Scientists: Ozone-Eating Chemical Mysteriously Rising

 

Scientists have found that levels of a now-banned chemical are rising again in Earth’s atmosphere.

The chemical is called CFC-11. It is the second most common kind of CFC, short for chlorofluorocarbon.

Chlorofluorocarbons were once widely used in many products. They were in air conditioners, refrigerators and spray cans. CFCs were added to insulation¹ foam² and fire suppression products.

Scientists discovered over 40 years ago that these man-made chemicals can reach Earth’s upper atmosphere. In the 1980s, CFCs were blamed for making a hole in Earth’s ozone³ layer.

Ozone is a form of oxygen. It is found in the air we breathe and in Earth’s stratosphere. The ozone layer protects life on our planet by blocking harmful radiation from the Sun.

But closer to Earth’s surface, ozone is a common pollutant⁴. It can harm people, crops and other plants.

The first step in international efforts to protect the ozone layer was an agreement called the Montreal Protocol⁵. It was signed in 1987 in an effort to end or sharply reduce the use of over 100 known ozone-eating CFCs. The protocol called for a complete ban on CFC-11 by 2010.

But scientists say the banned substance did not disappear. Beginning in 2013, emissions⁷ of CFC-11 mysteriously started rising again.

Results of a new study on the rising emissions were published in the science journal Nature.

Scientist Stephen Montzka was one of the writers of the study. He is with the United States National Oceanic and Atmospheric⁸ Administration. The agency keeps detailed⁹ information about Earth’s climate.

“We’re raising a flag to the global community to say, ‘This is what’s going on,’” Montzka said. “And it is taking us away from timely recovery of the ozone layer.”

He added that further work is needed to find out exactly why CFC-11 emissions are rising, and to find ways to stop it.

Countries have reported close to zero production of the chemical since 2006. But the study found that about 13,000 metric tons have been released each year since 2013.

Small amounts are thought to come from foam or buildings, but scientists say they are seeing much higher levels than that. The chemical can also be a byproduct in other chemical manufacturing, but it is supposed to be captured and recycled.

Each year, natural processes remove about 2 percent of CFC-11 from the air. Scientists say the chemical can stay in the atmosphere for about 50 years.

Measurements taken from around the world suggest the CFC-11 emissions are coming from northeastern Asia, the study found.

“Either someone’s making the banned compound or it’s sloppy¹⁰ byproducts that haven’t been reported as required,” Montzka said. He added that if the source of the new emissions can be identified and controlled soon, damage to the ozone layer should be minor¹¹. But he said if not dealt with soon, there could be great delays in the ozone layer’s recovery.

Other experts go even further.

Ross Salawitch is an atmospheric scientist with the University of Maryland. He told the Associated Press he thinks the rising chemical levels are the result of “rogue¹² production.” He added that if such increases continue, recovery of the ozone layer will be threatened.

I’m Bryan Lynn.

Words in This Story

refrigerator – n. a device that keeps food and drinks cool

foam – n. a soft material used in many products

emission⁶ – n. something released into the air, such as a chemical or gas

recycle – v. to reuse

global – adj. of or related to the whole world

sloppy – adj. not careful or neat

source – n. where something comes from

rogue – adj. used to describe something or someone that is different from others, usually in a dangerous or harmful way

journal - n. a magazine that reports on things of special interest to a particular group of people

1 insulation   

n.隔离；绝缘；隔热

参考例句：

• Please examine the insulation of the electric wires in my house.请检查一下我屋子里电线的绝缘情况。
• It is always difficult to assure good insulation between the electric leads.要保证两个电触头之间有良好的绝缘总是很困难的。

2 foam   

v./n.泡沫，起泡沫

参考例句：

• The glass of beer was mostly foam.这杯啤酒大部分是泡沫。
• The surface of the water is full of foam.水面都是泡沫。

3 ozone   

n.臭氧，新鲜空气

参考例句：

• The ozone layer is a protective layer around the planet Earth.臭氧层是地球的保护层。
• The capacity of ozone can adjust according of requirement.臭氧的产量可根据需要或调节。

4 pollutant   

n.污染物质，散布污染物质者

参考例句：

• Coal itself is a heavy pollutant.煤本身就是一种严重的污染物。
• Carbon dioxide may not be a typical air pollutant.二氧化碳可能不是一种典型的污染物。

5 protocol   

n.议定书，草约，会谈记录，外交礼节

参考例句：

• We must observe the correct protocol.我们必须遵守应有的礼仪。
• The statesmen signed a protocol.那些政治家签了议定书。

6 emission   

n.发出物，散发物；发出，散发

参考例句：

• Rigorous measures will be taken to reduce the total pollutant emission.采取严格有力措施，降低污染物排放总量。
• Finally,the way to effectively control particulate emission is pointed out.最后，指出有效降低颗粒排放的方向。

7 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。

8 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

9 detailed   

adj.详细的，详尽的，极注意细节的，完全的

参考例句：

• He had made a detailed study of the terrain.他对地形作了缜密的研究。
• A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。

10 sloppy   

adj.邋遢的，不整洁的

参考例句：

• If you do such sloppy work again,I promise I'll fail you.要是下次作业你再马马虎虎，我话说在头里，可要给你打不及格了。
• Mother constantly picked at him for being sloppy.母亲不断地批评他懒散。

11 minor   

adj.较小(少)的，较次要的；n.辅修学科；vi.辅修

参考例句：

• The young actor was given a minor part in the new play.年轻的男演员在这出新戏里被分派担任一个小角色。
• I gave him a minor share of my wealth.我把小部分财产给了他。

12 rogue   

n.流氓；v.游手好闲

参考例句：

• The little rogue had his grandpa's glasses on.这淘气鬼带上了他祖父的眼镜。
• They defined him as a rogue.他们确定他为骗子。