Otsonieristymän

Otsonieristymän, a Finnish term, translates to "ozone depletion" in English. It refers to the observed thinning of the ozone layer in the Earth's stratosphere, particularly pronounced over the Antarctic region. The ozone layer plays a crucial role in absorbing most of the Sun's harmful ultraviolet (UV) radiation, protecting life on Earth.

The primary cause of ozone depletion is the release of certain manufactured chemicals, most notably chlorofluorocarbons (CFCs) and halons. These substances, once widely used in refrigerants, aerosols, and fire extinguishers, are very stable in the lower atmosphere. However, when they rise to the stratosphere, they are broken down by UV radiation, releasing chlorine and bromine atoms. These atoms then act as catalysts, destroying ozone molecules in a chain reaction.

The consequences of ozone depletion include an increase in the amount of UV-B radiation reaching the Earth's surface. This elevated UV exposure can lead to a rise in skin cancer and cataracts in humans, as well as harm to plant life and marine ecosystems.

International efforts to address ozone depletion have been largely successful. The Montreal Protocol on Substances that Deplete the Ozone Layer, signed in 1987, phased out the production and consumption of most ozone-depleting substances. As a result, the ozone layer is slowly recovering, and scientists predict it will return to pre-1980 levels by the end of the 21st century.