Nature: The cold water beneath the winter pack ice in Baffin Bay is getting warmer, according to measurements taken by thermometer-wearing narwhals1. The data collected from the diving mammals fill in a geographical and seasonal gap in the region’s climate records, as no winter temperatures were previously available from the area. The data also confirm that a warming trend measured during earlier summer-only studies of the West Greenland Current continued in the three years to 2007. “We basically knew…