Interesting, but useless, thought experiment: what would the earth be like without humans.

"The sad truth is, once the humans get out of the picture, the outlook starts to get a lot better," says John Orrock.

Of course it looks better -- because environmentalists define "better" as "no humans."

Would the footprint of humanity ever fade away completely? ... Lack of maintenance [would] spell an early demise for buildings, roads, bridges and other structures. Though modern buildings are typically engineered to last 60 years, bridges 120 years and dams 250, these lifespans assume someone will keep them clean, fix minor leaks and correct problems with foundations. Without people to do these seemingly minor chores, things go downhill quickly.

Yeah, but without people using them, they don't go downhill all that quickly.

The best illustration of this is the city of Pripyat near Chernobyl in Ukraine, which was abandoned after the nuclear disaster 20 years ago and remains deserted. "From a distance, you would still believe that Pripyat is a living city, but the buildings are slowly decaying," ... "The most pervasive thing you see are plants whose root systems ... and are rapidly breaking up the structure. You wouldn't think ... that we have a big impact on keeping that from happening, but clearly we do."

Which just goes to show you how an environmentalist defines "better."

The lack of maintenance [would] have especially dramatic effects at the 430 or so nuclear power plants now operating worldwide. ... As cooling water evaporates or leaks away, reactor cores [would] likely ... catch fire or melt down, releasing large amounts of radiation. The effects of such releases, however, may be less dire than most people suppose.

But the money quote:

The area around Chernobyl has revealed just how fast nature can bounce back. "I really expected to see a nuclear desert there," says Chesser. "I was quite surprised.

Have environmentalists recalculated the "damage" humans do to the environment, given that their previous estimates of Chernobyl were wildly off? Or have they just added "acceleration factors"?