Practicability of Geoengineering Triggers Hot Discussion
The Five Large Geoengineering Projects
Stratospheric Aerosol
Late in the afternoon on April 2, 1991, Mt. Pinatubo, a volcano on the Philippine island of Luzon, began to rumble with a series of the powerful steam explosions that typically precede an eruption. Pinatubo had been dormant for more than four centuries, and in the volcanological world the mountain had become little more than a footnote. The tremors continued in a steady crescendo for the next two months, until June 15th, when the mountain exploded with enough force to expel molten lava at the speed of six hundred miles an hour. The lava flooded a 250-square-mile area, requiring the evacuation of two hundred thousand people.
Within hours, the plume of gas and ash had penetrated the stratosphere, eventually reaching an altitude of twenty-one miles. Three weeks later, an aerosol cloud had encircled the earth, and it remained for nearly two years. Twenty million metric tons of sulfur dioxide mixed with droplets of water, creating a kind of gaseous mirror, which reflected solar rays back into the sky. Throughout 1992 and 1993, the amount of sunlight that reached the surface of the earth was reduced by more than ten per cent.
The heavy industrial activity of the previous hundred years had caused the earth's climate to warm by roughly three-quarters of a degree Celsius, helping to make the twentieth century the hottest in at least a thousand years. The eruption of Mt. Pinatubo, however, reduced global temperatures by nearly that much in a single year. It also disrupted patterns of precipitation throughout the planet. It is believed to have influenced events as varied as floods along the Mississippi River in 1993 and, later that year, the drought that devastated the African Sahel. Most people considered the eruption a calamity.
Drawback：Although it will be one of the fastest ways to hinder global warming, it is also the most dangerous one. Once started, it will have tremendous impact on global climate model.
Practicability: 50%.
Space Mirror
An Astronomer said that, by installing a huge glass sunshade in the sky and then sending it to the orbit will reflect smart part of sunlight. He believed that, 2% reduction of sunlight arriving on the Earth would hinder the trend of global warming.
Drawback: the main threaten faced by this mirror comes from asteroids. The glass disk can be broken easily by space debris. What's more, the maintaining of the "space shade" needs time, experience and money.
Practicability: 40%.
Ocean Fertilization
To cope with climate warming, some suggested to put large numbers of iron fertilizer in the sea area growing phytoplankton. Iron fertilizer will promote phytoplankton's growth, enhancing the ability of absorbing the carbon dioxide.
Drawback: Such method will not only be time-consuming and have little effect, but also cause fatal impact on marine life.
Practicability: 20%.
Artificial Trees
US researchers put forward the concept of artificial trees while discussing the solution of global warming. The machine will use common elements like iron, copper, aluminum, silicon and carbon as raw materials, and be powered by solar energy to complete self-reproduction. The carbon dioxide extracted by this machine will be 1000 times larger than that of a common tree.
Drawback: Experts noted that, no one will suspect the feasibility of this plan, but at present, we still fail to figure out how much it will cost.
Practicability: 60%.
Artificial Afforestation
Artificial afforestation can not only beautify the environment, but also gain favor from those who believe that "remould climate" is a crazy idea. Painting the rooftop into white color or coating the deserts with reflecting materials may also block the undesirable radiation "out of the door".
Drawback: Geo-engineers believe, only depending on these methods can not avoid the ill consequence of climate changes.
Practicability: 10%.
sources：[http://en.twwtn.com/Bignews/?ID=51165]
Stratospheric Aerosol
Late in the afternoon on April 2, 1991, Mt. Pinatubo, a volcano on the Philippine island of Luzon, began to rumble with a series of the powerful steam explosions that typically precede an eruption. Pinatubo had been dormant for more than four centuries, and in the volcanological world the mountain had become little more than a footnote. The tremors continued in a steady crescendo for the next two months, until June 15th, when the mountain exploded with enough force to expel molten lava at the speed of six hundred miles an hour. The lava flooded a 250-square-mile area, requiring the evacuation of two hundred thousand people.
Within hours, the plume of gas and ash had penetrated the stratosphere, eventually reaching an altitude of twenty-one miles. Three weeks later, an aerosol cloud had encircled the earth, and it remained for nearly two years. Twenty million metric tons of sulfur dioxide mixed with droplets of water, creating a kind of gaseous mirror, which reflected solar rays back into the sky. Throughout 1992 and 1993, the amount of sunlight that reached the surface of the earth was reduced by more than ten per cent.
The heavy industrial activity of the previous hundred years had caused the earth's climate to warm by roughly three-quarters of a degree Celsius, helping to make the twentieth century the hottest in at least a thousand years. The eruption of Mt. Pinatubo, however, reduced global temperatures by nearly that much in a single year. It also disrupted patterns of precipitation throughout the planet. It is believed to have influenced events as varied as floods along the Mississippi River in 1993 and, later that year, the drought that devastated the African Sahel. Most people considered the eruption a calamity.
Drawback：Although it will be one of the fastest ways to hinder global warming, it is also the most dangerous one. Once started, it will have tremendous impact on global climate model.
Practicability: 50%.
Space Mirror
An Astronomer said that, by installing a huge glass sunshade in the sky and then sending it to the orbit will reflect smart part of sunlight. He believed that, 2% reduction of sunlight arriving on the Earth would hinder the trend of global warming.
Drawback: the main threaten faced by this mirror comes from asteroids. The glass disk can be broken easily by space debris. What's more, the maintaining of the "space shade" needs time, experience and money.
Practicability: 40%.
Ocean Fertilization
To cope with climate warming, some suggested to put large numbers of iron fertilizer in the sea area growing phytoplankton. Iron fertilizer will promote phytoplankton's growth, enhancing the ability of absorbing the carbon dioxide.
Drawback: Such method will not only be time-consuming and have little effect, but also cause fatal impact on marine life.
Practicability: 20%.
Artificial Trees
US researchers put forward the concept of artificial trees while discussing the solution of global warming. The machine will use common elements like iron, copper, aluminum, silicon and carbon as raw materials, and be powered by solar energy to complete self-reproduction. The carbon dioxide extracted by this machine will be 1000 times larger than that of a common tree.
Drawback: Experts noted that, no one will suspect the feasibility of this plan, but at present, we still fail to figure out how much it will cost.
Practicability: 60%.
Artificial Afforestation
Artificial afforestation can not only beautify the environment, but also gain favor from those who believe that "remould climate" is a crazy idea. Painting the rooftop into white color or coating the deserts with reflecting materials may also block the undesirable radiation "out of the door".
Drawback: Geo-engineers believe, only depending on these methods can not avoid the ill consequence of climate changes.
Practicability: 10%.
sources：[http://en.twwtn.com/Bignews/?ID=51165]
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