Three stories, first appearing in this anthology, put together by Robert Silverberg. Code 15G. Tight, clean, flat, square, sharp and crisp book in paper jacket with small chips, nicks, tears and dust stains at the exposed portions of the flaps. The book went through at least two printings with the Book Club as well as the first hardcover release by Hawthorn, as small press in New York, which ceased publishing in early 80's. 

When this book was written, the ecological disaster that was being hyped in the mainstream press--and Science Fiction / Fact digests -- was "The Coming Ice Age". A few authors, Larry Niven among them, realized that the heat is the one universal product of all activities--be they geological, chemical, biological or industrial, and created one of the longest lasting Really Big Structures ever invented: the Ringworld in 1970. 

It remains to be seen which vision--the cold or the warm--is in our near future. This book explores the choice currently in vogue, featuring tales by Ursula K. LeGuin, Gene Wolfe and James Tiptree, Jr.