研究發(fā)現(xiàn)，地球的臭氧層仍然存在問題

研究發(fā)現(xiàn)，地球的臭氧層仍然存在問題

We've got good news and bad news. There's more evidence that the hole in the ozone layer over Antarctica is recovering and that humans' efforts are making a difference. At the same time, however, one study suggests the ozone layer is surprisingly thin at lower latitudes, where solar radiation is stronger and billions of humans live.

我們有好消息和壞消息。越來越多的證據(jù)表明，南極洲上空的臭氧層空洞正在恢復(fù)，人類的努力正在發(fā)揮作用。然而，與此同時(shí)，一項(xiàng)研究表明，低緯度地區(qū)的臭氧層出奇地薄，那里的太陽輻射更強(qiáng)，數(shù)十億人生活在那里。

This was Antarctica's ozone hole in September 2017. There was 20 percent less ozone depletion during the Antarctic winter than there was in 2005. (Photo: Kathryn Mersmann/NASA's Goddard Space Flight Center/YouTube)

Thanks to a satellite instrument built by NASA's Jet Propulsion Laboratory, scientists were able to accurately measure the levels of chlorine molecules, which deplete the ozone layer after they break off from human-made chlorofluorocarbons (CFCs). The result is a 20 percent reduction in ozone depletion compared to 2005, the first year that NASA made measurements of the ozone hole using the Aura satellite.

多虧了美國宇航局噴氣推進(jìn)實(shí)驗(yàn)室制造的一個(gè)衛(wèi)星儀器，科學(xué)家們能夠精確測量氯分子的含量。其結(jié)果是，與2005年相比，臭氧層損耗減少了20%。2005年是美國宇航局首次使用Aura衛(wèi)星測量臭氧層空洞。

Thinning ozone layer

臭氧層變薄

The ozone layer is located within Earth's stratosphere. (Photo: Kaiskynet Studio/Shutterstock)

They do have some suspicions, though, noting that climate change is altering the pattern of atmospheric circulation, which causes more ozone to be carried away from the tropics. Another possibility is that chemicals known as very short-lived substances (VSLSs) — which contain chlorine and bromine — could be destroying ozone in the lower stratosphere. VSLSs include chemicals used as solvents, paint strippers and degreasing agents, and even one used as an ozone-friendly alternative to CFCs.

不過，他們也有一些懷疑，他們注意到氣候變化正在改變大氣環(huán)流的模式，導(dǎo)致更多的臭氧從熱帶地區(qū)被帶走。另一種可能性是，被稱為非常短命物質(zhì)(VSLSs)的化學(xué)物質(zhì)——含有氯和溴——可能正在破壞平流層下部的臭氧。VSLSs包括用作溶劑的化學(xué)物質(zhì)、油漆剝離劑和脫脂劑，甚至還有一種作為氯氟烴的臭氧友好替代品。

Phasing out CFCs

逐步淘汰氟利昂

CFCs — which are comprised of chlorine, fluorine and carbon — were used to create all sorts of products, including aerosol sprays, packing materials and refrigerants. But once these molecules were exposed to the UV rays of the sun, the chlorine would break off and destroy ozone molecules, which is what created the ozone hole.

氯氟烴——由氯、氟和碳組成——被用來制造各種各樣的產(chǎn)品，包括氣溶膠噴霧劑、包裝材料和制冷劑。但是一旦這些分子暴露在太陽紫外線下，氯就會(huì)斷裂并破壞臭氧分子，這就是造成臭氧空洞的原因。

Recovering ozone hole

恢復(fù)臭氧層空洞

Launched in 2004, the Aura satellite studies Earth's ozone layer, air quality and climate. (Photo: NASA)

Strahan and Douglass used the Microwave Limb Sounder (MLS) aboard the Aura satellite to collect their measurements, a sensor that can measure trace atmospheric gases without the aid of sunlight, a useful feature for studying the ozone layer when there's limited sunlight available. Ozone levels over the Antarctic change starting at the end of the Antarctic winter, around early July to mid-September.

Strahan和Douglass使用Aura衛(wèi)星上的微波測邊儀(MLS)來收集他們的測量數(shù)據(jù)，這是一種可以在沒有陽光的情況下測量大氣中痕量氣體的傳感器，這在研究有限陽光下的臭氧層時(shí)是一個(gè)有用的特性。南極上空的臭氧水平在南極冬季結(jié)束時(shí)開始變化，大約在7月初到9月中旬。

Global problem, global response

全球問題，全球反應(yīng)

As for ozone depletion at lower latitudes, Ball and his colleagues note that it's not as extreme as what was happening above Antarctica a few decades ago, but the effects could still be more severe due to conditions closer to the equator.

至于低緯度地區(qū)的臭氧損耗，鮑爾和他的同事注意到，它不像幾十年前南極上空發(fā)生的情況那么極端，但由于更靠近赤道，其影響可能會(huì)更嚴(yán)重。

The Montreal Protocol is working for the ozone hole over Antarctica, the study's authors write, although its efficacy may start to be questioned if the thinning trend continues elsewhere. They argue these findings illustrate the value of how closely we've learned to study the ozone layer since the 1980s, as well as the need for ongoing research to reveal what exactly is going on at lower latitudes.

該研究的作者寫道，《蒙特利爾議定書》正在為南極洲上空的臭氧層空洞效力，盡管如果其他地方的臭氧層空洞繼續(xù)變薄，該議定書的效力可能會(huì)開始受到質(zhì)疑。他們認(rèn)為，這些發(fā)現(xiàn)說明了自上世紀(jì)80年代以來我們對臭氧層研究的深入程度，以及揭示低緯度地區(qū)究竟發(fā)生了什么的持續(xù)研究的必要性。

"The study is an example of the concerted international effort to monitor and understand what is happening with the ozone layer," Ball says. "Many people and organizations prepared the underlying data, without which the analysis would not have been possible."

鮑爾說:“這項(xiàng)研究是國際社會(huì)齊心協(xié)力監(jiān)測和了解臭氧層狀況的一個(gè)例子。”“許多人和組織準(zhǔn)備了基礎(chǔ)數(shù)據(jù)，沒有這些數(shù)據(jù)，分析就不可能進(jìn)行。”