Ozone layer - climate change interactions. Influence on UV levels and UV related effects

Abstract

Ozone in the atmosphere serves as a partially protective filter against the most harmful part of the solar UV-spectrum. Decreases in ozone lead to increases in ambient UV with a wide variety of adverse effects on human health, aquatic and terrestrial ecosystems and food chains. Human health effects include the incidence of skin cancer, cataracts and an impairment of the immune system. Ozone depletion has been observed over the past decades, and is most likely caused by man made emissions of halocarbons. The ozone depletion observed over the past decades has probably led to a 5-10% increase in harmful UV-radiation in large parts of Europe. Due to the long atmospheric life time of the ozone depleting substances the countermeasures agreed upon could at best be expected to lead to a slow recovery of the ozone layer in the next 50-60 years. However, in that best scenario it is assumed that no interaction occurs with climatological changes, and that a full global compliance with the strictest Amendments of the Montreal Protocol is obtained. Recent scientific evidence indicates that climate change might delay the recovery of the ozone layer by 10 to 20 years. This report summarizes the present knowledge on the climate-ozone interaction, the past and present UV-climate in Europe and dose-effect relationships for health and aquatic effects. Using this information a preliminary integrated risk analysis is provided for skin cancer risks and effects on the primary production of phytoplankton. Skin cancer risks due to ozone depletion peaks in the period 2050-2070. The excess risks in North western Europe due to ozone depletion is estimated at 50-60 additional cases per million per year if no climate-ozone interaction is included, and nearly 100 additional cases per million per year if the interaction is included. It should be noted that large uncertainties still exist in view of the gaps in the present knowledge on various aspects of the cause-effect chain.<br>