VOA标准英语2012--Ocean Levels Rising Fast on US Coasts

 

Ocean Levels Rising Fast on US Coasts

Ocean levels are rising faster and higher on both coasts of the United States than in other parts of the globe, according to two new studies, and California could be especially hard hit.

“There will be about one meter of sea level rise by 2100," says Johns Hopkins University civil engineering professor Robert Dalrymple, chair of the academic panel that produced the report. "This is higher than what the IPCC [Intergovernmental Panel on Climate Change] had estimated.”

Melting ice from glaciers¹, ice sheets and ice caps account for 65 percent of sea level rise. Expansion of the world’s oceans as they warm makes up the rest.

California was one of three states on America’s Pacific coast - along with Oregon and Washington - to ask the National Research Council to study how changes in sea levels would affect them.

The IPCC's estimate of global sea-level rise was released in 2007. Based on that report and studies since then, Dalrymple sees two major effects.

“One is that as the sea level rises, it inundates² low-lying area," he says. "And then the second major issue is because the sea level is higher, when there are coastal³ storms, then they reach further inland. The damage due to coastal storms will increase."

As the climate warms, more extreme storm surges and high waves are expected, raising the risk of flooding, coastal erosion and wetland loss. Up and down the California coast, highways, sports stadiums and housing developments are only a meter or so above the highest tides. 

San Francisco International Airport would flood with 40 centimeters of sea level rise, a likely scenario⁴ within a few decades, according to the report. 

While the outlook for Washington and Oregon is a bit brighter, Dalrymple says a powerful earthquake could raise sea levels dramatically. 

“And that will cause the sea level rise in those two states, comparable to what 100 years of sea level rise would do, except it would be a very dramatic happening in minutes. So as the land drops a meter or two, that is like one or two meters of sea level rise.”

That would be in addition to the 60-centimeter rise already predicted over the next century, due to global warming, Dalrymple says.

Sea level rise also threatens the U.S. east coast. A United States Geological Survey (USGS) study looked at a 1,000-kilometer stretch of America’s Atlantic seaboard, from Massachusetts down to North Carolina.

The area had already been labeled a “hotspot” for sea level rise but the outlook could be even worse than the experts thought.

“Over a 60-year period, the rates within that hotspot area have increased between two and 3.7 millimeters per year," says USGS oceanographer and lead author, Asbury Sallenger. "An increase like that is three to four times greater than you find in the average increase in rate of sea level rise over the same period.”

The report finds the sea-level rise on the East Coast is consistent with a slowdown in the circulation of the Atlantic Ocean. Computer models show a change in circulation may be tied to changes in water temperature, salinity⁵ and density⁶ in the sub-polar north Atlantic.

“A slowdown of the circulation actually can lead to changes in currents that run along the eastern seaboard in a way that translates to increasing sea level in the northeast United States,” Sallenger says.

He hopes data from the two coastal studies will be useful tools that help public officials and ordinary citizens better respond to the looming⁷ challenges posed by global climate change.

1 glaciers   

冰河，冰川( glacier的名词复数 )

参考例句：

• 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）

2 inundates   

v.淹没( inundate的第三人称单数 )；（洪水般地）涌来；充满；给予或交予（太多事物）使难以应付

参考例句：

• The river inundates the valley each spring. 那一条河流每年春天使山谷泛滥。 来自辞典例句
• A flood occurs when overflows or inundates land that's normally dry. 当水流过量或者淹没正常的土地时，洪水发生。 来自互联网

3 coastal   

adj.海岸的，沿海的，沿岸的

参考例句：

• The ocean waves are slowly eating away the coastal rocks.大海的波浪慢慢地侵蚀着岸边的岩石。
• This country will fortify the coastal areas.该国将加强沿海地区的防御。

4 scenario   

n.剧本，脚本；概要

参考例句：

• But the birth scenario is not completely accurate.然而分娩脚本并非完全准确的。
• This is a totally different scenario.这是完全不同的剧本。

5 salinity   

n.盐分；咸度；盐浓度；咸性

参考例句：

• In the sea water sampled the salinity is two parts per thousand.在取样的海水中，盐度为千分之二。
• In many sedimentary basins the salinity of the formation water increases with depth or compaction.在许多沉积盆地中，地层水的含盐量随深度或压实作用而增高。

6 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。

7 looming   

n.上现蜃景（光通过低层大气发生异常折射形成的一种海市蜃楼）v.隐约出现，阴森地逼近( loom的现在分词 )；隐约出现，阴森地逼近

参考例句：

• The foothills were looming ahead through the haze. 丘陵地带透过薄雾朦胧地出现在眼前。 来自《简明英汉词典》
• Then they looked up. Looming above them was Mount Proteome. 接着他们往上看，在其上隐约看到的是蛋白质组山。 来自英汉非文学 - 生命科学 - 回顾与展望