by Deborah Zabarenko
A member of a team of Cambridge scientists trying to find out why Arctic sea ice is melting so fast, walks on some drift ice 500 miles (800 km) from the North Pole September 3, 2011.Photo: Stuart McDILL
Arctic sea ice, a key indicator of climate change, melted to its lowest level on record this year before beginning its autumnal freeze, researchers at the U.S. National Snow and Ice Data Center said on Wednesday.