Is the ozone hole a hoax? An international study led by IIT Kharagpur reveals shocking details | Science and Environment News

KOLKATA: A study led by a senior professor at IIT-Kharagpur in collaboration with international researchers has dismissed earlier claims of a “severe ozone hole” in the tropical stratosphere after analysing 42 years of data. The study, titled “No severe ozone depletion in the tropical stratosphere in recent decades”, claims that there has been no significant ozone depletion in the tropics nor is there any associated health threat, according to a statement from IIT Kharagpur.

Led by Jayanarayanan Kuttippurath of the Centre for Ocean, River, Atmospheric and Earth Sciences (CORAL) at IIT Kharagpur, his team analysed ozone measurements made by ground-based sondes (instruments to measure ozone levels) and satellites to examine the depletion of the ozone layer in the tropics over the past five decades (1980-2022). Their findings contradict previous research suggesting that a potential ozone hole could affect the health of about half of the world’s tropical population.

“Previous research suggested that such an ozone hole could potentially affect the health of about half of the world’s population living in tropical regions, but there was no observational evidence,” the statement said. The researchers found that the amount of column ozone in the tropics is relatively small compared to high and mid-latitudes.

There is no observational evidence to support a severe decline in stratospheric ozone in the tropics. The study indicates that current knowledge and data do not support the possibility of an ozone hole forming outside Antarctica. Stratospheric ozone is an important component of the atmosphere. Significant changes in its concentrations have major consequences for the environment, ecosystems and public health.

The study used extensive ground-based, satellite and reanalysis data, and showed no strong evidence of a significant ozone hole in the tropics. Average ozone levels in these regions remain well above the critical threshold used to define an ozone hole, the statement said. “The amount of column ozone in the tropics is relatively small compared to high and mid-latitudes. In addition, the trend in tropical total ozone is very small as estimated for the period 1998-2022. No observational evidence was found to indicate severe stratospheric ozone depletion in the tropics,” the statement added.

“Furthermore, current knowledge and observational evidence do not at all support the possibility of an ozone hole occurring outside Antarctica at present,” it said. According to the statement, previous studies reporting the existence of an ozone hole were based on inadequate data, mainly from the surface up to an altitude of 11 km, which is insufficient to accurately assess ozone levels at the critical altitude of 15 to 20 km.

The IIT-led research attributed any observed decline in tropical ozone levels to atmospheric dynamics rather than chemical depletion. “In contrast to an earlier claim, our study concludes that there is no ozone hole in the tropics and hence there is no health threat associated with it. Moreover, an ozone hole in the tropics is highly unlikely with respect to current halogen levels. Average ozone values ​​are always around 260 DU in the tropics, which is well above the ozone hole criterion of 220 DU,” Kuttippurath said.

He also noted that any slight decreases observed in tropical ozone levels in recent decades are due to changes in atmospheric dynamics rather than chemical processes. Ozone holes, as is known, are confined to Antarctica due to unique conditions such as extremely cold temperatures, he said.