I was reading an interesting chapter from "The World Without Us" by Alan Weisman last night. The book is based on a thought experiment examining how man-made infrastructure (e.g. cities, dams, petrochemical refineries) and ecological impacts and interventions (e.g. modern agriculture, plastic pollution and nature preserves) would hold-up if humans were taken out of the equation (aliens abduct us or the rapture comes down and we've all been really good).
One of the key takeaways from the book is that most things don't get beyond 10 or 20 years before degrading significantly, often collapsing and subsequently being colonized by various forms of life (bacteria do the dirtiest work, eventually evolving to eat things like petrochemicals). Some of our seemingly most invincible industrial sites are some of the most fragile.
The things that will be around the longest? Plastic and Mount Rushmore. The chapter on plastic has inspired our household to forgo as much plastic as possible in our daily lives (more on that effort in another post). Plastic does not biodegrade - literally every scrap that has ever been produced in history lives-on somewhere in some form, either as buried plastic bags in landfills or as tiny particles of plastic bobbing in the ocean, working their way up the food chain. It's a legacy that suddenly makes a plastic wrapped sandwich or plastic take-out fork look a lot less appealing. As for Mount Rushmore, the ancient granite carved with the faces of presidents erodes one inch every 10,000 years, which means remnants of the sculpture should be around for seven million years or so.
The subject of the chapter I was reading was the Demilitarized Zone (DMZ) between North and South Korea. The zone is 250km long and 4km wide. In addition to being closely guarded on both sides by hundreds of thousands of soldiers armed to the teeth, the area is strewn with landmines, ironically making it one the safest and most "natural" places in Asia for endangered species like the red-crowned crane (pictured above). One third of the remaining 2500 cranes depend on the DMZ and nearby Civilian Controlled Zone (CCZ) as their only sanctuary on the Korean peninsula. Because the zone has been free of human intervention since the early 1950's, it's in a relatively pristine state, with some hoping that a few of the world's all-but-extinct Siberian tigers might still call it home. Like other nature preserves, Weisman sees the DMZ as an ark of sorts, a place where if conditions were right, biological diversity would spring forth and begin colonizing the rest of the peninsula if human influence was removed or reduced.
Despite the landmines and more than a half-century of hatred and military incidents on both sides, many think that Korea will one day be reunited and that the DMZ could be up for grabs, easing housing pressure in cities like Seoul and making real-estate developers' dreams come true. Others think the DMZ should be left as is (with some of the landmines removed) and transformed into a peace and nature park - a legacy salvaged from the bitter Cold War battle of a nation divided against itself.
The DMZ provides an interesting example of inadvertent human preservation of natural ecosystems that are rapidly disappearing in otherwise "peaceful" parts of the world (it should be noted however that the DMZ is still too small to support genetically healthy wildlife populations over the long-term).