Abstract

Exposure of biota to UV radiation is now recognized as largely detrimental even at levels typical of the natural atmosphere. The main factors controlling atmospheric UV radiation (solar zenith angle, ozone column amount, clouds and aerosols, surface reflections) are fairly well understood in prin... Show moreExposure of biota to UV radiation is now recognized as largely detrimental even at levels typical of the natural atmosphere. The main factors controlling atmospheric UV radiation (solar zenith angle, ozone column amount, clouds and aerosols, surface reflections) are fairly well understood in principle, but usually at least some of these are not known for an arbitrary location and time of interest. Reductions in stratospheric ozone have so far caused increases in biologically effective UV radiation of some 5–15% at middle latitudes, with larger percent increases in polar regions, but no significant increases in the tropics. Such increases, while difficult to detect directly, are estimated to have substantial public health impacts, e.g., on skin cancer incidence. International agreements to phase out the production and release of ozone-destroying chemicals are intended to prevent further depletion of stratospheric ozone, and lead to full recovery by the middle of the next century. The success of such agreements is contingent on strict global compliance, and assumes that our current understanding of ozone chemistry, which in many details is still evolving, is at least sufficient today to allow prediction of future atmospheric responses to anthropogenic emissions Show less