Passage One
Researchers said it was clear that the world’s oceans play a major role in queuing up rapid climate changes, but that thus far the mechanics (机制，结构) of such changes were poorly under stood.
"It’s like being blindfolded and walking toward the edge of a cliff," said Wallace Brocker, a professor of environmental sciences at Columbia University. "We don’t understand (the factors) so we don’t really know what to look for."
Using ice cores drilled from glaciers and other ice sheets, the researchers have developed a model showing world temperatures’ rising and falling with unsettling frequency over the past110 000 years.
While some of the changes have been slow and steady, such as the end of the last Ice Age some 12 000 years ago, others have been swift and unexpected, such as the rapid warming of the North Atlantic from 1920 to 1930 and the Dust Bowl drought of the 1930s.
The most drastic temperature changes—believed to be as much as 18 degrees Fahrenheit over the space of just a few years—exceed any recorded in human history, they said．This was not in tended to alarm the public, but that they hoped it would stimulate policy makers to prepare for the possibility of rapid temperature flux.
Greenhouse gases, emitted by fossil fuels such as oil and coal, have been linked by many re searchers to a rise in global temperatures. A 1997 Kyoto Treaty on global warming sought to cut emissions of such gasses by developed nations, but the Bush administration this year spurned (轻蔑或傲慢地拒绝) the treaty, saying pollution controls would be too costly for the U.S. economy.
The NAS panel called for research to identify what it described as "no-regrets" measures that would cost relatively little and would be good policies regardless of the extent of environmental change.
Such measures could include regulations to reduce damage to water, air and land, or slow climate change, or helping societies cope with abrupt climate changes by developing new financial instruments such as weather derivatives (衍生证券) and catastrophe bonds to reflect the risks.
Societies have faced both gradual and abrupt climate changes for millennial and have learned to adapt through various mechanisms, such as moving indoors, developing irrigation for crops, and migrating away from inhospitable (不适宜居住的) regions. It is important not to be fatalistic (宿命论的) about the threats posed by abrupt climate changes. |
According to the passage, over the past 110 000 years, world temperature .
A．has been keeping rising
B．has risen and fallen at regular intervals
C．has experienced no rapid and sudden changes
D．has experienced both smooth and abrupt changes