Summit Voice: Careful analysis of the marine fossil record from the Early Jurassic era (about 180 million years ago), suggests that warmer global temperatures and lower oxygen levels led to dramatic ecosystem changes, with a near extinction of ocean life. Those ecosystems later rebouned, but with a completely different species composition, according to Plymouth University (UK) scientists who studied ocean sediments along the North Yorkshire coast. "Our study of fossil marine ecosystems shows that if global warming...