The Immense, Eternal Footprint Humanity Leaves on Earth: Plastics -- Pay attention, Cambodians!

Scientists have estimated that between 5 million and 13 million metric tons of plastic are put into the ocean each year. Credit Guillermo Cervera

The Immense, Eternal Footprint Humanity Leaves on Earth: Plastics

New York Times | 19 July 2017

If human civilization were to be destroyed and its cities wiped off the map, there would be an easy way for future intelligent life-forms to know when the mid-20th century began: plastic.

From the 1950s to today, 8.3 billion metric tons of plastic have been produced, with around half of it made since 2004. And since plastic does not naturally degrade, the billions of tons sitting in landfills, floating in the oceans or piling up on city streets will provide a marker if later civilizations ever want to classify our era. Perhaps they will call this time on Earth the Plastocene Epoch.

A new study in Science Advances published Wednesday offered the first analysis of all mass-produced plastics ever manufactured: how much has been made, what kind and what happens to the material once it has outlived its use.

Roland Geyer, the lead author of the study, said, “My mantra is that you can’t manage what you don’t measure, and without good numbers, you don’t know if we have a real problem.”

The authors, who come from the University of California, Santa Barbara, the University of Georgia and the Sea Education Association in Woods Hole, Mass., used plastic production data from a variety of sources to make their estimates.

Their findings suggest that staggering amounts of near-eternal litter is present in the environment — the oceans, landfills and freshwater and terrestrial ecosystems — and the numbers are quite likely to increase, with 12 billion metric tons accumulating in landfills or in the environment by 2050. (One metric ton is 1.1 short tons, the measure more commonly used in the United States.)

Scientists estimate that five million to 13 million metric tons of plastic enter the ocean each year, according to previous studies. New data suggests contamination in rivers and streams, as well as on land, is increasingly common, with most of the pollution in the form of microscopic pieces of synthetic fibers, largely from clothing.

The primary explanation for the rocketing rise in plastic is its use in packaging, which accounted for about 42 percent of nonfiber plastic production in 2015. Building and construction is the next largest plastic-consuming sector; it used 19 percent of nonfiber plastic that year.

The authors estimate that packaging, which is typically used for less than a year, made up 54 percent of the nonfiber plastic that was thrown away in 2015.

Most of the plastic that has been made is no longer in use — about 6.3 billion metric tons of plastic have been thrown away since 1950. About 12 percent of that has been incinerated, which is the only way to permanently dispose of plastic; 9 percent has been recycled, which only delays final disposal; and 60 percent — about 4.9 billion metric tons — is in landfills or scattered in the environment.

In Europe, 30 percent of nonfiber plastic is recycled, compared to 9 percent in the United States. Europe also burns more plastic — about 40 percent of its nonfiber plastic waste — while the U.S. incinerates around 16 percent. China recycles about 25 percent and burns about 30 percent of its plastic waste. The authors estimate that recycling, disposal and incineration rates in the rest of the world are probably similar to those in the United States.

Dr. Geyer cautioned that recycling was not a cure-all for global plastic pollution. He said the sole benefit of recycling was to reduce the amount of new plastic being produced, adding, “We don’t understand very well the extent to which recycling reduces primary production.”

The features that have made plastic so important in the global market are the same ones that make it such a pervasive pollutant: durability and resistance to degradation.

Dr. Geyer said there was not enough information on what the long-term consequences of all this plastic and its disposal would be. “It accumulates so quickly now and it doesn’t biodegrade, so it just gets added to what’s already there.”

“Once we start looking, I think we’ll find all sorts of unintended consequences,” he added. “I’d be very surprised to find out that it is a purely aesthetic problem.”