Fort McMurray Today: Environmental groups have stepped up their attacks on the Alberta oilsands, launching an ad campaign against the “dirtiest oil on earth” ahead of U.S. President Barack Obama’s visit next week. Obama has reportedly planned a quick visit — about six hours — to Canada on Feb. 19. The network of Canadian and American environmental groups is launching a cross-border campaign urging the U.S. president to stand strong on his new energy economy agenda and reject entreaties from …