Warming worries for species numbers

Unsurprisingly, humans are increasingly concerned about their possible impact on climate change and its wider effects on the environment. But climate is well known to have varied in the past, so what has been the impact of these variations on the species of the time? Most attempts to look at this issue have focused on relatively short geological periods, limited geographical ranges or few taxonomic groups. But in a new study researchers at the University of York and the University of Leeds have examined the relationship between climate and biodiversity over the past 520 million years — almost the entire fossil record — and uncover an association between the two for the first time. They find that the record suggests rising global temperatures caused by climate change could trigger a huge extinction of plants and animals. The researchers looked at the fossil record against estimates of the low-latitude sea-surface temperature over geological time. When the Earth's temperatures were in the 'greenhouse' climate phase, they found that extinctions were relatively high. Conversely, during cooler 'icehouse' conditions, biodiversity increased. The results, reported in the Proceedings of the Royal Society series B (published online), suggest that the predictions of a rapid rise in the Earth's temperature due to man-made climate change could have a similar effect on current biodiversity. Peter Mayhew, one of the authors, said; " Our results provide the first clear evidence that global climate change may explain substantial variation in the fossil record in a simple and consistent manner. If our results hold for current warming-the magnitude of which is comparable with long-term fluctuations in the Earth's climate, they suggest that extinctions will increase. " The team found that of the mass extinction events in the earth's history, four were linked to greenhouse climates when the Feature Past periods of climate warming appear to be linked with lower biodiversity, raising further worries about the current climate. Earth's atmosphere was rich in carbon dioxide and methane. The largest ever extinction appears to have occurred 251 million years ago when fossil remains suggest 95 per cent of animal and plant species were killed off. The most likely cause of this extinction was floods of lava from the central Atlantic region, an event which created the ocean. " The risk of future extinction through rapid global warming is primarily expected to occur through mismatches between the climates to which organisms are adapted in …