VOA标准英语2012--Ice Age Melt Offers Future Climate Clues
时间:2019-01-13 作者:英语课 分类:VOA标准英语2012年(八月)
Ice Age Melt Offers Future Climate Clues
University of Wisconsin geologist 1 Anders Carlson studies ice sheet melt from land and ocean sediment 2 cores. His study describes what prehistoric 3 Earth was like in North America and Northern Europe some 140,000 years ago.
“What we found in this paper was that ice that’s resting on land it responded very quickly to the warming climate, but then it didn’t retreat really rapidly. It kind of chugged along and slowly melted like an ice cube if you put a hair dryer 4 on it,” Carlson says, adding that was not the case with ice sheets floating on the ocean. “Marine 5 based ice sheets behave unpredictably. They may not do anything for a while, and then they all of a sudden respond very abruptly 7. They can rapidly disappear.”
Greenland and Antarctica hold the Earth’s last remaining ice sheets. In July, satellite data showed that 97 percent of the surface of the Greenland ice sheet had turned to slush over four days, a rate faster than at any time in recorded history. According to Carlson, it might be responding rapidly to small changes in temperature, similar to what he saw in the prehistoric record of ice sheets on land.
“But that said, they haven’t catastrophically collapsed 8 in the past either to rapidly raise sea level in the time scale that humans would care about, that we would be hard pressed to adapt to.” Carlson says the Antarctic marine-based ice sheet is less predictable. “What this would say from the past is that these ice sheets, well they may not do anything for a bit. But then if you want to catastrophically raise sea level like on the orders of a meter or two in human lifetime, there is prehistoric precedent 9 for that happening.”
A second paper in Nature Geoscience looks back 12,000 to 7,000 years to when massive ice sheets still covered the high latitudes 10 of the Northern Hemisphere. At that time, the global climate was roughly comparable to what it is today and glaciers 11 were melting.
The study describes abrupt 6 sea level jumps - from one-half to two meters - from melting glaciers.
"What happens when you suddenly drain these massive amounts of fresh water into the ocean? It’s going to change ocean circulation,” says co-author Torbjorn Tornqvist, an Earth scientist at Tulane University in Louisiana.
Today, rapid melting from the Greenland ice sheet would send massive amounts of fresh water into the North Atlantic Ocean, changing the marine environment.
“But it will also lead to potentially higher precipitation rates in the same region, which could also lead to fresher surface waters in the North Atlantic," Tornqvist says. "So we need to understand whether those types of changes could potentially be capable of triggering these kinds of abrupt climate events.”
Tornqvist adds that understanding how abrupt climate changes affect Earth’s geologic 12 past can help design climate models that can better predict the future.
- The geologist found many uncovered fossils in the valley.在那山谷里,地质学家发现了许多裸露的化石。
- He was a geologist,rated by his cronies as the best in the business.他是一位地质学家,被他的老朋友们看做是这门行当中最好的一位。
- The sediment settled and the water was clear.杂质沉淀后,水变清了。
- Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。
- They have found prehistoric remains.他们发现了史前遗迹。
- It was rather like an exhibition of prehistoric electronic equipment.这儿倒像是在展览古老的电子设备。
- He bought a dryer yesterday.他昨天买了一台干燥机。
- There is a washer and a dryer in the basement.地下室里有洗衣机和烘干机。
- Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
- When the war broke out,he volunteered for the Marine Corps.战争爆发时,他自愿参加了海军陆战队。
- The river takes an abrupt bend to the west.这河突然向西转弯。
- His abrupt reply hurt our feelings.他粗鲁的回答伤了我们的感情。
- He gestured abruptly for Virginia to get in the car.他粗鲁地示意弗吉尼亚上车。
- I was abruptly notified that a half-hour speech was expected of me.我突然被通知要讲半个小时的话。
- Jack collapsed in agony on the floor. 杰克十分痛苦地瘫倒在地板上。
- The roof collapsed under the weight of snow. 房顶在雪的重压下突然坍塌下来。
- Is there a precedent for what you want me to do?你要我做的事有前例可援吗?
- This is a wonderful achievement without precedent in Chinese history.这是中国历史上亘古未有的奇绩。
- Latitudes are the lines that go from east to west. 纬线是从东到西的线。
- It was the brief Indian Summer of the high latitudes. 这是高纬度地方的那种短暂的晚秋。
- Glaciers gouged out valleys from the hills. 冰川把丘陵地带冲出一条条山谷。
- It has ice and snow glaciers, rainforests and beautiful mountains. 既有冰川,又有雨林和秀丽的山峰。 来自英语晨读30分(高一)