Research has revealed that ozone reduces the capacity of one of the most important regions to absorb excess heat on Earth. Ozone is essentially a greenhouse gas, but it depends on where it is present in the earth’s atmosphere to know whether it is beneficial or harmful.
Ozone in the upper atmosphere, which is formed naturally, protects the earth’s surface from UV rays, whereas the lower one tends to be harmful to humans and plants due to chemical reactions in the presence of sunlight. It results from air pollution, such as vehicle exhaust, industrial disposal, and other emissions.
However, a new study reveals that ozone in both the lower (the troposphere) and upper atmosphere (the stratosphere) is responsible for nearly one third of the warming in ocean waters near Antarctica. How does this happen?
New findings related to ground-level ozone
While ozone depletion in the atmosphere has an impact on the climate on Earth, particularly in the Southern Hemisphere, it turns out that increases in the tropospheric ozone caused by air pollution are also an issue that requires the utmost attention. Tropospheric ozone increases contribute to the warming in the Southern Ocean, even degrading its role as one of the earth’s heat sinks.
The study, led by the University of California, Riverside, simulated changes in ozone levels in the upper and lower atmosphere that occurred from 1955 to 2000. The simulation was carried out to better understand the influence of ozone level alterations on heat absorption in the Southern Ocean.
The simulation found that decreases in upper-level ozone and increases in lower-level ozone caused the upper 2 km of ocean waters to warm, with the total of overall greenhouse gas concentrations increasing.
The research, which has been published in Nature Climate Change, also showed that the rise of ground-level ozone was responsible for 60 percent of the warming in the Southern Ocean throughout the study period. It is substantially higher than anticipated because increases in tropospheric ozone have long been considered climate drivers in the Northern Hemisphere, where pollution is most prevalent.
Increased ozone in the lower atmosphere needs concern
Dr. Michaela Hegglin, one of the study’s authors, said, “These findings are an eye-opener and hammer home the importance of regulating air pollution to prevent increased ozone levels and global temperatures rising further still.”
According to Hegglin, who is also an Associate Professor in atmospheric chemistry, ozone near the Earth’s surface is not only damaging to humans and the environment, but it also has a great impact on the ocean’s ability to absorb excess heat from the atmosphere.
“We have known for a while that ozone depletion high in the atmosphere has affected surface climate in the Southern Hemisphere. Our research has shown that ozone increases in the lower atmosphere due to air pollution, which occurs primarily in the Northern Hemisphere and ‘leaks’ into the Southern Hemisphere, is a serious problem as well,” Dr. Hegglin added.
Credits: NASA’s Goddard
However, citing Phys, she was convinced that there was hope for a solution to this problem, recalling the 1980s discovery of an ozone hole caused by chlorofluorocarbons (CFCs). It led to the Montreal Protocol, an international treaty to protect the ozone layer from depletion due to substances like CFCs, chemicals used in industry and consumer products.
At the absolute least, international action is conceivable to prevent the devastation of our planet caused by changes in ozone levels, both in the upper and lower atmosphere.
