Evolution of surface UV radiation in rela- tion to ozone depletion and climate change
Résumé
exposure to ultraviolet (UV) radiation is known to be a risk factor for several diseases such as skin cancers and cataracts. On the other hand, a number of studies have described the benefits of UV exposure in relation to the synthesis of vitamin D and prevention of several diseases. the evolution of surface UV radiation has been under scrutiny in the last decades due to the discovery of ozone depletion in the middle atmosphere. atmospheric ozone is the main atmospheric absorber of UV-B radiation (280 – 320 nm spectral range) and its depletion has raised concerns about the protection of human populations, living organisms and ecosystems against dangerous UV radiation. the rapid understanding in the 1980s of the main processes involved in stratospheric ozone destruction, which incriminated halogen substances emitted by human activities, led to the regulation of the emission of these ozone-depleting substances (ODs). since then, ODs abundances have continued to increase up to the mid or end of the nineties, depending on latitude, and have now started to decrease slowly. as a consequence, the ozone layer has stabilized and shows signs of recovery. While the decrease of ODs content is expected to be the dominant cause of the future long-term evolution of stratospheric ozone, climate change effects and natural variability of the atmosphere still hinder the unambiguous detection of the recovery expected from ODs decrease.
Chemistry-Climate models indicate that minimum levels of stratospheric ozone have been reached in the early 21st century. the recovery of the ozone layer is forecasted in a period ranging between 2015 and 2030 in the northern hemisphere and between 2030 and 2040 in the southern hemisphere, with a disappearance of the antarctic ozone hole after 2050. Due to climate change induced effects on transport processes and temperature climatology in the middle atmosphere, models simulate a super-recovery of ozone in the polar and mid-latitude regions and an under recovery in the tropics. the future evolution of ozone will thus have an impact on surface UV at global scale and on the health related UV doses.
this presentation will review the latest results on the past and future long-term evolution of global ozone and surface UV. projected changes in clear-sky erythemal and vitamin D effective UV doses for europe over the period 2006 to 2100, based on CMip5 simulation of total ozone and aerosols will also be presented.