The mighty polar bear has long been the poster child for the effects of global warming in the Arctic, but the microscopic diatom tells an equally powerful story. Diatoms are a type of algae that form the base of the food chain in watery habitats the world over. Disturbances among lake diatoms have exposed the impacts of rapid warming in the Hudson Bay Lowlands of eastern Canada, researchers reported Oct. 9 in the Proceedings of the Royal Society B.