Decades after most countries stopped spraying DDT, frozen stores of the insecticide are now trickling out of melting Antarctic glaciers. The change means Adélie penguins have recently been exposed to the chemical, according to a new study. The trace levels found will not harm the birds, but the presence of the chemical could be an indication that other frozen pollutants will be released because of climate change, says Heidi Geisz, a marine biologist at Virginia Institute of Marine Science in Gloucester in the US. She led a team that sampled DDT levels in the penguins. She worries that glaciers could...