
Angel is very difficult to say how his ideas seriously. He excitedly said: This is not a fast low-cost program. In fact, according to Wigley's rough estimate, a sunshade in space to spend five trillion U.S. dollars, which is impossible to realize. Caldeira said: Compared to pay such a price, the construction of wind turbines and solar equipment may be easier. Angel, I seem to have concurred with this view. Recently, he spent substantial time trying to come up with ways to concentrate sunlight to improve photoelectric conversion efficiency. After all, as he pointed out, any kind of parasols are a waste of solar energy.
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