The latest research from the Arctic isn't good: Thick old ice is increasingly being replaced with thinner young ice, which melts quicker, meaning the ice is disappearing, according to a new report by NASA and the National Snow and Ice Data Center in Boulder (via National Geographic). As The Wall Street Journal notes, Arctic sea ice acts like a "giant mirror" that cools the planet by reflecting solar radiation back to space. With less ice, dark waters absorb more of the sun's heat, causing temperatures to rise and the climate to warm. University of Colorado at Boulder scientists say thicker ice that is two or more years old now constitutes less than 10 percent of the Arctic's wintertime ice cover--about one-third the annual average levels from 1981-2000. ScienceDaily sums it up in a headline, "Arctic Literally On Thin Ice, According To New Satellite Data," a story rife with footnotes.