ScienceDaily: New evidence for ice-free summers with intermittent winter sea ice in the Arctic Ocean during the Late Cretaceous — a period of greenhouse conditions – gives a glimpse of how the Arctic is likely to respond to future global warming. Records of past environmental change in the Arctic should help predict its future behaviour. The Late Cretaceous, the period between 100 and 65 million years ago leading up to the extinction of the dinosaurs, is crucial in this regard because levels of …