Home / Science / News /  This gas may be weakening Earth's cooling mechanisms, warns Study. Details here

READING : This gas might emerge as a more significant greenhouse gas, after a study conducted warned that this highly reactive gas might be weakening one of Earth's important cooling system. 

The study published in the journal, 'Nature Climate Change', says that ozone in the lower atmosphere, in particular, contributed to warming in the southern ocean.

Ozone hit the headlines in the 1980s when a hole was discovered in the ozone layer high in the atmosphere over the South Pole, due to damage caused by chlorofluorocarbons (CFCs), a gas used in industry and consumer products.

What is Ozone

Ozone (O3) is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in the Earth's upper atmosphere. (the stratosphere) and lower atmosphere (the troposphere). Depending on where it is in the atmosphere, ozone affects life on Earth in either good or bad ways.

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 like vehicle exhaust fumes and other emissions.

Changes in ozone concentrations in the atmosphere affect westerly winds in the Southern Hemisphere as well as cause contrasting levels of salt and temperature close to the surface in the Southern Ocean. Both affect ocean currents in distinct ways, thereby affecting ocean heat uptake.

The ozone layer is vital as it filters dangerous ultraviolet radiation from reaching Earth's surface. This discovery led to the Montreal Protocol, an international agreement to halt the production of CFCs.

What does the study say about Ozone

-Ozone is more than just a pollutant, but may be playing a significant role in climate change.

-Ozone in the lower atmosphere, in particular, contributed to warming in the southern ocean.

-Changes to Ozone levels in the upper and lower atmosphere were responsible for almost a third of the warming seen 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 increase the currently poor understanding of their impact on the Southern Ocean heat uptake.

These simulations showed that a decrease in ozone in the upper atmosphere and increase in the lower atmosphere both contributed to the warming seen in the upper 2km of the ocean waters in the high latitudes by overall greenhouse gas increases.

Conclusions drawn from study

The study revealed that the increased ozone in the lower atmosphere caused 60% of the overall ozone-induced warming seen in the Southern Ocean over the period studied -far more than previously thought. This was surprising because tropospheric ozone increases are mainly thought of as a climate forcing in the Northern hemisphere since that is where the main pollution occurs.

Researchers speak

Dr Michaela Hegglin, an Associate Professor in atmospheric chemistry and one of the study's authors, said, "Ozone close to Earth's surface is harmful to people and the environment, but this study reveals it also has a big impact on the ocean's ability to absorb excess heat from the atmosphere."

"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," she added.

Dr Hegglin said, "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."

"There is hope to find solutions, and the success of the Montreal Protocol at cutting CFC use shows that international action is possible to prevent damage to the planet," she added.

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