研究发现，地球的臭氧层仍然存在问题

研究发现，地球的臭氧层仍然存在问题

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.

我们有好消息和坏消息。越来越多的证据表明，南极洲上空的臭氧层空洞正在恢复，人类的努力正在发挥作用。然而，与此同时，一项研究表明，低纬度地区的臭氧层出奇地薄，那里的太阳辐射更强，数十亿人生活在那里。

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.

多亏了美国宇航局喷气推进实验室制造的一个卫星仪器，科学家们能够精确测量氯分子的含量。其结果是，与2005年相比，臭氧层损耗减少了20%。2005年是美国宇航局首次使用Aura卫星测量臭氧层空洞。

Thinning ozone layer

臭氧层变薄

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.

不过，他们也有一些怀疑，他们注意到气候变化正在改变大气环流的模式，导致更多的臭氧从热带地区被带走。另一种可能性是，被称为非常短命物质(VSLSs)的化学物质——含有氯和溴——可能正在破坏平流层下部的臭氧。VSLSs包括用作溶剂的化学物质、油漆剥离剂和脱脂剂，甚至还有一种作为氯氟烃的臭氧友好替代品。

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.

氯氟烃——由氯、氟和碳组成——被用来制造各种各样的产品，包括气溶胶喷雾剂、包装材料和制冷剂。但是一旦这些分子暴露在太阳紫外线下，氯就会断裂并破坏臭氧分子，这就是造成臭氧空洞的原因。

Recovering ozone hole

恢复臭氧层空洞

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卫星上的微波测边仪(MLS)来收集他们的测量数据，这是一种可以在没有阳光的情况下测量大气中痕量气体的传感器，这在研究有限阳光下的臭氧层时是一个有用的特性。南极上空的臭氧水平在南极冬季结束时开始变化，大约在7月初到9月中旬。

Global problem, global response

全球问题，全球反应

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.

至于低纬度地区的臭氧损耗，鲍尔和他的同事注意到，它不像几十年前南极上空发生的情况那么极端，但由于更靠近赤道，其影响可能会更严重。

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.

该研究的作者写道，《蒙特利尔议定书》正在为南极洲上空的臭氧层空洞效力，尽管如果其他地方的臭氧层空洞继续变薄，该议定书的效力可能会开始受到质疑。他们认为，这些发现说明了自上世纪80年代以来我们对臭氧层研究的深入程度，以及揭示低纬度地区究竟发生了什么的持续研究的必要性。

"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."

鲍尔说:“这项研究是国际社会齐心协力监测和了解臭氧层状况的一个例子。”“许多人和组织准备了基础数据，没有这些数据，分析就不可能进行。”