 Volcanic activity has been observed in this area since the mid-1980s, with fresh lava flows on the southwest flanks of Heard Island.Satellite imagery shows that McDonald Island increased in size from about 1 to 2.5 square kilometers between 1994 and 2004, as a result of volcanic activity.In addition to new land being produced by volcanism, global warming of the climate is causing the retreat of glaciers on the islands ("see section below ").