Last week the hole in the ozone layer over Antarctica reached a moderately large size for the third year in a row – larger than the entirety of North America – but experts say it is still expanding overall, despite recent high altitudes due to colder weather. shrinking from.
According to NASA, the hole in the ozone layer reached its largest size of more than 10 square miles (26.4 million square kilometers) on October 5, the largest since 2015. The scientists noted that since the south polar regions at altitudes of 12 to 20 kilometers (7 to 12 mi) where the hole is located have had cooler-than-normal temperatures, conditions are ripe for chlorinated chemicals to react with ozone molecules. Huh. and destroy them.
“The general trend is for improvement. This year it has gotten a little worse as it has cooled down a bit,” said Paul Newman, chief terrestrial scientist at NASA’s Goddard Space Flight Center, which monitors ozone depletion. “All the data indicates that ozone is recovering.”
Seeing the maximum size of the hole in the ozone layer, especially in October, can be misleading, said Susan Solomon, an MIT ozone gas scientist.
“Ozone depletion begins later and takes longer for the hole to reach its maximum size, and the holes are generally shallower,” Solomon said in an email Thursday, which is a critical month for ozone recovery. Yes, not October.
Highly chlorinated and bromide chemicals in the atmosphere deplete the Earth’s protective ozone layer. Newman explained that the low temperatures create clouds that release these chemicals. The colder, the more clouds and therefore the bigger the hole in the ozone layer.
Climate change science says Earth’s surface is warmed by carbon trapped in heat from burning coal, oil and natural gas, but the upper stratosphere, on top of the trapped heat, Newman said. However, the hole in the ozone layer is slightly below the region that is known to be cooler due to climate change, he said. Other scientists and investigations link the region’s cooling to global warming.
“The fact that the stratosphere is showing signs of cooling due to climate change is worrying,” said Martin Chipperfield, an atmospheric scientist at the University of Leeds. What is worrying is that climate change and efforts to reduce the ozone hole are intertwined.