Do you worry about the nuclear waste and bombs squirreled away in underground bunkers? And wonder what would happen if there weren’t humans constantly monitoring these stockpiles? Such questions once led me to read Alan Weisman’s The World Without Us, which explores what would happen to the planet if humans suddenly disappeared. His book answers the question: How long would it take Earth to recover from us?
I was relieved to learn that, at least with regards to uranium bombs, the speeds required for the fissionable material to collide and explode are not found in nature. Short of pushing a uranium bomb off the side of the Grand Canyon, it isn’t likely these weapons will go off accidentally. Learning this eased my fear of a group of renegades (or poorly trained government employees) mishandling nuclear bombs in transit and accidentally dropping one. Furthermore, if one day we return to a planet of apes, stone banging and jumping on nuclear bombs won’t deploy them either.
However, the bombs’ casings, like the power plants and nuclear waste containers, eventually will corrode. At that point, all surrounding life will be exposed to cancer-causing and mutation-forming alpha particles that will take at least 250,000 years to join background levels of radiation, and hence become nonlethal to life (as we now know it).
With regards to Weisman’s question — how long will it take the planet to recover from our environmental impact — some toxic substances will take hundreds of thousands of years to dissipate, while other contaminants might flush from Earth’s system in a mere year without humans around.
For example, despite being on the planet little more than fifty years, plastic — like nuclear waste — may be one of the longest reminders of late modern civilization. Plastic poses a formidable threat, especially to sea life. When they aren’t hopelessly snared in six-pack rings and nylon cord, many sea animals are mistakenly eating plastic pellets that have the colorful markings of food but could prove deadly once ingested. Furthermore, at present there is no way to naturally breakdown plastic. Even so-called biodegradable forms require environmental conditions few plastics ever experience — intense sunlight and enough heat for them to photodegrade — since most end up swirling in cool ocean currents or on the ocean floor.