The phrase "summer sea" refers to the ocean or sea during the season of summer. It represents the calm, warm, and enjoyable nature of the sea during this time of year. Full definition
Now, models predict a complete loss of summer sea ice in 30 years. (livescience.com)
Three (3) respondents suggest a return toward the long term trend line of summer sea ice loss. (searcharcticscience.org)
It's important to note that the trend in summer sea ice extent is still downward, even if 2009 had more ice than 2007 and 2008. (searcharcticscience.org)