Complex sentence: When South America eventually separated from Antarctica, the development of the cold circum-Antarctic ocean current changed weather patterns across the world: for Australia-New Guinea, it brought a marked intensification of the drying trend.
Split into simpler sentences: When South America eventually seperated from Antarctica, the development of the cold circum-Antarctic ocean current changed weather patterns across the world. For Australia-New Guinea, it brought a marked intensification of the drying trend.