READING : This gas could emerge as a more important greenhouse gas, after a study carried out warned that this highly reactive gas could weaken one of the Earth’s important cooling systems.
The study published in the journal “Nature Climate Change”, indicates that ozone in the lower atmosphere, in particular, has contributed to the warming of the Southern Ocean.
Ozone made headlines in the 1980s when a hole was discovered in the ozone layer above the South Pole, due to damage caused by chlorofluorocarbons (CFCs), a gas used in the industry and consumer products.
What is ozone
Ozone (O3) is a highly reactive gas composed of three oxygen atoms. It is both a natural product and an artificial product present in the Earth’s upper atmosphere. (the stratosphere) and the lower atmosphere (the troposphere). Depending on where it is in the atmosphere, ozone affects life on Earth either positively or negatively.
Ozone is created in the upper atmosphere by the interaction between oxygen molecules and UV radiation from the sun. In the lower atmosphere, it forms due to chemical reactions between pollutants such as vehicle exhaust and other emissions.
Changes in atmospheric ozone concentrations affect westerly winds in the Southern Hemisphere and cause contrasting near-surface temperature and salt levels in the Southern Ocean. Both affect ocean currents in distinct ways, thus affecting ocean heat absorption.
The ozone layer is vital because it prevents dangerous ultraviolet rays from reaching the Earth’s surface. This discovery led to the Montreal Protocol, an international agreement to stop the production of CFCs.
What does the ozone study say
-Ozone is more than just a pollutant, but can play an important role in climate change.
-Ozone in the lower atmosphere, in particular, has contributed to the warming of the Southern Ocean.
-Changes in ozone levels in the upper and lower atmospheres were responsible for almost a third of the observed warming in ocean waters bordering Antarctica in the second half of the 20th century.
How was the study conducted
The team used models to simulate changes in ozone levels in the upper and lower atmosphere between 1955 and 2000, to isolate them from other influences and augment the current poor understanding of their impact on heat uptake. of the Southern Ocean.
These simulations showed that a decrease in ozone in the upper atmosphere and an increase in the lower atmosphere both contribute to the observed warming in the upper 2 km of ocean waters at high latitudes through the overall increase in greenhouse gases. tight.
Conclusions drawn from the study
The study found that increased ozone in the lower atmosphere caused 60% of the ozone-induced global warming observed in the Southern Ocean during the study period – far more than previously thought. previously. This was surprising as increases in tropospheric ozone are primarily considered a climate forcing in the Northern Hemisphere, as this is where the main pollution occurs.
Dr Michaela Hegglin, Associate Professor of Atmospheric Chemistry and one of the study’s authors, said: “Ozone near the Earth’s surface is harmful to people and the environment, but this study finds that ‘It also has a big impact on the ocean’s ability to absorb excess. the heat of the atmosphere.”
“These findings are eye-opening and underscore the importance of regulating air pollution to prevent rising ozone levels and rising global temperatures,” she added.
Dr Hegglin said: “We have known for some time that the depletion of the ozone layer in the atmosphere has affected the surface climate in the Southern Hemisphere. Our research has shown that ozone is increasing in the lower atmosphere due to air pollution, which occurs mainly in the northern hemisphere and “leakage” in the southern hemisphere, is also a serious problem”.
“There is hope for solutions, and the success of the Montreal Protocol in reducing the use of CFCs shows that international action is possible to prevent damage to the planet,” she added. .
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