(ORDO NEWS) — Ozone may be dampening one of the Earth‘s most important cooling mechanisms, making it a more significant greenhouse gas than previously thought, the researchers found.
A new study has found that changes in ozone levels in the upper and lower atmospheres are responsible for almost a third of the warming observed in ocean waters bordering Antarctica in the second half of the 20th century.
Deep and rapid warming in the Southern Ocean affects its role as one of the main regions to absorb excess heat as the planet warms.
Much of this warming has been the result of an increase in ozone in the lower atmosphere. Ozone – one of the main components of smog – is already a dangerous pollutant, but a study shows it could also play a major role in climate change in the coming years.
Ozone near the Earth’s surface is harmful to humans and the environment, but this study shows that it also has a big impact on the ocean’s ability to absorb excess heat from the atmosphere.
The new study, led by an international team of scientists led by the University of California, Riverside, is published in the journal Nature Climate Change.
The team, supported by the US National Science Foundation, used models to simulate upper and lower atmospheric ozone changes between 1955 and 2000 to isolate them from other influences and expand current understanding of their impact on heat absorption by the Southern Ocean.
“This study highlights the complexity of the atmosphere-ocean interactions that play a role in the Earth’s heat balance and the need for ongoing observations of the atmosphere-ocean system and robust models to model these processes,” said Sean Kennan, Program Director, NSF’s Division of Ocean Sciences.
Modeling showed that decreases in ozone in the upper atmosphere and increases in the lower atmosphere contributed to the warming observed in upper ocean waters at high latitudes.
The study found that the increase in ozone in the lower atmosphere caused 60% of the total ozone-induced warming that was observed in the Southern Ocean during the study period – much more than previously thought.
Ozone is formed in the upper atmosphere as a result of the interaction of oxygen molecules and ultraviolet radiation from the sun. In the lower atmosphere, it is formed from chemical reactions between pollutants such as car exhaust and other emissions.
Changes in atmospheric ozone affect westerly winds in the Southern Hemisphere and cause contrasting levels of salt and temperature near the surface in the Southern Ocean. Both of these factors affect ocean currents in different ways, thereby influencing the absorption of heat by the ocean.
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