Surviving the Plastocene.

Megatherium – the giant sloth – failed to survive the Pleistocene. Can we do a better job navigating the Plastocene?

The bar might seem low – but the stakes are high, and, fact is, only time will tell.

Some of us can remember a time when one of the arguments for weaning ourselves from fossil fuels was the precious hydrocarbons involved might be more needed and put to better use in the manufacture of plastics.

Today, however, those plastics have joined fossil-fuel use at center stage of the environmental discussion. A quick summary of where this stands:

Oceans. Recent plastics headlines have focused on the oceans. Read some of the media coverage, happen across reference to The Great Pacific Garbage Patch or one of the other major ocean gyres that trap such waste, and see some of the images that have been attached to that coverage, and you might be forgiven for getting the impression that a giant, visible mass of plastic debris is out there in the Pacific, a kind of Bayway-by-the-sea. The reality is less visibly dramatic, but cause nevertheless for concern. NOAA’s National Ocean Service provides this primer material:

While it’s tough to say exactly how much plastic is in the ocean, scientists think about 8 million metric tons of plastic enter the ocean every year. That’s the weight of nearly 90 aircraft carriers[1].

These plastics come in many different forms. Just think about all the plastic items you use daily: the toothbrush you grab first thing in the morning, the container your lunch comes in, or the bottle you drink water from after your workout.

All these things get used and, eventually, thrown out. Many plastic products are single-use items that are designed to be thrown out, like water bottles or take out containers. These are used and discarded quickly. If this waste isn’t properly disposed of or managed, it can end up in the ocean.

Unlike some other kinds of waste, plastic doesn’t decompose. That means plastic can stick around indefinitely, wreaking havoc on marine ecosystems. Some plastics float once they enter the ocean, though not all do. As the plastic is tossed around, much of it breaks into tiny pieces, called microplastics.

The first thing that comes to mind for many people when they think of microplastics are the small beads found in some soaps and other personal care products. But microplastics also include bits of what were once larger items.

Microfibers, shed from synthetic clothing or fishing nets, are another problematic form of microplastic. These fibers, beads, and microplastic fragments can all absorb harmful pollutants like pesticides, dyes, and flame retardants, only to later release them in the ocean.

Airborne plastic. Researchers sampling the Pyrenees in southwestern France, 100 km from any nearby city, captured particles falling in dust, rain, and snow in numbers averaging some 300-400/day/m2, leading them to estimate that if the figure were representative, perhaps 2000 tons of such airborne plastic particulates might blanket France every year.

Plastic in humans. These figures hint that humans may be ingesting quite a bit of plastic; and some evidence is beginning to emerge showing that is so: new estimates put this in the range of some 40,000-50,000 microparticles per person per year. But to date, only a fraction of the foods we eat have been investigated. Scientists point a finger at seafood as a possible pathway; but environmental dust may be a comparable source for many of us. And that’s before we look into the plastic wrap protecting so much of today’s food in stores. So the actual figure might be substantially larger.

How you take your water also makes a difference. Tap water? Add another 4,000 plastic microparticles/year. Bottled water? Add another 90,000.

Thresholds for detectable effects on human health, and the nature of those effects, remain to be investigated.

The plastocene as a thing. Years ago geologists identified a K-T meteor impact some 65MY before present as likely responsible for a massive extinction of the dinosaurs at the Cretaceous-Tertiary boundary. That inference was based in part on discovery of a thin layer rich in iridium (an element common in asteroids, but rare in the Earth’s crust) found worldwide in sedimentary rocks of the period. In a similar way today, geologists have found layers of plastic waste marking flooding events, and have suggested such layers may oneday be evident in sedimentary records of the future. They’ve coined the term Plastocene.

There’s little joy in this (still fragmentary, but developing) picture. It seems unlikely that a touch of microplastics in our diet will be found to be the missing micro-nutrient that will now start to unlock massive, previously unrealized human potential.

Instead, our pervasive and growing dependence on plastics, the rapid emergence of the problem, prior experience with other environmental pollutants – the whole of our human experience – should encourage caution.

The problem is in these respects reminiscent of the CO2 issue.

Which brings us back to our Pleistocene icon, the Megatherium. Weighing in at 9000 pounds and some 20 feet long, it was hardly nimble, but apparently was a rousing ecological success for a few million years, presumably because it didn’t have to fear predation. Ultimately, however, it was done in, possibly hunted to extinction by early humans, during the Pleistocene.

Megatherium probably didn’t see extinction coming.

21st-century humankind, of course, is increasingly a Mega-creature of sorts: mega- in our impacts, even to the point of residing in one or another Megalopolis. When it comes to contemplating our circumstance, we are individually and in aggregate certainly far more aware than Megatherium. However, that situational awareness aside, we have yet to prove that when it comes to corrective action we are any less ponderous, or, for that matter, any less, well – slothful than this critter. (Perhaps we’re paralyzed not by lethargy so much as our disputatious nature, but the end result is the same.)

Cleanup doesn’t seem to be a useful option. We need a multi-media monitoring and study – coordinated development of understanding of plastic and its pathways and fates – from production to use to dispersal and fragmentation – spanning the meteorological, oceanographic, and public-health communities. In parallel, we need a vigorous, soundly based, internationally-coordinated action-oriented plan for reducing plastic use at its source, and capturing plastic materials at the end of their useful lives.

Sound familiar? Yes. Sound particularly tractable? Some think so; in fact, see it as a distraction from the main CO2 challenge. But others are less sanguine, particularly when it comes to developing the needed sense of common purpose.

[1] (footnote added). To size the problem, this is about 3% of global annual production/consumption.

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