"The World Without Us"

But it is his science reporting, at once lucid and full of wonder, that is the heart and soul of this book. Even when he is reporting on the grimmest, most dispiriting phenomena -- for me, it was the inconceivable amount of microscopic plastic bits that we are dumping into the oceans -- Weisman evinces a spirit of joy in scientific inquiry for its own sake. It's that playful objectivity, which feels Buddhistic rather than detached, that makes "The World Without Us" so original and refreshing.

That, and the scientific popcorn. Did you know that the entire population of the world could fit into the Grand Canyon? Or that the fertilizer-choked dead zone at the mouth of the Mississippi is larger than New Jersey? Or that much of the world's garbage landfill is made up of newspapers? Or that Norway is storing samples of the world's crop seed varieties on an Arctic island in case of a global catastrophe? Or that the reason tires don't degrade is that they're one enormous molecule? Or that north of the 60th parallel, Canada has more lakes than the rest of the world combined? Such tasty morsels are sprinkled on virtually every page of this book.

The most obvious question, of course, is: What would happen to our homes? Weisman walks us meticulously through the steps that lead inevitably to the complete destruction of almost every single part of our houses. The first and last enemy is water. Water sneaks in at the weak points of roofs, near the chimney, for example. It enters around the edges of nails. Mold begins to grow on wet wood; under the mold, "threadlike filaments called hyphae are secreting enzymes that break cellulose and lignin down into fungi food." The roof falls in. More water enters through the windows, some shattered when birds flew into them. The floor corrodes. Squirrels and lizards eat the drywall. Vinyl siding begins to crack as its plasticizers weaken. Even aluminum begins to break down, as salt eats it away. Steel gas pipes begin to rust away. PVC pipe yellows and thins. In 500 years, just about everything is gone, eaten away by the elements, the remaining scraps covered up by vegetation.

A few things remain longer. Bathroom tile, because "the chemical properties of its fired ceramic [is] not unlike that of fossils." Stainless steel pots, pans and knives, especially if they're buried out of the reach of destructive oxygen. Perhaps aluminum, although we'll never know -- the rate at which this new metal degrades is not yet known. Thick cast iron endures, as we know from Roman ruins, so fire hydrants may last for millennia.

Yet forces that mankind has set in motion may preserve things that would otherwise disappear. If oceans rise as a result of global warming, wood-framed houses "may be preserved like the timbers of Spanish galleons wherever rising seas pickle them in salt water."

As with houses, so with cities. Weisman describes how millions of gallons of water under New York City, unchecked by pumps, would flood the subways. "Within 20 years, the water-soaked steel columns that support the street above the East Side's 4,5 and 6 trains corrode and buckle. As Lexington Avenue caves in, it becomes a river." Meanwhile, pavements would be breaking apart as ice expands in cracks. Weeds and potent invaders like ailanthus, with no city maintenance crews to stop them, would wreak havoc. Lightning fires would start, and gas mains ignite. As skyscrapers' windows break, water would corrode even concrete floors. Subbasements would weaken. High winds from hurricanes, more powerful in the future, would topple giant buildings. Bridges, their unpainted joints cracking as they expand, would collapse. The strongest, like arch railroad bridges, could last 1,000 years, although earthquakes could bring them down. Even the gigantic garbage fills on Staten Island would finally disappear, when the next Glacier Age returned.

The plant and animal world would change dramatically as well. Colonizing trees would take over, and biodiversity increase. Many imported plant species would wither and die, or revert to more primitive ancestral forms. Some natives would lose out in the struggle as well. Coyotes, bears and wolves would return. Frogs would breed in Manhattan's rivers.

Weisman ends up wandering -- literally -- all over the map, alternating between future and past, chemistry and politics, the fate of imported apple trees and the outer reaches of the universe. This kaleidoscopic approach can at times feel scattershot, but his subject is so vast and multifaceted that the only way to do justice to it is to jump around. His digressions allow him to deal with the philosophical and foundational questions raised by his thought experiment. For his concern isn't just to figure out what the world would look like without us. It's also to put that question in context by assessing what we have done to the world, for better and worse. And what the world would have looked like if we never existed.

Having whetted our appetite with this vision of a dissolved New York, Weisman then characteristically pulls far back, to a geological perspective -- the only one that can make sense of "one of the human-crafted artifacts that will last the longest after we're gone ... our redesigned atmosphere." For more than a billion years, great sheets of ice have intermittently covered the Earth. The last glacier left New York only 11,000 years ago -- which would make us due for another Ice Age now, were it not for the fact that we've stuffed "our atmospheric quilt with extra insulation": CO2. As a result of human activity, "there's more CO2 floating around today than at any time in the past 650,000 years." This means that glaciers won't encroach for at least another 15,000 years.

What will the effects of this vast climate change be? Weisman notes that scientists posit three different scenarios. In the first, the world gets warmer. In the second, the cold water from melting ice caps stops the Gulf Stream, and precipitates another Ice Age. In the third, the two extremes balance each other and leave things more or less the same. But no matter what scenario transpires, Weisman notes, if we continue to pump carbon dioxide into the atmosphere, the great northern and southern ice caps will keep melting. And depending on how much they melt, many cities -- including New York --- could be covered by water.

Next page: In the future, will organisms eat plastic?