VOA标准英语2012--Global Warming Could Delay Next Ice Age

Global Warming Could Delay Next Ice Age

The next ice age could be delayed by tens of thousands of years due to excessive amounts of heat-trapping carbon dioxide in the atmosphere, which disrupts Earth’s natural cycle of warming and cooling, according to a study in Nature Geoscience.
Jim Channell analyzed¹ ice core and marine² sediment³ data from one million years of geologic⁴ history.
Channell, a distinguished⁵ professor of geology at the University of Florida, says one period, around 780,000 years ago, is remarkably⁶ like our own.
“It looks very similar because the orbital characteristics of the Earth, which is known from astronomers⁷, is a dead ringer for the orbital states that we have today. And we can use that as an analog⁸ to say, 'When will our interglacial state, which we’re in right now, go into the next glacial period?'”
Those orbital features - how the Earth revolves⁹ around the sun, the shape of its orbit, the tilt¹⁰ and wobble of the Earth on its axis¹¹ - undergo long, cyclical changes. Those changes directly affect the amount of radiation we receive from the sun, which in turn affects the Earth’s climate.
Based on these natural cycles, our current warming period should end within 1,500 years. Channell says what’s different from 780,000 years ago is that CO2 levels in the atmosphere back then were 240 parts per million, compared with 390 parts per million today.
“And so we can be fairly sure that we have, whether we like it or not, delayed the possibility that we will revert¹² from our present interglacial into a glacial state.”
Channell says the findings underscore the dramatic effect of CO2 - released by the burning of fossil fuels in our cars, power plants and buildings - on the Earth’s natural climatic systems.
“In other words, the orbital characteristics of the Earth, which [determine] the amount of radiation [reaching the earth] from the sun ... [and] which over millions of years have controlled the climate state on Earth, are no match for these excessive levels of CO2 in our atmosphere,” said Channell.
Cooling that would naturally occur in response to changes in the Earth’s solar orbit simply cannot keep up.
While a delayed ice age may sound like good news, Channell says, it isn’t.
The high concentration of heat-trapping greenhouse gases in the atmosphere is beginning to destabilize ice sheets in Greenland and Antarctica.
“Once you slough¹³ off the continental¹⁴ ice into the ocean, of course the consequence is sea level rise," said Channell.
"And it’s not being, I think, over-dramatic to say that considering the proportion of the world’s population that lives close to sea level, the implications of this sort of accelerated sea level rise are enormous,” he said.
Channel says those ice sheets are expected to continue to melt until the next phase of cooling begins. And when that will be is now in serious doubt.

1 analyzed   

v.分析( analyze的过去式和过去分词 )；分解；解释；对…进行心理分析

参考例句：

• The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
• The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程，因为对他来说，爱是个不可分析的迷。 来自《简明英汉词典》

2 marine   

adj.海的；海生的；航海的；海事的；n.水兵

参考例句：

• 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。

3 sediment   

n.沉淀，沉渣，沉积(物)

参考例句：

• 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。

4 geologic   

adj.地质的

参考例句：

• The Red Sea is a geologic continuation of the valley.红海就是一个峡谷在地质上的继续发展。
• Delineation of channels is the first step of geologic evaluation.勾划河道的轮廓是地质解译的第一步。

5 distinguished   

adj.卓越的，杰出的，著名的

参考例句：

• Elephants are distinguished from other animals by their long noses.大象以其长长的鼻子显示出与其他动物的不同。
• A banquet was given in honor of the distinguished guests.宴会是为了向贵宾们致敬而举行的。

6 remarkably   

ad.不同寻常地，相当地

参考例句：

• I thought she was remarkably restrained in the circumstances. 我认为她在那种情况下非常克制。
• He made a remarkably swift recovery. 他康复得相当快。

7 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

8 analog   

n.类似物，模拟

参考例句：

• The analog signal contains high-frequency video information,which helps make up the picture.模拟信号包括有助于构成图像的高频视频信息。
• The analog computer measures continuously,without proceeding step by step.模拟计算机不是一步一步地进行，而是连续地进行量度。

9 revolves   

v.（使）旋转( revolve的第三人称单数 )；细想

参考例句：

• The earth revolves both round the sun and on its own axis. 地球既公转又自转。 来自《现代汉英综合大词典》
• Thus a wheel revolves on its axle. 于是，轮子在轴上旋转。 来自《简明英汉词典》

10 tilt   

v.(使)倾侧；(使)倾斜；n.倾侧；倾斜

参考例句：

• She wore her hat at a tilt over her left eye.她歪戴着帽子遮住左眼。
• The table is at a slight tilt.这张桌子没放平，有点儿歪.

11 axis   

n.轴，轴线，中心线；坐标轴，基准线

参考例句：

• The earth's axis is the line between the North and South Poles.地轴是南北极之间的线。
• The axis of a circle is its diameter.圆的轴线是其直径。

12 revert   

v.恢复，复归，回到

参考例句：

• Let us revert to the earlier part of the chapter.让我们回到本章的前面部分。
• Shall we revert to the matter we talked about yesterday?我们接着昨天谈过的问题谈，好吗？

13 slough   

v.蜕皮，脱落，抛弃

参考例句：

• He was not able to slough off the memories of the past.他无法忘记过去。
• A cicada throws its slough.蝉是要蜕皮的。

14 continental   

adj.大陆的，大陆性的，欧洲大陆的

参考例句：

• A continental climate is different from an insular one.大陆性气候不同于岛屿气候。
• The most ancient parts of the continental crust are 4000 million years old.大陆地壳最古老的部分有40亿年历史。