Beluga whales in the Disney+ docuseries 'Secrets of the Whales' (Peter Kragh/National Geographic for Disney+).
CNN  — 

There’s no one way for documentary fare to acknowledge Earth Day, but the programs generally fall into one or more of four distinct buckets in regard to the health of the planet: Depressing, vaguely hopeful, star-studded, and celebrating the natural world to highlight what we might be losing.

As shades of green go, “depressing” seems a little less prevalent this year, though it’s always an undercurrent of this annual programming wave, which seeks to vividly present nature and find rays of hope amid the gloom, while warning what will happen if the climate crisis goes unaddressed.

The latest crush of TV and movies devoted to Earth Day, which is officially marked on April 22, can be seen in the spectrum of projects scheduled, including a pair featuring 94-year-old naturalist David Attenborough, and two more involving 18-year-old activist Greta Thunberg, already profiled last year in the documentary “I Am Greta.”

Although most of the programs arrive on Earth Day, a few are getting an early jump, and one of the more interesting has already landed on Apple TV+: “The Year Earth Changed,” a BBC documentary – fronted by Attenborough – that charts the dramatic changes experienced across the globe as human activity slowed during the pandemic and animal life thrived.

Attenborough’s narration calls the effects “a global experiment of epic proportions,” one that saw “remarkable things start to change in the natural world: Clearer air. Cleaner waters. And animals starting to flourish in ways we hadn’t seen for decades.” The question, as he notes, is whether any of those lessons and gains can be advanced once humankind, and its harmful influence on the climate, rebounds to pre-pandemic levels.

Attenborough also narrates Netflix’s three-part “Life in Color With David Attenborough,” a more celebratory look at the role vibrant colors play in animal adaptations.

Sir David Attenborough in the Netflix docuseries 'Life in Color.'

Not to be outdone, Thunberg will be featured in “Greta Thunberg: A Year to Change the World,” a three-part documentary premiering April 22 on PBS; and “Action Planet,” a Discovery+ series about the environmental work of “high-profile changemakers,” among them Thunberg as well as Common, Jane Fonda, Matt Damon, Joseph Gordon-Levitt, and Adrian Grenier.

In a bit of Disney synergy, the ABC TV stations will team with National Geographic on “Our America: Climate of Hope,” a special featuring meteorologists focusing on the impacts of extreme weather and what can be done in the face of the climate crisis. CBS is tackling the issue across its news platforms under the heading “Eye on Earth: Our Planet in Peril.”

A by-no-means-comprehensive list of other Earth Day-related programming follows:

“The Secrets of the Whales” (April 22, Disney+): A four-part National Geographic documentary produced by director/conservationist James Cameron, the film offers a detailed exploration of how whales communicate and interact, featuring explorer/photographer Brian Skerry. It’s narrated by Cameron’s “Avatar” and “Aliens” star Sigourney Weaver.

'Cher & the Loneliest Elephant' premieres on Paramount+, and later Smithsonian Channel (Zoobs Ansari).

“Cher & the Loneliest Elephant” (April 22, Paramount+ in the US, Smithsonian Channel in the UK): Definitely one for the “star-studded” category, Cher becomes involved in an effort to save the “world’s loneliest elephant,” Kaavan, which involves moving the four-ton elephant more than 2,300 miles.

“2040” (April 22, CW): The CW will air documentary filmmaker Damon Gameau’s speculative examination of what life could look like 20 years from now, aimed at his young daughter.

“The Race to Save the World” (April 22, Virtual cinemas): Described as “a climate change film like no other,” director Joe Gantz’s documentary focuses on activists of various ages and backgrounds “in the trenches fighting for a livable future.”

“The Last Igloo”(April 19, BBC Select): Looking at igloos as a symbol of a way of life that’s being lost as snow and ice disappear.

“One Wild Day” (April 17, BBC America): A new BBC nature series follows different animals across a single day across the Earth.

“Through Greenland - With Nikolaj Coster-Waldau” (Topic): A five-part documentary featuring the “Game of Thrones” star, traveling his adopted country to reveal the effects of climate change.