Ban flew to Antarctica from southern Chile Saturday in preparation for a climate conference in Indonesia next month aimed at replacing the Kyoto accord, the BBC reported.
The U.N. chief wanted to see for himself the effects of climate change on the world's largest wilderness.
Scientists say some parts of Antarctica are melting fast and warn that over the next century melting of the polar ice caps could spark major flooding of lowlands and cause changes in world crop production.
Ban told reporters what he had seen flying over the melting glaciers was both "extraordinarily beautiful" and "disturbing."
He visited a research station set up by his home country of South Korea and was briefed by experts about the impact of global warming on the frozen continent.
"This is an emergency and for emergency situations we need emergency action," the U.N. chief said.