Multistressors Related to Climate Change and Their Effects on Global Biodiversity during the Cenozoic Age

Sammanfattning: As multistressors have been shown to have significant effects on biodiversity and ecosystem functioning, the following study was made with the purpose of examining how a number of stressors specifically connected to climate change may have varied during the latest 65,5 million years and whether it is possible to predict potential effects on global biodiversity in the future. The analyses focused on global species richness during the Cenozoic age along with variables such as variations in atmospheric CO2, sea surface temperatures and global sea levels derived from analyses of various stable isotopes found in marine sediments. The results were primarily based on a Pearson Correlation Test and a One-Sample T-test, including data from Fossilworks.org and from an empirical literature study. Two of the variables, sea surface temperature and global sea level, had a significant relationship to global species richness. Variations in atmospheric CO2 were non-significant to species richness. The results suggest that multistressors related to various tectonic events, here expressed as changes in the oceanic circulation and the global mean temperature as a result of tectonic movements of the continents over time, had a higher impact on global biodiversity compared to stressors induced by changes in concentrations of CO2 in the atmosphere during the Cenozoic age, based on the time-scale used in this study. However, given the fact that the time-scale used here was measured in millions of years rather than hundreds of thousands of years, those results might be slightly difficult to compare directly to similar effects in the present and thus predict potential future effects on global biodiversity. Based on those results, it is suggested that changes in concentrations of atmospheric CO2 over time result in stress-related short-term effects on global biodiversity compared to other stressors induced by tectonic activity, although the former may still have some potential to affect global biodiversity in critical situations.