Development of a methodology to quantify UV-B flux through time using UV-B absorbing compounds contained in fossil Pinus spp. sporopollenin
UV-B radiation currently represents approximately 1.5% of incoming solar radiation. However, significant changes are known to have occurred in the amount of incoming radiation both on recent and geological timescales due to stratospheric ozone loss, solar activity1, Milankovitch oscillations, volcanic events and variations in cloud cover. Estimates from modelling suggest that in some intervals of time (e.g. End Permian), incoming UV-B could have been up to 80% higher than present2. If these estimates are correct then the impact on terrestrial ecosystems could have been profound3.
Up until now it has not been possible to reconstruct a detailed measure of UV-B radiation through time. Instrumental records of UV-B radiation only extend back to the 1920s and modelling of past UV-B radiation is extremely difficult due to the unknown spatial variation in cloud and ash cover over time. Some success has recently been obtained in determining short-term variations. However, it has not been possible to obtain a systematic continuous record through time from one fossil species.
We have been undertaking research to determine the suitability of fossil Pinus spp. pollen to record variations in UV-B flux through the Cenozoic. Due to the large size of the grain (and therefore extraction from sedimentary sequences without the use of chemicals), and its long fossil history, we hypothesised that this grain could provide a good proxy for recording past variations in UV-B flux. Preliminary results indicate the excellent potential of this species for providing a quantitative record of UV-B variation during the Quaternary.
1. Rozema et al. (2002) Science, 296,1621–1622.
2. Beerling et al. (2007) Phil. Trans. Roy. Soc, A, 365, 1843-1866
3. Willis et al. (2009) Journal of Biogeograhpy, 36, 1630-1640
Further information for Dr. Angelica Feurdean can be found on her departmental site
Further information for Prof. Jelte Rozema can be found on his departmental site
Further information for Rob Broekman can be found on his departmental site