首页
登录
职称英语
Something very unusual happened about 80,000 years ago, as Earth’s last ice
Something very unusual happened about 80,000 years ago, as Earth’s last ice
游客
2023-08-25
15
管理
问题
Something very unusual happened about 80,000 years ago, as Earth’s last ice age was getting started. Sea levels that had been dropping for thousands of years—as more and more water became trapped in expanding glaciers(冰川)—suddenly rose, according to a new study. Then after a few thousand years, the levels fell again. Although the researchers haven’t found the cause of this phenomenon, they say the findings could force at least a partial rethinking of the mechanisms governing Earth’s climate.
For the past several hundred thousand years, our planet seems to have followed a fairly regular climate cycle. About every 100,000 years, kilometers-thick ice sheets form atop the northernmost reaches of North America, Europe, and Asia and extend well into the mid-latitudes. The ice sheets also tie up so much seawater that ocean levels can drop by over 100 meters. Then, after about 90,000 years, the glaciers retreat and land reappears, until the next ice age begins. The last ice age ended about 11,000 years ago.
Various researchers going back nearly a century have attempted to isolate the cause of the ice-age cycle. They have uncovered several factors —periodic changes in Earth’s orbit around the sun, for example—that seem to be in play. But so far no one has presented the definitive answer.
In the recently published Science, a team doesn’t so much solve the puzzle as reinforce the uncertainties about how the ice-age cycle behaves. What they’ve found is very strong evidence that when Earth should have been preparing for the last ice age, the seas rose.
The researchers found that sea level 80,000 years ago had rebounded to the point where it rose 1 meter higher than it is today. And it could have risen quite quickly, as much as 2 meters per century, says geochemist Jeffrey Dorale of the University of Iowa.
That suggests the glaciers were melting at a tremendous rate. Even half that rate would still be "a major finding," Dorale says. So it "has major implications for future concerns with sea-level change."
The study "shows persuasive evidence" for a surge in sea level about 80,000 years ago, says geologist Daniel Muhs of the U.S. Geological Survey in Denver. He says the findings help make a "powerful" argument for the phenomenon. Still mysterious, however, are other data, taken from Barbados and New Guinea, that also suggest rising sea level about 80,000 years ago but not nearly as much of a change. It means, Muhs says, "that there is much about interpreting the geologic(地质学的)record of sea-level variation that we still do not understand." [br] According to Daniel Muhs, data taken from Barbados and New Guinea suggested that the sea level______.
选项
A、remained unchanged
B、didn’t rise much
C、rose remarkably fast
D、rose mysteriously
答案
B
解析
倒数第2句中的however和not nearly as much of a change都表明这两个地方的海平面上升的幅度“几乎不能算是变化”,即巴巴多斯和新几内亚获取的数据应显示海平面上升的幅度不大,本题应选B。
转载请注明原文地址:https://tihaiku.com/zcyy/2955652.html
相关试题推荐
[originaltext]Job-huntingissomethingthatyouprobablyhavedoneorwill
[originaltext]Job-huntingissomethingthatyouprobablyhavedoneorwill
[originaltext]Todaywhenamanstepsontothemoon,orsomethingnewandim
[originaltext]Todaywhenamanstepsontothemoon,orsomethingnewandim
[originaltext]Todaywhenamanstepsontothemoon,orsomethingnewandim
[originaltext]W:TodayIthoughtwewouldtalkaboutsomethingbrightandcheer
[originaltext]W:Whatonearthhashappenedtoyou?Youlookabsolutelywornou
[originaltext]W:Whatonearthhashappenedtoyou?Youlookabsolutelywornou
[originaltext]W:Whatonearthhashappenedtoyou?Youlookabsolutelywornou
[originaltext]W:Whatonearthhashappenedtoyou?Youlookabsolutelywornou
随机试题
Shewantedtoknow______childitwasonthegrass.A、thatB、whoseC、whatD、whom
采用虹吸筒法测定土的比重时,已知干土质量为1965g,水的比重为0.999,晾干
关于商业银行压力测试,下列表述错误的是()。A.压力测试情景越极端,压力测
下列哪项不是高血压病的并发症A.短暂性脑缺血发作 B.脑血栓形成 C.脑出血
下列关于道德与法律的区别,说法不正确的是()。A.调整手段不同 B.表现
野生药材资源保护管理条例将受保护的野生药材资源分为A.四级管理 B.三级管理
A. B. C. D.
某房地产投资项目的名义利率为15%,试计算按月复利和按季度复利的有效年利率各为(
有关手术中的解剖分离,哪种说法是错误的A.术者应熟悉局部解剖,具有明确的解剖概念
某种钢材,其塑性和韧性较高,可通过热处理强化,多用于制作较重要的、荷载较大的机械
最新回复
(
0
)