Stratospheric ozone is critical for shielding the biosphere against ultraviolet-B (UV-B) radiation and has been damaged in recent decades by the release of anthropogenic gases.
The ozone layer is expected to recover before the end of the 21st century, however a hole continues to appear over Antarctica each year. Ozone depletion usually peaks between
September and October, when fortunately, most Antarctic terrestrial vegetation and soil biota is frozen, dormant and protected under snow cover. Similarly, much marine life is
protected by sea ice cover. Since ozone depletion was most apparent in early Spring, most biota were unlikely to suffer severe UV-B exposure. However, in recent years, ozone depletion has persisted into the austral summer. Early summertime ozone depletion is concerning: high incident UV-B radiation coincident with snowmelt and emergence of vegetation will mean more exposure of biota. In addition, the start of summer is peak breeding season for many species, thus extreme UV-B exposure (UV index up to 14) may come at a vulnerable time in their life cycle. Climate change, including changing wind patterns and strength, and particularly declining sea ice, are likely to compound UV-B exposure of Antarctic organisms, through earlier ice and snowmelt. Antarctic field research conducted decades ago tended to study UV impacts in isolation and more research that considers combined climate impacts and the true magnitude and timing of current UV exposure is needed.