NASA Reports Earth's Ozone Layer Holes Starting To Endow, How Hazard?
JAKARTA - Earth's ozone layer hole reportedly grew last week, even larger in size than North America. However, scientists say this size is still in a reasonable category.
"The overall trend is an upgrade. It's a little worse this year because it's a little colder this year. All the data says that ozone is improving," said NASA Space Aviation Center Chief Scientist Goddard Paul Newman, who tracks ozone depletion.
According to NASA's observation, the ozone hole peaked at a peak of more than 26.4 million square kilometers on October 5, the largest since 2015.
Scientists say because the temperature is cooler than usual in the south polar region at an altitude of 12 to 20 kilometers, where the ozone hole is located, the condition is ripe for chlorine chemicals that chew ozone.
Quoted from VOA, Sunday, October 16, top scientist from MIT, Susan Solomon stated that only looking at the maximum size of the ozone hole, especially this October, could be misleading.
"The ozone depletion will begin later and take longer to reach the maximum hole and the holes are usually shallower in September, which is the key month to look at ozone recovery, not October," Solomon said.
ozone depletion above the southern polar region is caused by high chlorine compounds in the stratosphere, most of which can be attributed to the use of chlorofluorocarbons (CFCs).
During Antarctica's winter, temperatures become low enough for polar stratosphere clouds (PSCs) to form at heights. These PSCs then provide surfaces for chemical reactions that convert CFCs into more active forms such as chlorine gases.
When sunlight returns at the start of the spring polar, ultraviolet radiation breaks down chlorine gas molecules and releases chlorine atoms, which then interact with and destroy ozone molecules.
As a result, Antarctic ozone holes always grow during spring, eventually stable when temperatures become too high for PSC.
The colder spring, the greater the potential for damage that explains why the ozone hole looks so large in recent years.
Measurements of ozone holes by NASA themselves show to have shrunk back to 22.67 million square kilometers (8.75 million square miles) on October 11.
The minimum thickness of ozone above the south polar region was recorded at 97 units of Dobson on October 1, but rose to 105 units of Dobson ten days later.
Most likely, cold temperatures are also responsible for the relatively large ozone holes this year, some suspect the illegal use of the CFC by factories in China may be one of the causes.
Lastly, Brian Toon of the University of Colorado said that major forest fires in Australia and recent underwater volcanic eruptions in Tonga were also claimed to have an impact.