"what would happen if every human being on earth disappeared?" "[music] at some point in the future, this could be the fate of our planet this isn't the story of how we might vanish it is the story of what happens to the world we leave behind." "life after people" "the disappearance of humans may seem like science fiction, but eventually, there will come a day like this;" "a day when people no longer walk the earth" "it's no great stretch to imagine humans disappearing from the face of the earth." "every generation has its tales of armageddon or apocalypse." "we're the first generation that could, by deliberate actions, cause its own doom." "whatwilllifebelike afterpeople?" "we'retantalizedby ourmyths about our own destruction, but also tantalized by the notion," ""hey,maybe it's the turn of someone else."" "what will they do if we're gone?" "what will the earth do when i'm gone?" "it's the most natural question in the world" "[alarm buzzing] timehasrunout for man ." "our hold on the planet is over." "welcome to earth, population zero." "within hours after we're gone, lights start going out around the world." "more than 70 percent of power in the united states is generated by the burning of fossil fuels." "theplantwillonlycontinue to produce electricity as long as the fuel takes to be consumed." "if there's no one around to provide the new fuel into the generating plant, then it'll be quite quick before the lights start going out in cities all over the world." "nuclearpowerplants are unlikely to melt down." "the average reactor holds enough fuel to keep running for two years." "but without humans consuming the power generated by the plant, the reactors will automatically shut down into a safe mode in as little as two days." "evenwindgeneration can't last forever." "the turbines require bearings and lubrication of those bearings in order to keep operating." "if there's no one around to maintain the turbines, the electricity doesn't get produced asgeneratingplantsgodown , outages on the power grid contribute to a cascade of failure worldwide" "after a few weeks, the planet is plunged into a deep darkness." "it has not experienced since humans first huddled around campfires" "perhaps,the last glow of artificial lights on earth will be seen in the american southwest" "here,the mighty hoover dam hydropower plant takes little notice of the absence of humans." "its source of fuel is virtually limitless." "athooverdam, our fuel supply is actually the water in the reservoir in lake mead behind hoover dam, so as long as there's water in the reservoir, this power plant can keep running." "there's water in the reservoir keeps supplying the water to the hydro turbine generators." "these generators are operating automatically and that would continue as long as all of the systems are functioning normally." "if i and my staff were to leave tonight and not come back to hoover dam, say just in the condition of the plant is in right now, this would continue operating without us here." "that would still be true after about a week, several weeks,several months, maybe even a couple of years, everything would still be running normally." "in a life after people, it is possible that hoover dam would be one of the last power plants still running." "asthepowergoesout around the world, other systems are quickly beginning to fail." "beneathallthemajorcities, there's a complex network of underground tunnels, and these are there for drainage purposes or for cabling purposes, and in the case of the big cities, for transportation as well." "there are many of those sit below the level of the water table, and in order to keep them dry, we have to have a system of pumps that are switched on when necessary to drain the tunnels." "deepwithinnewyork city subways, more than 700 pumps constantly struggle to keep out a flood of ground water, an average of 13 million gallons a day." "now,ifallthesepeople were not around, there will be nobody to switch the pumps on." "it's estimated, that the tunnels will fill with water in about 36 hours." "[music] backaboveground, food is rotting on supermarket shelves." "home refrigerators become nothing more than cabinets for decaying food, but melt water from defrosting freezers may provide a temporary lifeline for some of the creatures we've left behind." "what will be the fate of our family pets once there are no humans left to care for them?" "rightfromtheget-go, there's gonna be a massive die off of dogs." "the instance that humans are gone, they're not creating the debris or producing the food that the dogs are living on." "he can't open cans, he can't get in the refrigerator." "they gotta get out of the house." "the family dog has gotta get out of the house or he's gonna die there." "and once he gets out, he's got to go to some source of food." "the first thing that happens is that they all jump out of the windows and they are now out there in a new landscape." "and the first to whack at it it is that they go back to scavenging a whole bunch of dead things out there in the world." "thereareestimatedtobe four hundred million dogs in the world and 300 different breeds." "but very few of them are suited to surviving in a life after humans." "the smallest dogs probably won't last a week without us." "there'sprobablyno niche for the smaller dogs." "dogs are very competitive and when you have wolves, they displace coyotes, coyotes displace foxes, and we would assume that hierarchy would prevail among domestic dogs." "infact, many of the unique features that have been bred into dogs over the years will now become major handicaps in the fight for survival." "therearedog for the really short legs, i think,the dogs with the really short faces or long faces,i think, that they're all doomed." "you know,they're not gonna move well, they're not gonna be able to search and explore." "i think that the kind of the middle of the spectrum, the kind of average dog, has the best chances in this." "i think that they will survive in the long haul, but it's not gonna be pretty." "asthesurvivingdogs struggle to find their new niche, household pests are slowly beginning to notice our absence." "little creatures, rats and house mice, they would seem to be able to exist without us are surprisingly quite dependent on our food supplies." "ratsandmice are usually termed" ""commensal rodents," which means that term means literally sharing the table." "they're very dependent on people." "and the little house mouse and norway rat are great examples of animals that would do less well in the absence of people." "intheinitialweeks after people are gone, they will raid pantries in homes,in grocery shelves in stores." "after eating through these food supplies, they will struggle to survive on things like cardboard,cloth, or glue." "ithinkthatifa city  was abandoned, the rats would have to go back to earning an honest living." "an honest living means to go back to the wild and compete for resources there." "eventually,theserodents will abandon homes and buildings, which will make them easy pickings for predators." "although,rats and mice will mostly likely survive in the future, their numbers will be greatly diminished." "after six months into a life after people, urban areas are already taking a turn for the wild." "thepredatorswouldreturn very quickly in the absence of humans because we suppress them, we create conditions that either work against them, or we deliberately go out, and remove and destroy them." "they would come back very quickly." "smallerpredators like coyotes and bobcats always survive on the fringe of human populations." "they are the first to colonize our abandoned neighborhoods." "larger carnivores will have to wait longer for the habitat to recover enough to support their appetites." "but soon enough,they,too, will hunt in what were once our backyards." "1 year after people one year into a life after people, towns and cities are still recognizable." "but nature is beginning to reclaim her old turf." "oneofthefirst great physical effects in the absence of people would be the transition of the impervious surfaces:" "the parking lots,the roads into places that supported and then had an abundance of plant life." "anyplace where you have sunlight that's hitting, you're probably gonna get some plant growth." "little seeds are gonna get stuck in the cracks and so forth, and these things are all gonna start to creep." "plants are wonderful that way." "they can destroy things in matters of,you know, a few years." "withouthumans to remove them, weeds like dandelions infiltrate every crack in the pavement." "as these weeds die, their remnants combine with ever-spreading moss and lichen to create a layer of topsoil." "this sandy soil is poor in nutrients, so only plants like clover that can pull nitrogen from the air flourish at first." "formerly manicured yards morph into fields for a white-tailed deer forage for food." "wild animals have also begun to find their way into abandoned cities." "man's supposed domination over nature has proven to be quite tenuous." "the signs of our vulnerability have always been there." "thisisan ailanthustree." "it seems to enjoy rooting itself in very inhospitable locations." "and it likes to attach itself to crevices in buildings." "and when it does so, it causes damage." "the roots expand, and the expansive forces of that force out mortar and stone and cause crumbling of a facade." "if you get a lot of this on an entire building facade, it could cause major,major damage." "asnaturebattlesback, even manmade goliaths like hoover dam aren't invincible." "to harness the power of this river took 21,000 men and five years of hard labor." "but one year after people, its 17 massive and seemingly indestructible generators are about to be brought down by an organism the size of a human thumbnail." "the lake above the dam is infested with an invasive species of mollusk called the "quagga mussel."" "this stealthy invader from eastern europe had no natural predators in north america other than the humans tasked with scraping it from the grates and pipes it colonizes." "themusselsattachthemselves to the inside wall of pipes and they're very prolific." "they colonize and rapidly build up and can grow on top of each other, and eventually completely block the diameter of a pipe." "thesmallpipes that bring cooling water to hoover dam's generators make perfect homes for these creatures." "and with no people around to remove them, they spread like a cancer." "andinfact, those mussels could clog up the cooling water pipes, to the point where we couldn't keep these generators cool anymore." "and it would cause the high temperature alarm in the automatic control system." "and that automatic control system would then start the shutdown sequence of that generator." "well,that would happen one by one for all of the generators of hoover dam, and eventually the entire power plant would be shut down." "inlasvegas, the last glimmers of manmade light on earth relinquish the night to its primeval blackness." "with the generators no longer running, no water at all is passing through hoover dam." "and the colorado river downstream begins to run dry." "on the other side of the dam, the water has nowhere to go and lake mead starts to rise." "itwouldjustkeep building up in lake mead." "and it would eventually gets to the point of spilling over through the spillways on either side of the dam." "unchecked, nature's most powerful elements reclaim their supremacy on earth." "triggered by lightning strikes, the wildfires that humans once battled so valiantly now rage unchecked." "cities and neighborhoods full of abandoned buildings, wild grasses,and debris are prime fuel for the flames." "chicago burns." "san francisco's stately wooden victorians are now only useful as kindling." "and just as it did in the time of the ancients, rome is burning again." "as structures burn to the ground, charred timbers release nutrients into the soil, providing the next wave of plant life, with the nitrogen it needs to grow and thrive." "five years after people, the roads of the world are disappearing beneath a green map that spreads like some relentless monster." "the advance of nature knows no boundaries." "the gates of london's buckingham palace are easily breached by vines and moss." "in moscow,red square is becoming very green." "inreality, nature will reclaim earth very quickly." "these stairs were cleared 18 months ago." "if we came back in another 18 months, we'd have a hard time finding them." "if we came back in five years, it would be almost impossible to find." "man'smasteryovernature has always been just an illusion." "when the cambodian city of angkor and its temple complexes were abandoned in 15th century, jungle trees grew indiscriminately over its stone structures." "entangling them in their roots." "now,without armies of gardeners and repairmen, modern cities are laid bare to nature's revenge." "in new york's central park, the great lawns,now untended, sprout with saplings." "five years without humans leaves the park looking more like a forest." "centralparkwillgobananas." "so all of a sudden you'll get trees, you'll get growth." "all the animals and plants that are there now will go up in population levels and they'll start to spread out into the city." "thestoryis thesame in washington d.c." "the great monuments have been swallowed by greenery." "and on what used to be the national mall, the sounds of the jungle are echoing." "zooanimals are really the great unknown." "depending on whether or not they could escape from their confinement, then things change dramatically because you might have lions, you might have tigers;" "both of which would be perfectly capable of surviving in a post-human period." "they'd do better further south than they would do in washington d.c." "but these are animals that are perfectly capable of figuring out how to do it and how to survive." "zooanimals may be the great unknown but there are things we can know for sure about life 20 years after people are gone because there's one spot on the globe where it's already happened." "[music] it's20years into a life after people." "without humans to apply fresh paint and fill in cracks, even concrete buildings have already begun to crumble." "lack of maintenance turns cities into eerie ghost towns." "animals that have long avoided human population centers now return to make new homes among the decaying walls." "how do we know this?" "because there's one place in the world where it's already happened." "we'restanding in the central square of pripyat,ukraine, the city that was once the most modern city in the former soviet union." "for 20 years now, this city has been sitting abandoned, and it really gives you a picture of what would happen if people are removed from a place of normal civilization." "evacuatedafter the chernobyl nuclear disaster, pripyat went from a city of 50,000 to ghost town overnight." "dust-covered school rooms remain as students left them just over 20 years ago." "vegetation pries apart masonry as it crawls over buildings." "an amusement park scheduled to open four days after the date of the accident remains never used." "the park's ferris wheel accumulates rust rather than riders." "the bumper cars sit in a state of motionless decay." "pripyat has provided an amazing and rare opportunity to see what happens to a manmade city when humans disappear." "icansee from my geiger counter that it's really quite safe to be here, radiation levels were not very high." "but you can see that we've really hit a point of no return in recapturing these facilities." "we're in what was the cultural center of the city of pripyat." "and indeed,this was a place where friends gathered, where there would be celebrations, there would be balls, there would be music, there would be dancing, there would be performing on the stage here behind me." "but after 20 years, the forces of nature have started to decay this facility." "thisconcretesovietfacade may look imposing but it's no match for the frigid ukranian winters." "as the temperature drops below freezing, water that has accumulated in cracks,expands, exerting bursting pressure that pulls apart the masonry." "as vegetation grows unchecked, the roots spread through foundations and stairs." "these roots suck in moisture that makes them expand and grow." "like miniature hydraulic jacks, over time, they slowly push apart the concrete." "thisisonly20years." "can you imagine what this facility will look like after 200 years?" "aftertheaccident, scientists expected the worst for the wildlife in the region." "most of the trees in a 1 1/2 square mile area around the nuclear plant were killed off by radiation." "many animals died." "but incredibly,the effect of the absence of humans for 20 years has outweighed the initial damage caused by the nuclear nightmare." "thisisthered forest, an area that was horribly impacted by radioactivity due to the chernobyl explosion." "and the trees that you see around me were killed by the radioactivity." "the original amounts of radioactivity were sufficient to kill all of the wildlife in the region as well." "but now we see a resurgence of the wildlife." "as an example of how wildlife has prospered here, we see,here,we have an antler from a red deer and,obviously, a fairly large and healthy red deer." "red deer are hardly found in any other areas in this region and the chernobyl zone is the only place that you'll find populations of red deer." "we also find russian wild boars that the populations in the zone are 10 to 15 times higher than they are outside of the zone." "[speaking russian] we'renowat thekindergarten of karpachi village,not far from the chernobyl station." "children were living here while their parents worked." "but after that night in april 1986, they never returned." "we are in what was formerly a bedroom in this kindergarten where children used to sleep and rest." "now,there's a certain emptiness here." "all these windows are broken." "but the room continues to live on." "birds fly in here and sit on these bars." "we even found evidence that an owl comes here." "an owl,it regurgitates food, fur,bones,and feathers." "evidently,it likes to sit here on this window pane." "so this room continues to maintain life." "even trees which had proven especially vulnerable to radioactive fallout." "are finding new homes in the evacuation zone." "i'msitting in the pripiat soccer stadium where,20 years ago, hundreds of people would come and cheer on their favorite team." "you can imagine the laughter of the sounds of the crowds here." "the activity on the field which,20 years later, is barely discernable." "the soccer field now is going through succession as you would expect in returning to what it was originally hundreds of years ago which was a mixed deciduous forest." "igrewup in atown about like this and i used to enjoy riding bumper cars like these about a half a world away." "and it seems pretty sad when you look now and you see what's become of this beautiful city of pripiat and that people will never live here again." "but there's another side to this story, a very encouraging side;" "one that says that life is much more resilient than what we thought possible." "that in the absence of man, that life will continue and that life will thrive and that the legacy of life will always be here, because we are a part of life." "even if we disappear, our legacy of life will continue." "[music] it's 25 years into a life after people" "out in the country nature is beginning to erase all evidence of man" "in the suburb packs of fellow dogs roam through decaying neighborhoods in search of their next meal." "in some of the great cities of the world, solid ground is getting harder to find." "in the time of humans, london was protected from tidal surges by 10 retractable steel gates that could be raised during storms to seal off the thames river from the north sea." "without humans to operate the barrier, london is defenseless." "another low-lying city, amsterdam, meets the same watery fate." "in a new york city high rise, some windows have already cracked and slipped loose from their frames and many more are on the verge of destruction." "after a quarter century of exposure to moisture and heat without maintenance, the normally flexible window sealant has become rigid, locking this window to its frame." "as the metal frame expands and contracts with changes in temperature, it induces stresses on the glass." "it cracks and plummets to the sidewalk below." "aftera fewof thewindows fall out of a building like this, then the wind pressure effect changes dramatically." "as well as external pressure coming on to the building, you also get suction." "and that aggravates the problem so more of the panels are likely to fall out." "throughthesegapingholes, the building fills with windswept debris." "a summer storm rolls in." "on top of the structure, the copper-lightning deterrent system that once protected thousands of office workers is now corroded and useless." "a lightning bolt turns the tower into a raging inferno." "the gutted building makes the perfect home for a surprising survivor." "although pigeons once relied on the handouts of humans, they have done just fine in 25 years without us." "pigeonsaresurvivors." "they can live in the wild;" "they do live in the wild still." "and in a period where there were no people but there still were edifices and artifacts,our buildings, they would do very well because they would adopt these as kind of artificial cliff faces, which is what they really are" "adapted to." "likethepigeon, the disappearance of humans forced a change in the habits of the lowly cockroach." "thinkofthepoorcockroach after they gorge upon our surplus when we're gone, they'll mourn us." "they'll be sorry." "butthemorningwon 'tlast for long." "while cockroaches thrived on our scraps, they can also eat bookbindings, and cardboard, and any rotting organic matter including dead leaves and roots." "while food isn't a problem, roaches also need warmth;" "the kind that humans had always supplied through artificial heat." "cockroaches started as a tropical species and some experts say they couldn't survive the winter in colder cities." "but it's hard to bet against a creature that has seen the dinosaurs come and go." "cockroachesare extremely adaptable." "they've been around for 300 million years." "if i have to bet, i'd put my money on them being able to survive in one form or another." "thefirstwinter after humans did witness the die-off of some cockroaches, but many more moved underground to find warmth until milder temperatures returned." "in an abandoned downtown devoid of insecticides, overrun by vegetation and with a rising water table, this former pest is now enjoying a golden age." "cockroaches were only a nuisance to humans, but wolves were a terror." "so man hunted them mercilessly." "when the first european settlers arrived in what is now the united states, it's believed nearly half a million wolves roamed the country side." "by the 20th century, these predators were nearly extinct in the lower 48 states." "now,with no humans left to battle them, wolf populations multiply by as much six times each year." "within 25 years of our disappearance, there could easily be half a million of them roaming the united states again." "this amazing comeback has been seen on a small scale before." "in 1995,biologists released a few dozen wolves within the boundaries of yellow stone national park;" "a place where they would be protected from persecution by humans." "within a decade, a few dozen had multiplied into 1,500 and the wolves quickly spread out from their release point to occupy territory throughout the states of wyoming,montana,and idaho." "itwouldbe fast if you can start with just a few dozen wolves and in the course of one decade, have a population of 1,500 and you could have a geographic expansion where they filled up a big chunk" "of a three-state area." "and these are big western states." "yeah,when the conditions are right, they can re-colonize pretty rapidly." "could we see them in manhattan or chicago?" "as soon as the deer get there, the wolves will be right behind them." "animalshaven't just been hunted by humans;" "they've also been hemmed in." "there are roughly three million miles of paved road in the united states alone." "and it's no coincidence that many of them cut right through the paths animals use to get from place to place." "thethingsthatmake a landscape good for animal movement also make it easy to engineer a road in that location." "so,we've cut off pretty much all major migrations in north america." "asphaltandautomobiles wreaked particular havoc on the grizzly bear." "their habitat was so carved up by roads that they're confined to isolated pockets, cutting them off from food sources and potential mates." "in a life after humans, roads are no longer barriers for the grizzly." "instead they are pathways;" "trails that lead them back into the heart of their former range." "fortyyearsafterpeople." "while cities of steel and concrete are still standing tall, the suburbs are under attack." "roughly 90 percent of all homes in the united states have wood frames." "while some have burned, others are now being devoured." "without paint and preservatives, the lumber of homes is defenseless against termites." "termites feast on cellulose, the basic building block of wood." "and their appetites are relentless." "some colonies can eat as much as 1,000 pounds of wood per year." "in this destructive advance, the termites aren't working alone." "theprocesswe know as rotting will occur when the wood gets exposed to the elements." "and this rotting,actually, is a more complicated process." "it's a process by which microbes attack the wood and release carbon dioxide and methane to the atmosphere." "if humans were to leave, it'd be a matter of decades before most structures that had significant wood components would start to decay." "facedwith a two pronged attack from termites and rot, the beams that hold up the roof give way." "and the boundary between inside and out, that had once been so important to the humans who called this building home, is forever erased." "othersubstances like this mortar and rock are gonna last longer than several decades, but they'll still crumble after natural,chemical, and physical weathering processes, and eventually these walls will fall down as well, and there'll be no remnants." "now,naturewillactquickly to swallow up these ruins." "this crumbling house in baltimore's druid hill park was once home to the caretaker of the city zoo." "itlookslikethisbuilding has been abandoned for more than a hundred years." "but in reality, people have been living here up till 40 years ago." "it's amazing how quickly the vegetation has reclaimed the area." "the vines have started to climb up the walls." "the trees are growing into the structure, and they're both physically pulling the structure apart, and chemically dissolving it." "structuresbuiltentirely of stone or masonry will far outlive anything made of wood." "exactly how fast they will crumble depends on their environment." "thecoastof maine,really, isn't very kind to buildings." "structures out here don't so much decay when you live them alone;" "they melt." "thesestructures on black island,maine used to be part of a granite quarry whose stone was used to build and decorate cities like boston,new york, and philadelphia." "it was abandoned around 1920." "here,thebuildings have all vanished within the space of 80 and 90 years." "there's almost nothing left." "intherightconditions and with human maintenance, stone construction can last for thousands of years." "in some places in europe, ancient roman aqueducts are still in use." "but without maintenance, stone can fall victim to a very stealthy enemy." "oneofthegreatenemies of stone is actually salts and salt crystals." "even thousands of years ago, people notice the effect that salts had on deteriorating the ancient pyramids." "therearemanyways salts infiltrate stone buildings and monuments:" "polluted air,seawater, and even bird droppings." "solublesaltsdissolve in water, and as the water evaporates, it will rise up inside of porous building materials;" "things like brick and stone and even concrete." "and what happens is the salts will continue to grow inside the pores of the stone until they come up against the side of the wall, and they'll actually push the stone apart." "whatwe'reseeing in this time-lapse video really shows the rapid decay of the stone in response to this deterioration by salts." "in this experiment, it took about three weeks to go from this piece of stone to this piece of stone, which is completely deteriorated by sodium sulfate crystallization." "threeweeksin this accelerated aging chamber are equivalent to a few years in the harshest of environments, or a few decades in a more benign desert climate." "ifwecouldsee  microscopically what's going on inside the pyramids, this is what would be taking place." "you can actually see the salts deteriorate the stone." "althoughnotimmunetodecay, the pyramids have survived for nearly 5,000 years because of their sheer volume and their hot, dry desert environment." "too massive to be destroyed by either man or nature, the pyramids of giza were the only one of the seven wonders of the ancient world to survive into the modern era." "many ancient monuments have survived only because of human maintenance throughout the centuries." "the sphinx was uncovered and restored for the first time back in 1400 b.c." "modern experts who have studied the sphinx,predict that without human intervention, deterioration from salts and wind erosion could render it a pile of dust within 500 to 1,000 years." "the largest concrete structures like hoover dam,will last even longer than that." "hoover is so thick that over 70 years after it was constructed the concrete deep inside was still curing." "but of the 15 tallest dams in the united states, only 10 are concrete." "the others are made of compacted rock or earth, like northern california's trinity dam." "if there were humans around, this leak in the dam would get an emergency fix." "but those days are long gone." "someofthesedams are absolutely enormous." "and if they fail, as they will in time, then the surge of water that falls in behind them and cascades down a valley below would have a huge force, big enough to sweep away everything on its path." "fiftyyearsafterhumans, the strain of neglect is beginning to show on even the best design of manmade structures." "everythingthatmandesigns carries within it,the seeds of its own destruction;" "that includes bridges and buildings." "the brooklyn bridge, one of the most famous bridges in the world for over 125 years." "the reason that bridges last so long is because engineers look after them." "they inspect them regularly, they maintain them, they paint them, they replace pieces that need to be replaced." "without people, without engineers, the deterioration process will accelerate dramatically." "themostvulnerableparts of a suspension bridge are the steel vertical hanger cables." "thesehavebeentested in the laboratory, unfortunately not on the bridge, but what you see is a classic kind of a failure that occurs in these wires." "these are the individual wires, all right?" "that's an individual wire." "that probably has a tensile strength that's maybe 200,000 pounds per square inch." "that's a very high strength steel." "asstrongas theyare , these cables have a fatal flaw:" "it's the stuff they're made of." "steelisamineral that comes from the earth that's mostly iron, so it's probably" "95,98 percent iron." "exposedtomoisture in the environment, iron will start to revert back to the minerals it came from." "ashes to ashes,dust to dust." "it'sgonnago backhome." "it came from the earth as iron oxide of some form, and it's gonna go back." "thisistheprocessweknow as corrosion, and you see it wherever steel is exposed to moisture." "theenemyof steel is corrosion." "the problem is keeping the water out." "part of that is maintenance." "if you don't maintain them, you will get corrosion." "completedin1883, the brooklyn bridge cost" "$15 million to build." "over the last two decades," "$3 billion have been spent maintaining it and the other bridges over the east river." "in the time of humans, the brooklyn bridge was continually maintained and fully repainted, roughly,every dozen years." "while across the country in san francisco, the golden gate bridge was protected at all times by a vigilant brigade of 17 iron workers and 38 painters." "whatdotheydoallthetime?" "they will tell you,"we paint this bridge continuously."" "what happens when that stops?" "i can tell you what happens when that stops." "the cables begin to rust, the paint peels off, the wires begin to break, and they'll come to a point when the bridge is gonna come down." "seventy-fiveyears after people." "most of the 600 million cars that once traveled the roads of the world are now just rusted remnants of the human past." "abandonedcarswillbehave differently depending on the environment that they're in." "a car left in the mojave desert, for example, is gonna last a long time." "a car abandoned in my native scotland is gonna have a very different fate." "any cars in a coastal environment with salt in the atmosphere, they might not last more than 20,30 years." "tiresdeflate within a few years, although the rubber and synthetics they're made of will remain intact for centuries." "paint deteriorates quickly." "and once it flakes away, rust corrodes the car's body at a rate of 5,000ths of an inch per year." "seventy-five years after humans, most cars, even in the most forgiving of environments, will be reduced to skeletons." "after a century,the family car is a barely recognizable heap of metal." "it's now 100 years into a life after people." "the brooklyn bridge, which had stood for over 125 years with people, can't survive even a century without them." "as the cables fail, the deck and railings begin to warp and sway." "the deck pulls free, and the roadway spills into the east river." "asanengineer, it's very sad to contemplate that this beautiful iconic structure has got an end to its life." "but without maintenance, an end to its life it certainly has." "howexactlydo bridgesfail?" "once corrosion starts, the wires begin to crack." "andthewire doesn't have to have a very big crack before it breaks." "maybe a third of the way through." "you may wonder what happens when they fail." "how do they fail?" "do they just break and what do they do?" "and the answer is they tend to shred and fail, with individual strands starting to fail and then,kind of,cascading, and a whole series of wires then begin to break." "asuspensionbridge like the golden gate can survive the weakening of one of its vertical cables." "but once two or three start to go, the whole bridge is in jeopardy." "twisted steel crashes into the waters below." "it'sgonnabe gone." "two hundred years?" "i doubt it will last 200 years." "the bridge is gonna be in the drink." "[music] ifsome of our largest structures have already failed after 100 years, can there be any hope that our civilization will leave a permanent mark after we're gone?" "what will remain of the records of our history and culture a hundred years after people?" "ourvaultscontain our most precious materials, and their biggest enemies are temperature and humidity." "as long as their long-term storage is kept at these very controlled settings, we feel assured that the materials will be lasting a long time." "stored under ideal conditions, paper and film both have an estimated shelf life of 200 to 300 years." "but expose them to the rigors of an uncontrolled environment and that lifespan is cut at least in half." "ifallthepowerwent off,  probably within a week, we'd see very big spikes in the temperature and humidity." "inthishostileenvironment, cellulose acetate, the most common material used for films and photographs throughout the 20th century begins to bubble and warp." "all of that culture and history, from the landings on d-day to hollywood films and even your cherished home movies and photographs, won't last a century without the care of humans." "so,thosepreciousimages, given time, are going to end up like this." "all of these are examples of various stages in the decay of cellulose acetate-based film exposed to very high amounts of humidity." "essentially, these materials are finished." "inlibraries, the great repositories of our collective knowledge, the damage comes from microscopic invaders." "although we can't see them, mold spores are on all the surfaces around us,lying dormant, biding their time for the right conditions to strike." "high humidity creates the right conditions." "andso, the situation is set up for the mold to really boom." "somebooksanddocuments will avoid this fate." "the dead sea scrolls survived 2,000 years in caves in the judean desert, owing their longevity to the arid climate and lack of damaging sunlight." "but these are rare exceptions." "sowithout human intervention, a book like this might last, at best,another hundred years." "[music] evenourdigitalmedia won't last forever." "estimates for the lifespan of cds and dvds range from a few decades to a few centuries under ideal conditions." "weknow about the ancient egyptians because what they left behind was engraved in stones." "[music] our form of capturing knowledge, information,our history, our advancement is typically either in a computerized form, in a cd,or in a printed paper like this." "what we have here is something that will degrade over time." "it will not last for thousands of years like what the ancient egyptians left behind." "itseemsprettyironic that with all of our advances, we still have not come up with anything as durable as clay tablets and stone tools." "[music] 150yearsafterhumans, the subways that had started to flood in the first 36 hours are now flowing subterranean streams." "the beams and archways that hold up the roofs of these tunnels are on the verge of collapse." "now,thesetunnels are not far below street level." "these columns are supporting not just the roof of the tunnel, but the street above." "and in time that these tunnels are inundated, flooded with water, corrosion will start to take hold and we'll start to see collapses." "thetunnelsecho with the sound of cracking steel and cement as the streets above are sucked into the underground." "[music] above ground,life in the city is once again bustling." "vines have grown up the sides of abandoned skyscrapers, adapting to feed off rainwater that pools in crevices and on ledges." "thesevinesallstartup." "and the vines have little branches." "it'd be nice if they produce a fruit or something that was edible." "you gotta have a plant with some fruit or,you know, some source of energy for animals." "and then you would get this vertical ecosystem out there,and you would get birds nesting in there." "you get things hunting in through there." "you could have snakes there." "you could have all kinds of things." "asinsects and smaller animals get established, cats move in." "andthere'ssome interesting examples of that around the world." "if you go to the colosseum-- you just look in it-- it's just loaded with cats." "and the old tombs and old catacombs and so on get loaded with cats that use this as a living space from which,then, they radiate out during the day." "thesefelines are the descendants of our former house cats." "immediately after people were gone,they replaced their human-supplied diets with field mice and small birds." "hunting out in the open was hard work." "but up here, the pickings are easy." "now,they live their whole lives high above the city, finding all that they need to survive without ever having to touch the ground." "they are the kings of the new high altitude food chain, with million-dollar views of a bizarrely altered cityscape." "icouldpicturenew yorkcity  with all the buildings covered with vines,you know?" "hawks sailing around." "it'd be lovely." "it would be absolutely lovely." "[music] forcats, life in this new environment could eventually lead to some strange adaptations." "isuppose,ifyouwanted to be really imaginative about it,you could say that, eventually,they could be like flying squirrels and so on." "they could glide from places." "the possibility is always there for some imaginative responses to this unusual environment." "whilesomecats have made a great leap forward, many dogs have reverted to the ways of their ancestors." "some that have interbred with wolves now fall in packs to bring down larger prey." "[music] ithinkourdogs, as placid as they may seem when they're in our homes lying on the living room floor, still posses the instinct to survive, enough that they would be able to do whatever it took" "in bringing down prey in order to live." "[music] 150yearsafterpeople, the oceans are teeming with life." "the creatures of the sea have welcomed the disappearance of mankind." "historically, we've treated the oceans in two strange ways at the same time:" "a pantry and a toilet." "and over time, our ability to damage the ocean has grown and grown and grown." "withhumansno longerfishing and polluting the sea, the path was cleared for this astonishing recovery." "it has happened before." "during world war ii, allied fishing trawlers avoided the north atlantic, and populations of fish there skyrocketed." "inhere,thebasicbiology of these kinds of animals is working in our favor because animals like this sunfish can produce millions of offspring in a year, much more than an equivalent-sized terrestrial animal like a cow." "and because of that prodigious potential to reproduce, the oceans could come back pretty quickly if the human population were suddenly to disappear." "researchhasshown that in the 18th century, before the havoc caused by humans, the oceans were capable of sustaining massive amounts of life." "somanywhales that they stink up the air;" "so many tunas that they froth the ocean;" "so many turtles that you could walk across the sea on their backs." "so,if people were to vanish off the face of the earth, then that's the kind of ocean it could be." "[music] seagullsarealso flourishing,but it has been a treacherous flight." "the abundance of food from humans had allowed gull populations to explode beyond what nature could normally support." "wehumans are pretty messy species." "and for a very long time, we had open landfill dumps where,as far as we were concerned, all the stuff that wasn't fit to eat was just thrown out." "but from the gulls' point of view, this was an amazing free lunch counter." "so,you had a lot of birds that probably wouldn't have made it through their first winter if they've had to feed for themselves." "suddenly,they had all these free food available to them." "an immediate consequence of a world without people would be some very hungry gulls who would be very voraciously looking for other things to eat." "afteraninitialdie-off, the remaining gulls took advantage of the recovering oceans, where plentiful schools of fish erased any memories of the human-manufactured feasts they used to enjoy." "two hundred years after people, from new york to chicago, seattle and paris, our iron and steel icons are on the verge of collapse." "while it has outlived our great suspension bridges, the eiffel tower is not invincible." "in the time of humans, its iron superstructure was painted once every seven years to protect it from corrosion." "in both age and structure, the eiffel tower has a lot in common with the 300-foot high kinzua railroad viaduct in pennsylvania." "wasa bridge that was wrought iron originally." "it was reconstructed about the turn of the century in steel." "and what happens here of course is that unless it's maintained, corrosion occurs." "and what happens with the corrosion?" "the connection points freeze up." "they are not allowed to move." "and here are some pieces from that viaduct." "you can see that there's corrosion all over the place." "that's no longer steel." "astructure with frozen connection points can't absorb the stress of high winds." "eventually, in this strong wind storm, it literally fell over." "section by section, piece by piece, it fell over into the valley where it had spanned the valley for over a hundred years." "just not maintained." "you can think of many structures that are coming from that same era like the eiffel tower, its iconic structure." "that doesn't shield it from the fact that's it in a corrosive environment." "and so in time if you do not do anything for that structure, it will fail." "and it will come down." "thetimebetweenone  and 300 years after people will likely be the era of the great collapses worldwide." "in seattle, the iconic space needle was designed to sway one inch for every 10 miles per hour of wind, but with its steel weakened by corrosion, it takes little more than a strong breeze for the symbol" "of the 1962 world's fair to crash down from the skyline." "when humans disappeared, sea levels were already on the rise." "in manhattan, over the centuries, saturated soil around the empire state building's foundation pilings have allowed the building to lean." "oncea buildingstrays from the vertical, then gravity forces are also acting against the structure, increasing the stresses at the base of the building, now we're unlikely to see a skyscraper fall like a tree in the forest." "once it does start to incline, gravitational force will cause the top of the building to collapse downward on top of itself." "decayhasalsoovertaken the city of chicago, the birthplace of the skyscraper." "the sears tower, the tallest man-made structure in north america, has reached the end of its reign." "the first 500 years after people has been an era of decay and destruction." "our concrete structures have lasted the longest." "the ancient romans invented the first form of concrete." "and some of their structures remained intact for over 2,000 years." "but modern concrete isn't nearly as durable." "it has a higher water content and is more loosely packed, which leads to more air pockets and cracks." "modern concrete structures have another fatal flaw." "belowthesurface of reinforced concrete structures, there is a mesh of steel reinforcing bars and they don't corrode because the concrete maintains an alkaline environment around them." "now,when that alkalinity breaks down, as it will in time, then the steel will start to corrode." "asthesteelrebarrusts, it expands to three times its original volume creating an outward pressure that causes the concrete to crumble." "inverybroadterms, after 50 years we'd start to see surface cracking on concrete." "after a hundred years, flaking of the concrete surface." "after maybe 500 years, most reinforced concrete structures will be gone." "welookat theseimages of our fallen civilization, it helps us to identify with the past, with the greeks and the romans, with the crumbled mud brick cities of ur." "each of us knows that our bodies are going to fall apart;" "why not our cities too?" "athousandyearsago , 6 1/2 billion people called this planet home." "at the early 21st century, more than half of them lived in cities." "now those cities are unrecognizable." "aftermaybeathousandyears or so,the scene behind me would be very,very different." "there'll be very little evidence of buildings, very little evidence of the activities of man." "what we would see would be a jungle of vegetation." "thefutureof cities in a life after people can be best imagined by looking to the past." "thisisminettastreet in greenwich village." "most new yorkers might come here and wonder why it curves like this." "it curves because once upon a time there was a stream here, and then a brook." "there were more than 40 streams on manhattan island." "all flowing down and carrying the rainwater down to the sea." "so what happens today, the rain falls,the snow melts, but it flows right along the street and down into that storm drain there." "if there weren't people here anymore,there'll be no one here to maintain the sidewalks and maintain the streets." "they'd start to crumble up." "they'd start to break apart." "trees would come back, vegetation would come back, and eventually the hydrological cycle would reestablish itself." "and who knows, maybe minetta street might once again become minetta brook." "usinghistoricmaps and computer modeling, scientists with the manahatta project are rediscovering what manhattan island looked like when explorer henry hudson first sailed around its shores in 1609." "hereweareinfoleysquare, the administrative center of new york city and location to the famous courthouses you see on tv." "this place hasn't always had such colossal buildings and stony streets." "once upon a time,400 years ago, the collect pond was here, the freshwater source for new york city." "right behind me, there was a stream that drained down to the hudson river shore, another stream to the east river." "and there was this beautiful pond that was nestled in an amphitheater of hills." "so what would happen if all the people were to disappear?" "the buildings, they would tumble down." "the soil would start to reform." "trees would start to grow out of them." "they would become the new hills, the new amphitheater around this place." "nature would reestablish itself and slowly bring this place back into the green heart of what it means to be here on planet earth." "newyorkcity, like the rest of the planet, has changed radically." "the transformation is most shocking in times square as the once beating heart of the city is silenced by nature's onslaught." "it's 10,000 years after people." "could it be possible after only 10 millennia that humanity has vanished without a trace?" "human scientists once predicted that our history and culture would live on through our radio and television broadcasts, which carry on through the universe toward the infinite, perhaps to be tuned in by an intelligent species on a distant planet." "somepeoplethink that there's an expanding shell of radio and television from earth,expanding outward alerting the universe," ""here we are and this is our culture."" "unfortunately, recent calculations by of all people,the seti, search for extraterrestrial intelligence group, has shown that all of this dissipates within one and two light-years into noise." "ifthisis true, our signals won't even make it out to the newest star beyond the sun." "so what will remain 10,000 years after people to tell the story of the once great civilizations that walked the earth?" "iron corrodes, concrete crumbles, wood and paper decay." "still,some of what man built on earth remains." "the most colossal of our stone structures like the great wall of china have aged like mountains, subject to erosion, but at such slow time scales, they will still be recognizable in some form for eons." "the great pyramid at giza is so massive that it lasts long enough to be swallowed up by the desert sands." "the hoover dam built to be as tough as the canyon walls around it is one of the last man-made structures still standing." "but now thousands of years in the future, earth is about to be visited by the last of the great collapses." "it'stheenvironment that eventually wins." "earthquakes,sandstorms,rain." "but there are a few exceptions." "i would have to say that mount rushmore, carved out of solid granite in an ecologically stable place, the only enemy it has is wind-driven pellets of rain." "i think that mount rushmore may be around a hundred thousand years, possibly 200." "possibly even in time to be looked at in awe by the earliest of our replacements." "andwhoor whatmight those replacements be?" "perhaps chimpanzees might somehow make the leap." "butwehavetoconsiderthis:" "some scientists believe that it's easy for nature to bring animals up to a clever level where they might use tools, they might become masters of their environment." "but the leap to being able to stare at the sky and imagine a cosmos, to be able to contemplate yourself, to be able to contemplate your own role in the earth, this may be a leap that was a sheer accident" "for humanity." "in which case, you're not talking about a complete recovery." "you're talking about a planet that may continue, but nobody to talk about it, nobody to think about it." "ifearth's4.5billionyearsofexistence were condensed into 24 hours, the passage of 10,000 years would be a fraction of a second." "man's time on the planet so far would be about half a minute long so,like an abandoned village on a global scale the earth will move on without us there was life before people." "there will be life after people." "resync by Santa aka Snt, 2009"