Watch Carl Sagan warn that greenhouse gases cause global warming (in 1990!)

Published 10/03 2013 11:47AM

Updated 02/18 2014 06:08AM

Carl Sagan was the featured speaker at the Interparliamentary Conference on the Global Environment in 1990. More than 40 countries met to discuss strategies on key issues on the environment. (Posted by the Film Archives)

Copyright 2015 Nexstar Broadcasting, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.