Throughout the history of life on Earth, UVB has been an environmental hazard for organisms, and ozone depletion occurring from the late 1970s to the late 1990s may have exacerbated already stressful conditions. The current stabilization and gradual reduction in the concentration of synthetic ozone-depleting substances should result in restoration of the ozone column to pre-1980 concentrations within the next 100 years. However, UVB-induced ecological changes that have occurred or will continue to occur in the coming decades are irreversible. Although some dire predictions were made in the past, there is no evidence of any ecosystem collapse, even in Antarctica where ozone depletion annually continues to exceed 50% and declines in primary productivity have been measured at up to 12%. Ecosystem modification has certainly taken place, but the long-term ramifications are not known.
There are indications that global warming could enhance ozone depletion even in the absence of anthropogenic pollutants, so the fate of the ozone layer is still uncertain. However, even without ozone depletion (i.e., with a normal ozone column), the amount of UVB passing through the atmosphere is sufficient to have measurable negative impacts on organisms and understanding the role of UVB in biosphere continues to be an important ecological issue.
See also: Global Warming Potential and the Net Carbon Balance; Oxygen Cycle.
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