Present Tense/Shane Hegarty:In the Belarusian city of Pripyat, abandoned after the Chernobyl disaster 20 years ago, nature has reclaimed its territory. Wolves roam the streets; lynx, elk and bears stalk the motorways; plants widen the cracks of the concrete buildings. The forest has eaten up avenues and smothered entire tower blocks.
If you have wondered how long the remnants of mankind would survive if we were to somehow suddenly and totally disappear from the earth, Pripyat has proven a chastening model of just how unsentimental Mother Nature is. According to an analogy, if the entire life of the universe could be compressed into a year, mankind would only have walked in the door six minutes ago. On that scale, were we to disappear tomorrow, almost all trace would be gone in about the time it takes for the cosmos to have lunch.
A recent New Scientist article went into the disconcerting detail, explaining that in a short space of time a future intelligent species, or passing alien, would have to look very hard to find any evidence of our having been here at all. The London Times followed up by putting humanity's destiny into apocalyptically snazzy poster form - a cut-out-and-keep timeline of our species' futility.
If Homo sapiens vanished overnight, most of the man-made pollutants, though not all, would disappear within weeks. While light pollution currently means that nowhere in Germany, for instance, is truly dark, electricity generators would quickly whirr down.
Meanwhile, animals would steadily move back into the urban landscape. Fish stocks would eventually return to full levels, as happened during the second World War, the last time mankind stepped back from large-scale fishing. And, thanks to interbreeding, dogs would return to a hardier state. As one expert asks in New Scientist: "If man disappears tomorrow, do you expect to see herds of poodles roaming the plains?" What a sight that would be. As would massive packs of Shih Tzu sweeping across continents, chased by yapping masses of Scottish terriers.
In 50-100 years, most city streets would be overgrown, and man-made structures would soon degrade. After 200 years, most bridges would have collapsed, with those nice glass ones that have grown so ubiquitous being the first to go. Within 1,000 years most buildings will have collapsed. About 50 years after that, Michael McDowell's ego might finally have diminished to only trace levels.
In 500 to 1,000 years, most organic landfill waste will have decayed, the last stragglers presumably being half-finished Pot Noodles and the leftovers from a Chinese takeaway I had in 1993. Some plastics will stay on for many thousands of years after that, and glass will hang around for a while too. Some paper is also likely to survive long after the sophisticated technology has rusted away, so posing the horrendous possibility that while much of our modern wisdom will vanish, a future race will still be faced with having to read endless articles about Seoige and O'Shea.
It will take the carbon dioxide we've belched into the skies 1,000 years to return to pre-industrial levels, with the sea absorbing the rest over subsequent millennia. However, our radioactive waste will have the impertinence to hang around.
Apparently, it may be two million years before some of that waste has returned to a safe level. It will be the fart that humanity leaves behind in the room.
So, that's it. A few bones and bits and pieces aside, we'll be noticed for having dirtied the place up a bit. If we are noticed at all. It's a wonder that the collective will of mankind doesn't take a slump at such a realisation. That mankind doesn't stay in bed all day, rising occasionally only to howl at the pointlessness of it all and to stick another Pot Noodle in the microwave.
It is bad enough to have your own, deep well of existential angst of how even the act of passing on of your genetic material is only the addition of a grain of salt in the ocean of mankind. At least there was some comfort in looking around at the achievements of humanity: architecture, art, writing, some of the television that isn't Seoige and O'Shea and thinking, well, at least you were a part of that. And that would surely last. Only it turns out that we could build a tower block the size of Leitrim, and it could be gobbled up by Roscommon by the time the century was out.
And yet, it occurs to me that there is hope. The moon harbours evidence of our once having been there and it's not so easily covered over. NASA estimates that the astronauts' footprints could last a million years in the windless, dead landscape. The flags should last longer, as well all the other bits of spacecraft and a couple of golf balls that would pose interesting riddles for passing aliens.
And Sweden, rather bizarrely, announced this week that it plans to put a traditional red cottage on the Moon by 2011. So, it turns out that in millions of years' time, aliens may actually have some bed and board while they marvel at the achievements of a long extinct civilisation and figure out which way up the Ikea instructions should be held.