New Eden

Long before the start of the story, ecological disaster drove humanity undersea, or underground, or into space, away from a ravaged Earth. After living for quite a while in a City in A Bottle, it's a safe bet that someone will eventually find the way out and discover that the Earth has cleaned itself up nicely and now looks like the pristine Ghibli Hills, or why not, the Yosemite National Park.

Often used to make the point that the Earth would be a so much better place if it weren't for all the people, or more succinctly, that Ludd Was Right. (This suggests that massive genocide is justifiable, which some might see as an Unfortunate Implications). If a group of survivors in space is smaller and not planning on a disaster, that's But What About the Astronauts.

Anime and Manga

 * In Last Exile,
 * In Eureka Seven,
 * Twisted in Tokyo Mew Mew. The ancestors of the Big Bad and his followers were originally from Earth, and fled into space after it seemed like they were about to die off. They ended up on a very harsh planet, and upon finally returning to Earth, it looks perfect in comparison. Then they notice that humans are taking this paradise for granted, littering and polluting. This starts their initial desire to Kill All Humans.
 * The core MacGuffin of Nausicaa of the Valley of The Wind, though it looks less like a national park and more like a surreal, magical realm.
 * And there's the caveat that
 * Implied in Pale Cocoon.
 * Averted in Tengen Toppa Gurren Lagann: Simon, Kamina and Yoko manage to escape to the surface... only to find a dangerous land of beastmen kicking puppies with their Ganmen. Of course, that inspires Kamina to conquer the Surface.
 * Probably has something to do with Lordgenome wiping all spiral life off the surface of the planet and repopulating it with less capable non-spiral lifeforms. Those weird animals couldn't have evolved on their own.
 * In fact, Beastmen CAN'T evolve since they lack DNA. Which is also literally why they can't use Spiral Power.
 * Except
 * This trope is played a little bit, as this is exactly the kind of world Kamina wanted to live in.
 * Megazone 23 Part 3 has one city in the whole world, unsurprisingly named Eden. Though after meeting  Eve and Adam in the first two parts, it's hardly surprising.

Comic Books

 * This is pretty much Ra's al-Ghul's ultimate goal in The DCU, though needless to say, he's yet to succeed.
 * When Durham Red emerged from stasis to start her own series in 2000 AD, Earth was considered lost by the humans and mutants of the future. How did they lose it? Turns out that it was teleported to the far reaches of the galaxy to act as a prison for the most powerful mutant ever. In the meantime, the world recovered and became a lush paradise. Predictably, it did not stay this way.

Film

 * Used at the end of The Film of the Book Logan's Run.
 * Fight Club: Tyler Durden claims to have this as his dream.
 * The end of
 * In the film adaptation of Hellboy, this is Grigori Rasputin's motivation for trying to release the Ogdru Jahad. He's deluded of course, seeing as an actual vision of their return reveals a fiery wasteland.

Literature

 * The Machine Stops is a science fiction novella by E. M. Forster (Howards End, A Passage to India) set in a dystopian future where humanity lives in cubicles, communicating only via technology and experiencing everything second-hand. Outside the planet is livable but the titular Machine has rendered humanity dependent on it. Written in 1909.
 * Earth Abides (1949) is possibly an Ur Example, although it is mixed in with a healthy amount of Fridge Horror as the single family that repopulates Northern California gradually loses the ability to count or write down anything since they are too busy learning how to live off the land with copper arrowheads made out of pennies.
 * The ultimate destination for the main characters of Jeanne DuPrau's The City of Ember.
 * Believably used in Ben Elton's book This Other Eden, in which humanity has designed self-contained hermetic domes so that they can survive an ecological disaster that everyone believes is coming any day now. At the end of the book, a false warning is issued, causing everybody to retreat into their domes. The sudden absence of humanity allows the Earth's ecosystem to recover from the damage caused by pollution.
 * In D.J. MacHale's The Pilgrims of Rayne, Third Earth is like this - all the cities are underground and nature began to recover. Of course, this was after humanity had pretty much strip-mined the planet.
 * In Andre Norton's short story and novella "Outside", humanity sealed itself into domed cities when the surface of Earth became too polluted to support life. An epidemic later wiped out the adults. At the beginning of the story, the Rhyming Man - who looks like an old man - has begun luring some of the smallest children away. The older brother of a missing girl learns that they have been taken outside, which has fully recovered in the absence of people.
 * In Surreal 3000/Quatre Montréalais dans l'an 3000 by Suzanne Martel, a society has existed for a long time under Montreal's Mount Royal. When a kid accidentally finds a way out, he discovers that there are people living outside, despite his society's belief that the outside is deadly (he wears a breathing mask when he gets out, so he would have remained clueless if not for that encounter).
 * In the Novels of the Change, the total collapse of all modern technology means that things like bison and prairies make a hefty comeback, and wolves come back to the U.S. in force (also, lions and tigers. Blame soft-hearted zookeepers).
 * In The Stand by Stephen King, the characters watch America being reclaimed by nature, which seems to bounce back nicely in the absence of humans, despite The Antichrist lurking about ready to bring about the Apocalypse. In particular, The Professor Glen Bateman spends a large portion of time talking about how everything has changed, possibly for the better without all those people. On the other hand, The Plague killed almost all the domestic animals, too, and left the rats and such.
 * In the Star Wars Expanded Universe,

Live Action TV

 * Subverted in the new Battlestar Galactica, in which.
 * Kobol arguably plays it straight. It is implied that the war that broke out on Kobol ~3,600 years ago, and may or may not have been nuclear as well. By the time the Colonials arrive, the planet is lush and teeming with life. However, traces of the catastrophe and ruins of major cities are still present. Oh. And it is also cursed.
 * Doctor Who serial "The Sontaran Experiment", only now Earth (or at least the greater London area) looks like the Devonshire moors.
 * The Stargate SG-1 episode "The Gamekeeper" begins with this revelation, and the rest of the episode is dedicated (among other things) to SG-1's attempts to convince the locals stuck in a virtual reality that the planet did indeed repair itself, even though said locals believe otherwise.
 * And Dwight Schultz is hellbent on convincing them otherwise.

Tabletop Games

 * The shadow elves of Mystara, a D&D game setting, retreated underground to escape the Great Rain of Fire. Hundreds of years later, when the planet had recovered, their scouts rediscovered a path to the surface ... and ran smack into a subversion: rather than a paradise, the tunnel led to the Broken Lands, one of the few places on the planet that still looked like a radioactive wasteland. They went back underground and stayed put for another thousand years.

Video Games

 * Breath of Fire: Dragon Quarter is set in an underground realm rife with pollution and monsters. The object of the game is to get a certain character, who was genetically engineered into a walking pollution purification plant, up to the nature-y and now-pristine-and-human-free surface world, as the pollution will slowly kill her otherwise.
 * Notably, no one knows that the surface is pollution-free: the reason humans are underground at all is because the surface was ravaged and made exceedingly dangerous by some unspecified event in the past. The only things Ryu knows is that a) Nina can't survive in the pollution underground and b) the pollution gets significantly lower the closer to the surface you get. It's not until the very end of the game that people discover the surface is not just livable, but beautiful.
 * City of Heroes and its "expansionalone", City of Villains has a few zones that fit this trope. One example is the area previously named "Woodvale", but referred to in-game almost exclusively as "Eden". Here, the player can find many vistas of pristine wilderness trying to crawl its way back across a previously urban landscape. In a twist, all the nature hates humanity.
 * Not so much nature as a scientifically created Virus created by a Mad Scientist environmentalist. There's the spirit of a true nature guardian killed by them that helps heroes.
 * Ironically subverted in Eve Online - the New Eden system was initially a paradise, but was destroyed by the catastrophic collapse of the EVE wormhole. It is now a Crapsack Galaxy.
 * Mega Man X 5 had the crash of the Eurasia colony as the ecological disaster. Flash forward to Mega Man Zero 4, and with Dr. Weil now ruling Neo Arcadia with an iron fist, the dissenters are fleeing to Area Zero, a land made naturally pristine thanks to an environmental conditioning system left active after the crash. Area Zero is the hope of the people in that fragment of the timeline for a life free of Weil's influence; fitting his role as the Big Bad, Dr. Weil employs the Neo Arcadia militia to raze the area, up to and including manufacturing the Ragnarok Satellite for just that end; needless to say the whole point of the game is to prevent Area Zero's demise.
 * Tiberium Wars subverts it slightly. The first Blue Zone (think the First world) to be converted from a Yellow Zone (think Mogadishu with Toxic Phlebotinum added to the mix) is given the name New Eden. It is a subversion because it was a result of human (or more specifically, GDI) efforts and because it gets wrecked and is implied to revert to a Yellow Zone thanks to the Scrin blowing up Tiberium Deposits and using Tiberium-based weapons.
 * This is basically the Backstory of Armored Core, both the original PS 1 series and Armored Core 3 continuity. While it is never really explored in the first series, the third has the Raven (ie, you, the player) destroy a malfunctioning AI Administrator that controls your underground habitat. After doing so, a hidden subroutine made the AI open the gates to the newly healed Earth, the new Eden. That's the first game. Needless to say, due to the humans and corporations now left without any checks and balances going to the surface, the Earth gets worse progressively through the game.
 * In Mass Effect 2, the homeworld of the quarians is becoming this, after they all basically got kicked off their planet in a war with their creations, the geth, which also severely damaged the planet.
 * The Call To Power games allows you to CAUSE this, just faster. By completing the Eden Project, switching to a Ecotopian government and churning out Eco Ranger units, you can systematically wipe out every sprawling, polluting city in the world, replacing them (and the surrounding area) with pristine wilderness.
 * Ar Tonelico 2: Finally happen to Sol Marta after a long, tragic, desperate struggle; by way of the elusive Metafalica that everyone is after. Considering that this game can be described as It Got Worse: The JRPG, it's one of the most triumphant example of Earn Your Happy Ending.
 * In fact, New Eden is the goal of the entire series. The ending of Ar Tonelico 3 shows that Hope Sprouts Eternal and the entire planet slowly turning from dead brown into blue and green.

Western Animation

 * Adventure Time could be an example of this considering that it is after the apocalypse. A lot of places are pretty lush and colorful but some are in pretty bad shape.

Real Life

 * "An Earth Without People" was an article in Scientific American that addressed how likely this trope would be.
 * A recent television program was aired on the History Channel called Life After People which explored, in vivid CGI, what would happen to the world we leave behind if every human on earth disappeared.
 * The demilitarized zone between North and South Korean is a refuge for all sorts of plants and wildlife, simply because no human dare set foot in it for fear of getting shot by the other side (also land mines).
 * The same happened in the (former) border zone between East and West Germany.
 * In fact the whole border between the West and former Warsaw Pact nations is similarly undisturbed. The European Green Belt project aims to preserve it.
 * One theory claims that this was the reason why Europeans found the American continent near-empty and booming in wildlife. Not so much because it was better preserved (American fauna is in fact a lot poorer and less diverse than Old World fauna if compared to what it was before the last Ice Age) but because the previous generation of Native Americans had been decimated by European plagues advancing before the invaders proper.
 * A famous photographer snuck into the (US) Hanford Nuclear reservation to do a coffee-table book on the resurgence of nature in the heavily contaminated former nuclear-testing site, now off limits to humans, with similarly controversial findings. Similar photographic and natural studies have been done of Bikini Atoll, which is now teeming with fish thanks more to the absence of humans, since they are not considered safe to eat.
 * The city of Pripyat in the Ukraine. Despite the entire area being contaminated by radiation due to the damaged Chernobyl reactor, wildlife levels in the exclusion zone are at levels not seen since before the beginning of the twentieth century. It's called the Chernobyl effect. Radiation is bad for animals, but humans are worse.
 * That's actually heartbreakingly depressing. Humans are worse than nuclear radiation.
 * The Chernobyl Nuclear Exclusion Zone in Ukraine is now a wildlife preserve. As a result of the wildlife boom due to the absence of humans, "Radioactive Boars" are on the loose in Germany, wreaking havoc. Everything's Worse With Boars.
 * Shortly after the US entered WW 2, German u-boats began patrolling off the eastern seaboard. This made it extremely dangerous for fishing boats to go out, because they were effectively unarmed and likely to get sunk. The result of several years free of human fishing was that fish populations exploded. However, certain species have been so overharvested that scientists believe they will never recover.
 * Some of the most biologically diverse regions of the UK are actually in military training areas - because of the closed nature of these areas, as well as the strict rules the military have promoting rotation and protection (some parts of the training areas are even off limits to infantry and vehicles)