November 3, 2012 (San Diego) -- Dear EarthTalk: I heard that the Arctic summer sea ice is at its lowest level since we began recording it. What are the implications of all this melting?   -- Jo Shoemaker, Bowie, MD

It is true that on September 16, 2012 the world reached a new low: The National Snow and Ice Data Center (NSIDC) reported that the extent of sea ice across the Arctic was at its lowest since satellite record-keeping began in 1979. On that date the sea ice reached its summer minimum, 1.32 million square miles, half of what the average size of summer ice was between 1979 and 2000, and almost 20 percent lower than the previous record minimum of 1.61 million square miles set on Sept. 18, 2007. NSIDC added that, despite especially warm conditions in 2007 being much more favorable for sea ice loss than this year, the thinning of sea ice due to climate change has made the ice more vulnerable to breakup and melting.