Plastic waste accelerates climate change and species decline – knowledge


Several international scientists have issued an urgent warning in the current trade magazine Science from the consequences of plastic litter. Annika Jahnke, environmental chemist at the Helmholtz Center for Environmental Research (UFZ) in Leipzig, is one of them. In an interview with the SZ, she describes ways out of the plastic crisis.

SZ: In your contribution to Science– You and other scientists write that the amount of plastic waste is increasing dramatically. In many countries, at least it feels like a lot is being done to avoid exactly that. In Germany, for example, there are far fewer plastic bags, plastic straws are taboo, and many people collect their plastic waste so that it can be recycled. Doesn’t all of this bring anything?

Annika Jahnke: Yes, of course these measures bring something. But there is still far too much plastic that does not end up in the waste system and then end up in rivers and seas, for example. And there are still far too many products that contain plastic or are unnecessarily wrapped in plastic.

Do you know how much plastic gets into the environment every year?

There are models that can estimate that. In our review article, we cite figures from various studies that are also published in Science have been published. According to this, between nine and 23 million tons ended up in the aquatic environment in 2016. In addition, terrestrial ecosystems were again polluted with approximately the same amount. On the basis of such figures, you can then calculate various scenarios for the future. It emerged that even with drastic and globally concerted measures to avoid plastic waste, an increase in emissions can still be expected.

What would such a drastic measure be?

For example, plastic waste should no longer be exported to regions where recycling technologies are less advanced than ours. Unfortunately, this is still being done and is very problematic. In addition, when avoiding plastic, it would be important not only to start at the end and, for example, to collect plastic that is already in the environment, but also at the beginning. So that not so much plastic is created. One way to steer this politically would be to make sure that recycled plastic is cheaper than new plastic. During the Corona crisis it was at times that new plastic was five times cheaper than recycled plastic because the price of crude oil has fallen so sharply. Of course, this is not an incentive at all to focus more on recycling.

Do the face masks that everyone is now wearing to protect themselves against the coronavirus actually exacerbate the plastic problem? You can now see them lying around carelessly discarded.

That is a question that is being explored. Of course the masks contain plastic, but it is currently unclear how relevant this is.

What are the main sources of plastic?

Huge amounts are used in the packaging industry around the world. The construction sector is also an important factor, as is textiles: many items of clothing contain plastic, which then gradually gets into the environment, for example when washing. The wastewater first enters the sewage treatment plant. Most of the particles are removed there, but not all.

The environmental chemist Annika Jahnke is deputy head of the ecological chemistry department at the Helmholtz Center for Environmental Research (UFZ) in Leipzig. As a professor at RWTH Aachen University, she deals with the chemical pollution that organisms are exposed to over their entire lifespan.

(Photo: Sebastian Wiedling / UFZ; Sebastian Wiedling / UFZ / Sebastian Wiedling)

Is there actually still a place in the world that is plastic-free?

You really have to look. It is a huge problem that the material ends up in areas from which it can no longer be removed. For example, because these regions are difficult to access: the deep sea, for example. An alarming amount of plastic even ends up in arctic regions.

Where on earth does most of the plastic accumulate?

There are five garbage vortices in the oceans where the material accumulates: in the North and South Pacific; in the North and South Atlantic and the Indian Ocean. The fact that the plastic accumulates there is due to the global ocean currents and the prevailing wind directions. On land, soils used for agriculture are sometimes heavily polluted because the material is contained in fertilizers or sewage sludge. In some regions, farmers also use giant plastic sheeting to cover the crops.

Why does plastic actually harm the environment?

In recent years, research has focused primarily on ecotoxicological studies. Experiments were carried out in the laboratory that had little to do with the conditions in the environment. In these studies it was found that only extremely high concentrations of plastic cause damage that does not occur in the environment. The conclusion was that plastic is not a problem.

You and the other writers in Science but see it differently …

Exactly! We think that it is not just about the ecotoxicological effects, but that many other aspects play a major role.

Which?

Marine mammals, turtles and sea birds eat the plastic and perish because they cannot excrete it again. In addition, many animals, including endangered species, get caught in plastic fishing nets and die. This can contribute to the loss of biodiversity. But we also suspect that plastic waste can exacerbate climate change because it disrupts the global carbon cycle.

In what way?

Among other things, the plastic particles in the sea cloud the water and thus shield the phytoplankton and blue-green algae from sunlight. This means that these organisms are restricted in their growth and bind less carbon dioxide from the atmosphere.

Is there a realistic chance of removing all of the plastic waste from the environment?

In short: no. There are many regions in the world that are simply not accessible for cleaning. Not even if the plastic parts are large. And the smaller the particles, the more difficult it is to remove them from the environment. The problem is compounded by the fact that plastic degrades naturally extremely slowly. A fishing net, for example, has an estimated retention time of several centuries. This is why it is so important that significantly less plastic ends up in the environment and more is recycled.

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