VOA标准英语2014--Study: Warmer World Will Produce Fewer Clou 气候变暖导致云层变少

 Study: Warmer World Will Produce Fewer Clou 气候变暖导致云层变少

With rising global carbon emissions¹, the planet will heat up and cloud cover will dissipate, according to a new study.

The concentration of heat-trapping carbon dioxide in the atmosphere has climbed 40 percent over the last century. And, the new study reports, in response to the release of CO2 emissions, from the burning of fossil fuels in power plants, cars and buildings, the Earth will continue to warm to dangerous levels. 

Steven Sherwood, a climate scientist at Australia's Centre of Excellence² for Climate System Science and lead author of the report, says the prediction of a 4-degree celsius³ warming is based on the role of water vapor⁴ in cloud formation.

“What we see in the observations is that when air picks up water vapor from the ocean surface and rises up, it often only rises a few kilometers before it begins its descent back to the surface," Sherwood said. "Otherwise it might go up 10 or 15 kilometers. And those shorter trajectories⁵ turn out to be crucial to giving us a higher climate sensitivity because of what they do to pull water vapor away from the surface and cause clouds to dissipate as the climate warms up.” 

Under this scenario⁶, in which clouds do not form, the Earth would absorb more sunlight. 

“The question for many years has been ,what is going to happen to the amount of low clouds?" Sherwood said. "Does it decrease when the Earth warms up or does it stay the same or maybe even increase?  And what we found is that it should be decreasing because of this mixing process, which pulls water vapor away from the layers where these clouds form and causes there to be fewer of them in the warmer atmosphere.” 

Climate models that show a slight global temperature response to carbon dioxide do not take the lower altitude water vapor process into account, according to Sherwood. Instead their simulations assume that all water vapor rises to 15 kilometers and forms clouds. 

“Estimates of the climate sensitivity that have been lower are founded on models of the atmosphere that are not consistent with observations,” he said.

When the processes in climate models are corrected to match the real world observations, the simulations produce cycles that take water vapor to a wider range of heights in the atmosphere. Sherwood says the study is yet another warning to curb⁷ emissions or deal with the impacts of climate change.

1 emissions   

排放物( emission的名词复数 )； 散发物（尤指气体）

参考例句：

• Most scientists accept that climate change is linked to carbon emissions. 大多数科学家都相信气候变化与排放的含碳气体有关。
• Dangerous emissions radiate from plutonium. 危险的辐射物从钚放散出来。

2 excellence   

n.优秀，杰出，(pl.)优点，美德

参考例句：

• His art has reached a high degree of excellence.他的艺术已达到炉火纯青的地步。
• My performance is far below excellence.我的表演离优秀还差得远呢。

3 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

4 vapor   

n.蒸汽，雾气

参考例句：

• The cold wind condenses vapor into rain.冷风使水蒸气凝结成雨。
• This new machine sometimes transpires a lot of hot vapor.这部机器有时排出大量的热气。

5 trajectories   

n.弹道( trajectory的名词复数 )；轨道；轨线；常角轨道

参考例句：

• To answer this question, we need to plot trajectories of principal stresses. 为了回答这个问题，我们尚须画出主应力迹线图。 来自辞典例句
• In the space program the theory is used to determine spaceship trajectories. 在空间计划中，这个理论用于确定飞船的轨道。 来自辞典例句

6 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。

7 curb   

n.场外证券市场，场外交易；vt.制止，抑制

参考例句：

• I could not curb my anger.我按捺不住我的愤怒。
• You must curb your daughter when you are in church.你在教堂时必须管住你的女儿。