I also recommend Eco-Logical and Climate Concerns, since the climate is changing so drastically. As a fellow Pennsylvanian, I recommend the video "The Sky is Pink" in Eco-logical's discussion Fracking Releases Methane.
After you've searched for topics of interest in "Groups" above and in the "Forums", don't forget to look at recent activity which hides along the right margin of the page all the way at the bottom.
Hello Greg Welcome to this world of rationality, truth and peace, where common sense and science lead to freethinking wisdom --- as you know as a true atheist. We invite you to join the busy group "ORIGINS: Universe, Astronomy, Life, Earth, Humans, Religion, Gods, Atheism, Evolution, Darwin..." with 730 discussion topics and 3600 members. http://www.atheistnexus.org/group/originsuniverselifehumankindanddarwin Terry