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  3. A Cooler Planet Scientists are cooking up solutions based on current technology that they say they could dramatically turn do

A Cooler Planet Scientists are cooking up solutions based on current technology that they say they could dramatically turn do

admin2010-03-22  12
问题                            A Cooler Planet
   Scientists are cooking up solutions based on current technology that they say they could dramatically turn down the heat of global warming over the next 50 years.
   Innovations such as cheaper wind power, gas-electric hybrid and gas cards that generate funds for climate-change projects already are available. Introducing them across the nation could put a dent in the growth of greenhouse gases that are warming the planet, scientists say.
   The concentration of carbon dioxide--a potent greenhouse gas--is likely to double before the end of the century, the United States says. Scientists say further warming is inevitable as greenhouse gas emissions climb but that the worse effects can still be avoided.
   "The question now is not ’whether to adapt?’ but ’how to adapt?’" says a 2004 U.N. report on climate change.
   The solutions, says experts, must come from action by politicians, business people, scientists and individuals. Over the next century, power could be derived from sources that release less carbon dioxide into the atmosphere such as nuclear fusion, hydrogen fuel cells and more efficient combustion engines(内燃机).
Scientists: Technology already exists
   Technology is a crucial component to meeting the challenge of global warming, say climate researchers and policy experts.
   "You need technology;" says Elliot Diringer, international strategies director with the Pew Center on Global Climate Change. "There’s no question about that. The question is, ’What is the most efficient way to not only generate the technology but get it deployed.’"
   The intergovernmental Panel on Climate Change, a U.N. body issuing regular assessments on the climate, says innovation has advanced faster than expected. It estimates technological improvements could reduce greenhouse gas emissions below 2,000 levels within 20 years and avert even more risky levels of such concentrations.
   The IPCC has estimated that technological improvements could sometime between 2010 and 2020 reduce greenhouse gas emissions to levels below those in the year 2000.
   "We need to move as fast as we can," Diringer says.  "The longer we wait to take concerted action, the greater the impact will be... the more it will cost to achieve the reduction."
   Technology with the greatest potential to reduce greenhouse gas emissions already exists, says Princeton University scientists Stephen Pacala and Robert Socolow in a 2004 study published in the journal Science.
   Improving efficiency and conservations could reduce billions of tons in atmospheric emissions of greenhouse gases each year. Improvements such as efficient engineering, better gas mileage(英里里程) and new fuel sources for vehicle and power plants have the potential to halt growth of emissions by around 2050, according to the study.
   "It is important not to become diverted by the possibility of revolutionary technology," the Princeton authors write in Science.  "Humanity can solve the carbon and climate problem in the first half of this century simply by increasing we already know how to do."
   The scientists picked seven actions that they say could make the climate stable by 2054. They focused on technology already in place that simply needs to be expanded-- a lot.
   Cars are an easy target. Each gallon (加仑) of gas burned gives off about 20 pounds of carbon dioxide into the atmosphere, according to the Environmental Protection Agency. That’s a lot of carbon for the 2 billion cars that may be on the road in 2054, nearly four times the number today, the authors report.
   The Science article suggests that doubling the average fuel efficiency of cars from 30 miles per gallon today to 60, switching to wind-generated hydrogen fuels or halving the annual number of miles traveled per car to 5,000 could reduce carbon dioxide emissions. The savings would provide one-seventh of the total cuts needed to make U.S. emissions stable, the article states.
   In addition, scientists are watching plenty of other technologies being developed to make emissions stable.
Carbon storage
   Burying carbon dioxide allows fossil fuel companies to continue pumping oil while reducing greenhouse emissions. The United Nations estimates by 2050 it should be possible to store half of the increasing global emissions in underground reservoirs (水库) at reasonable prices.
   The U.S. government already has started a test project at a West Virginia coal power plant. The energy company BP sends 1 million tons of carbon dioxide each year beneath the sands of Sahara desert at one of its facilities in Algeria.
   These carbon-reducing projects send millions of tons of carbon dioxide gas into underground geologic formations such as gas beds now filled with water, natural gas or oil.
   The risks of such techniques include leakage of carbon dioxide from underground reservoirs that may endanger human life and environment. Scientists are studying techniques to find which rock formations permanently store gases such as carbon dioxide.
Renewable energy
   Renewable power is a major facet of reducing global warming emissions, according to the United Nations.
   Because most renewable energy sources--wind, ocean tides, solar, biomass fuel--emit less carbon dioxide into the atmosphere than they absorb, they do not add to climate change. The share of renewable in the world energy supply accounts for at least 14 percent of the total, the United Nations estimates.
   The price of these renewable fuels and technology is plummeting as demand grows and hardware improves. "Green" tariffs, already introduced in some European countries, guarantee premium prices for energy derived from renewable sources.
   States such as New York and California also require utilities to generate a fraction of their energy supply from renewable.
Trading carbon
   Carbon emissions trading is designed to make global warming prevention affordable, according to the U.N. Convention on Climate Change.
   Under the Kyoto Agreement, participating countries agree to emit a certain amount of carbon. If a country cannot afford to meet its carbon emissions limit, it can buy "credits" from a country that has produced less than its allotted amount.
   Although critics say there are significant problems under the Kyoto system, the United Nations says emissions trading allows countries gradually to eliminate carbon dioxide while preventing some economic hardships of reducing emissions growth.
Corporate action
   Companies also an: devising ways for business and individuals to offset greenhouse emissions. Oregon-based Climate Neutral Network says it soon will offer air travelers access to "Cool Class" air travel in which a portion of airline fares, negotiated through contracts with different companies, are invested in ways to reduce greenhouse emissions.
According to the United Nations about ________________ of the total world energy supply goes to the renewable energy.
选项
答案14 percent
解析 由题干中的关键词die United Nations，renewable energy定位到小标题 Renewable energy下面第二段末句：The share of renewable in the world energy supply accounts for at least 14 percent of the total，the United Nations estimates，由此得出答案。
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