CNN Worldwide will make Planet in Peril, its four-hour documentary investigation into threats to the world's environment, available in its entirety through services including the iTunes Store, Netflix and Amazon.com.

"Planet in Peril is essential viewing for anyone who cares about the environment," said Jon Klein, president of CNN US. "To treat Planet in Peril as the ground-breaking documentary that it is, we felt compelled to make this investigation as available as possible in as many formats as possible."

The documentary, filmed in a high-definition format, will be available through iTunes US (initially) at a cost of $1.99 per episode.

CNN is also making the video available through Netflix, Amazon.com, Sprint mobile phones equipped with access to CNN Mobile Live and by vide-on-demand through cable TV firms.

CNN on Sunday, 21 October, offered exclusive, advance screenings of a 40- minute excerpt of the documentary at Apple Stores in New York City, Los Angeles, Chicago, San Francisco and London.

The broadcaster has also released a selection of special reports relating to the investigation across multiple CNN Worldwide networks and platforms. These include an exclusive REM song, a special investigative report, a daily podcast and a viewing guide for educators.