Posted on the website on 6 March 2001.
The History of the UV Radiation Climate of the Earth—Theoretical and Space-based Observations¶
Article first published online: 1 MAY 2007
Photochemistry and Photobiology
Volume 73, Issue 4, pages 447–451, April 2001
How to Cite
Cockell, C. S. and Horneck, G. (2001), The History of the UV Radiation Climate of the Earth—Theoretical and Space-based Observations. Photochemistry and Photobiology, 73: 447–451. doi: 10.1562/0031-8655(2001)0730447THOTUR2.0.CO2
- Issue published online: 1 MAY 2007
- Article first published online: 1 MAY 2007
- Received 11 January 2001; accepted 21 February 2001
In the Archean era (3.8–2.5 Ga ago) the Earth probably lacked a protective ozone column. Using data obtained in the Earth's orbit on the inactivation of Bacillus subtilis spores we quantitatively estimate the potential biological effects of such an environment. We combine this practical data with theoretical calculations to propose a history of the potential UV stress on the surface of the Earth over time. The data suggest that an effective ozone column was established at a pO2 of ∼5 × 10−3 present atmospheric level. The improvement in the UV environment on the early Proterozoic Earth might have been a much more rapid event than has previously been supposed, with DNA damage rates dropping by two orders of magnitude in the space of just a few tens of millions of years. We postulate that a coupling between reduced UV stress and increased pO2 production could have contributed toward a positive feedback in the production of ozone in the early Proterozoic atmosphere. This would contribute to the apparent rapidity of the oxidation event. The data provide an evolutionary perspective on present-day Antarctic ozone depletion.