Alarming observations have been reported on recent climate changes in the Arctic. Sea ice is thinning and shrinking, and its area was the lowest since 1979 when systematic microwave satellite observations began. Will the summertime ice completely disappear due to man-made greenhouse gases as predicted by climate models? Twenty-three experts from the United States and abroad gathered in January to address this question. The meeting was organized by George Kukla of Lamont-Doherty Earth Observatory and Roger Barry of the World Data Center for Glaciology in Boulder, Colorado. Additional scientists participated in the discussion sessions or contributed by mail.