The highest levels of ultraviolet radiation from the Earth’s Sun ever recorded on Earth were the result of a “perfect storm” of location and events. This is the conclusion of Nathalie A. Cabrol of the SETI Institute and NASA Ames Research Center and colleagues based on astrobiological observations. The research was published in the July 8, 2014, edition of the journal Frontiers in Environmental Science.
The record breaking ultraviolet index of 43 was recorded on Dec. 29, 2003, around the Licancabur volcano and Laguna Blanca using instruments developed for the European Light Dosimeter Network. The scientists were not looking for extraordinary ultraviolet light. The study was part of an investigation of Mars-like environments in preparation for the Curiosity mission. The region is known to have higher than normal ultraviolet radiation due to the altitude.
The conditions that led to the highest levels of ultraviolet radiation ever recorded anywhere on Earth included the height of the region (between 14.000 feet and 17,500 feet), the position of the Sun near a midday zenith, and low ozone levels in the high altitude locations. A large solar flare that occurred two weeks before the record braking event added to the amount of ultraviolet light this region was exposed to. Local storms and high aerosol content in the atmosphere added to the conditions that precipitated the event.
The researchers conclude that there is no evidence that this singular event was directly related to climate change. The scientists do note that ultraviolet indices of seven to eight require sunscreen for people. An ultraviolet index of 26 has been recorded in nearby locations in previous years. People cannot withstand an ultraviolet index between 30 and 40. High ultraviolet indices also harm plant and animal life. One of the more destructive effects of extremely high ultraviolet indices is the destruction of DNA producing cancer. The researchers note that high ultraviolet indices will become more common.