The World Without Us.

The World Without Us by Alan Weisman (Thomas Dunne Books, 2007) 304 pp.; $24.95

AFTER 1600 YEARS of astounding cultural achievement, millions of lowland Maya vanished from their Meso-American paradise during the eighth century. Some have blamed epidemics, drought, or environmental ruin for this mysterious disaster. Vanderbilt University's Arthur Demarest, however, attributes the Mayan catastrophe to something much more insidious and familiar: greed. For centuries the Maya had settled inter-societal disputes through grisly yet limited violence. But, to satisfy an increasingly gluttonous and parasitic nobility, swelling throngs of laborer-soldiers were forced to erect new temples and fortresses and to attack and conquer neighboring city-states. Cooperative trade was undermined and population began to concentrate in the treacherous rain forest. Mayan peasants had no choice but to overwork diminishing farmlands ever nearer to the safety of city walls.

Undoubtedly, there are many means by which civilizations might unwittingly annihilate themselves. But the Mayan exemplar reveals how imprudent priorities, short-term thinking, and a glaring but still common misapprehension of the tenuous relationship between societies and ecologies can result in a brisk demise for even the most advanced and powerful culture--perhaps for the entire human species. So what might the world look like without us? asks reporter and associate professor of journalism, Alan Weisman, in his forebodingly titled new book, The World Without Us. How might remaining life evolve in response to both our absence and our varied legacies?

Toward the close of the Pleistocene epoch, some 13,000 years ago, tens of millions of American megafauna, including camels, mastodons, and six-ton ground sloths abruptly disappeared within a millennium--a mere micro-flash of geologic time. Some think retreating glaciers and rising Holocene temperatures caused their extinction. Others have blamed a sudden and short-lived Ice Age. Paleoecologist Paul Martin, whose work Weisman details, disagrees, pointing out that large, mobile animals are relatively well protected from extreme temperatures, and that ancient fauna--obviously immobile--seem to have fared quite successfully. Most significant for Martin, however, are the facts that ground sloths survived 5,000 years longer in Cuba, Haiti, and Puerto Rico, and that the woolly mammoths of Wrangel Island endured 7,000 years longer than their southern cousins. That such dates also correspond to evidence of the first human settlements in these remote areas suggests that, yet again, lack of self control and foresight may have sealed the unfortunate fate of not just a single, isolated culture, but of complete species numbering in the dozens.

Martin's progressively popular "Blitzkrieg" theory posits that humans, the Clovis culture of present-day New Mexico in particular, caused the extermination of seventy-five percent of America's late Pleistocene megafauna--plodding giants that, relative to their African and Asian counterparts, were afforded precious little time to adapt to large-brained Homo sapiens who, by 13,000 years ago, had ably hunted with fluted stone points fastened to wooden shafts and portable spear levers called atlatl. Even so, intelligence and technology served the new Americans for only so long. After their game disappeared, so did the Clovis people. But if Martin is right and if humanity continues to ignore its historical lessons, perhaps extinct megafauna, in one form or another, will return.

But return to what? Apparently, to an ocean brimming with synthetic, petroleum-based polymers--elastic, invisible, and impossibly resilient hydrocarbon molecule chains that we consumers commonly refer to as "plastics" Although the world's navies and commercial vessels dump some 639,000 plastic containers per day, according to Captain Charles Moore of the Algita Marine Research Foundation, 80 percent of middle-ocean flotsam originates on land. India claims 5,000 plastic bag-processing plants and Kenya manufactures 4,000 tons of the non-recyclable sacks every month.

All of which pales both quantitatively and qualitatively in comparison to the 5.5 quadrillion plastic pellets, or nurdles (250 billion pounds worth), that we manufacture annually. The problem with nurdles specifically is at least two-fold. First, these plastic crumbs have always attracted and absorbed deadly and durable poisons like DDT and PCBs, the latter of which have proven to inflict hormonal chaos upon newly hermaphroditic fish and polar bears. Second, numerous and sundry creatures, if by design or mistake, have ingested and will continue to ingest nurdles in copious and, evidently, life-altering amounts.

The tragedy of plastic more generally, whether in the form of pellets, bags, or nylon nets, is the composition's stubborn longevity. When unsubmerged, at least, plastics are photodegradable, or vulnerable to ultraviolet radiation. Unfortunately, they won't biodegrade in step with any practical time scale. So, because humanity can do little except curb its production of plastics, nature will have to rely on its own strategies. Microbes have already evolved to consume natural hydrocarbons, including oil. But, alas, plastics have existed for no more than fifty years. Research scientist Anthony Andrady remains dryly hopeful, however. Don't worry, he quips, evolution should have plastics well under control within another 100,000 years or so.

Nuclear waste tends to be far less accommodating. Without us, intact nuclear warheads--some 30,000 of them--would probably not explode. But their bomb housings would surely corrode and disintegrate within a few thousand years, exposing ten to twenty pounds of weapons-grade plutonium, with a half-life of 24,110 years, per ICBM. Relatively heavy, released alpha particles won't penetrate the skin. Once inhaled, though, even one millionth of a gram can cause lung cancer. On the brighter side, less than a pound will remain after 125,000 years, and, after 250,000 years, bombs shouldn't be an issue at all.

But uranium waste is another matter entirely. During the enrichment process, uranium-235, with a half-life of 704 million years, is separated in a centrifuge from "depleted" uranium-238, with a half-life of 4.5 billion years. When alloyed with steel, 500,000 tons of the depleted variety in the U.S. alone becomes useful for the cheap production of armor-piercing projectiles. Of course, U-238 bullets are still hot--l,000 times more radioactive than the background level--and they will likely remain contaminated beyond terrestrial time.

Far hotter waste, 13,000 tons worldwide and 3,000 tons in the U.S. alone, is produced annually in the world's 441 active nuclear plants. Except for defense rubbish, which is currently stored at the Waste Isolation Pilot Plant in southeastern New Mexico, all nuclear waste in the United States is contained only temporarily. Our most prolific plant, the triple-reactor, 3.8-billion-watt Palo Verde Nuclear Generating Station near Phoenix, uses 170,000 fourteen-foot zirconium-alloy rods containing uranium pellets, each of which commands as much energy as an entire ton of coal. Annually, the facility consumes thirty tons of fuel, after which the rods are provisionally submerged into a holding pond approximately forty-five feet deep. When pool space is exhausted, the fuel is removed to steel and concrete "dry casks" Surprisingly, spent fuel grows up to a million times hotter than when it was fresh, as it continues to exchange neutrons and expel alpha and beta particles, gamma rays, and heat.

In our absence, no doubt, the storage pools would quickly boil and evaporate away. And, though certainly more durable, cement and steel casks can persist for only so long. Every fuel rod, it seems, would eventually ignite and erupt into a toxic inferno.

Perhaps most other life would in fact benefit from our absence. So be it. But the salient issue, of course, is not the planet's status without us, as the author's title suggests. Instead, Weisman implicitly offers humanity a rather thinly veiled opportunity to venture beyond the boundaries of its temporal context. With that much accomplished, the author leaves the rest to his readers, and some will leave it at that. But the sober, less passionate truths about ourselves always remain concealed until we dare to glance over our collective shoulder. The truly critical questions are timeless. How long can we go on like this? To what extent are we responsible for the welfare of ensuing generations? Well written and scrupulously researched, The World Without Us explores an impressive range of key social and environmental issues, reporting faithfully without preaching.

Kenneth W. Krause is a former prosecutor and criminal defense attorney with degrees in law, history, literature, and fine art. Books editor for Secular Nation, Kenneth has recently contributed to Free Inquiry, Skeptical Inquirer, The Humanist, Truth Seeker, and Skeptic. He may be contacted at [e-mail].