Changing of the guard – plastics and the end of the Holocene

Geological era – a scientific term denoting a period in the Earth’s history mostly delimited by the appearance or extinction of particular organisms. Now, according to an international body of geologists (Working Group on the ‘Anthropocene’), a new geological era is beginning. The preceding one, the Holocene, lasting about 12,000 years, has thus been superseded by the Anthropocene (Greek: anthropos, human).

The changes that humans have caused on our planet have meanwhile become so drastic that they may truly justify the naming of a new geological era. However, the dating of its inception is still being discussed. Besides phenomena like species extinction, species migration and climate change, the composition of sediments has also altered. The newly forming sediments have since the middle of the last century contained industrial fly ash, elementary aluminium and also numerous plastic particles (“Key materials of the new era”) [1]. The use of “plastics” began in the Stone Age, with carbonised birch resin as an adhesive and sealant, while today we are seeing carbon-based lightweight construction and mass plastics for packaging.

We humans seem to love plastics – but why exactly?

Plastics are affordable, and possess a multiplicity of valuable technical properties. These in their turn render them a superior choice of material for very many applications. So far, so good.

But if they escape from the technical cycle of use and recovery or due and proper landfilling, they can be harmful to the natural environment. Familiar examples include the Great Pacific Garbage Patch (plastic particles floating in the ocean), the accumulation of pollutants involving hydrophobic plastic particles (usually polyolefins) and direct damage to living creatures, which confuse plastic with food, or are caught in sizable plastic parts like lost nets or lines.

One reason for these problems, of course, is the sometimes over-careless way in which these long-lived substances are handled. Not enough of them are being recovered as yet, and too many of them end up (either intentionally or unintentionally) in our natural environment (lost and littered).

Another cause, however, lies in what is at first glance a very valuable property of the material: its longevity. Many plastics are what is called “persistent” (i.e. very long-lived) under normal environmental conditions. There are, of course, natural substances that endure for a long time (particularly mineral substances, as can be deduced from fossils), and under certain circumstances like permafrost or oxygen exclusion in swampy soils, almost everything will last for a long time. However, a material category like modern-day plastics is unprecedented in nature.

Besides its longevity, another major factor is the large mass of plastics produced, totalling approximately 280 million tons a year worldwide – about as much as the seven billion humans living on our planet. Moreover, plastic has a density similar to that of water, which means that even relatively large plastic particles will float in water. This is why, when they arrive in bodies of surface water, materials remain for a long time in the inhabited sections of the natural environment, instead of quickly sedimenting.

What does that mean for us as users of plastics? What should we be doing? Should we do without plastics entirely?

I don’t think this is the right approach. That would be merely a variant of the “head-in-the-sand response”. Plastics are meanwhile an indispensable part of our world, and whether possible product alternatives without plastics perform better in life-cycle assessments is something that needs to be carefully scrutinised in each particular case. Renunciation verging on self-mortification is in a global context surely neither desirable nor acceptable to a majority.

Meanwhile, almost everyone has realised that we have to find sustainable solutions in all areas if we humans wish to survive as a species in the longer term. Meaning solutions that are viable for our planetary habitat even in a lengthy time-frame. There is no alternative in the long run to properly functioning closed cycles, whether they’re technical or natural and bio-based. One of the current visionaries pondering these causal interactions is Michael Braungart, with his call for “cradle-to-cradledesign.

So as far as the plastic waste in our natural environment is concerned I believe a twin-track strategy is appropriate for solving these problems.

Firstly, of course, the above-mentioned “lost and littered” quantities have to be reduced in future. Less material must be lost and deliberately thrown away in the natural environment. Properly functioning technical closed cycles are the key here: genuine plastics recycling with a high collection rate.

Secondly, however, we need to consider and discuss what material properties are actually required for which product. The diversity in the class of plastics is almost as great as in the class of natural substances, and more are continually being added. Technical properties, re-usability and longevity have to be appropriate to the application concerned, and perhaps it’s not necessary to manufacture every mass product from a material that needs 30 generations before it is broken down in the natural environment.

I am firmly convinced that plastics are a part of the solution and not just a part of the problem when it comes to guiding our new “Anthropocene” geological era into a stable, life-friendly phase.

 

(1, Interview in Spiegel 39/2016 with the geologist Reinhold Leinfelder)