Plastic pollution from fibre optic drones may threaten wildlife for years

Introduction 

Russia’s war in Ukraine has been heavily shaped by the use of drones, which in some cases have accounted for up to 80% of casualties during combat missions. Ukraine currently produces four million drones annually and to counter the drone threat, both sides have developed and adopted increasingly effective electronic warfare (EW) systems. In turn, this has driven further innovation: drones controlled by fibre optic cables. This prevents jamming from EW systems, with the drones also flying at low altitudes to avoid manual detection. Single mission fibre optic drones have become a new norm. Russia was the first to adapt this technology for combat and their success saw Ukraine quickly follow. It is suggested that fibre optic drones now comprise around 10% of Ukrainian production.¹ 

The immediate and long-term environmental impacts of the kilometres of cabling remain unclear but several concerns are explored in this post. These include the potential release of microplastics from degraded cables, contamination from hazardous chemicals such as PFAS, risks to wildlife from physical entanglement, and the complications they may pose to activities such as mine action. 

A fine mess

Two types of optical fibres are used in communication: Glass optical fibre (GOF) and polymer optical fibre (POF). Both allow the transmission of data via light but differ in material composition and performance. The core of GOFs is made from high-grade silica glass in a plastic cladding. However, GOF is brittle, heavier and less flexible compared to POF polymer fibres. These make POF more suitable for drone use and more likely to be the focus of Russian and Ukrainian production. The fossil fuel derived polymers used in POF typically include a fluoropolymer cladding — such as PTFE, FEP or PFA — and a polymethyl methacrylate (PMMA) core.  

The spools of optical fibre carried by drones typically contain between five and 20 km of cable, though there have been reports of drones transporting spools as long as 41 km. Typically, multiple drones operate in the same area, this can result in large quantities of cable being draped across frontline areas. In the context of ongoing combat, these cables are rarely recovered and are often damaged by explosions or fires. Even where they may be recovered in future, their mixed compositions make them difficult to recycle.

Threats to wildlife and habitats

POF fibre optic cables are lightweight and extremely strong and so discarded cable may pose a serious entanglement risk for wildlife, particularly birds, bats and ground dwelling mammals. Even where wildlife avoids entanglement the cables can act as barriers to movement, effectively becoming fences in the sky, on the ground and in waterways. As such they represent a major threat to wildlife by reducing access to high-quality habitat or important resources, and in so doing reducing ecosystem functioning. 

Due to their composition, these cables could persist in the environment for more than 600 years, posing a substantial long-term threat. To date examples of wildlife impacted by fibre optic cable during wartime have been hard to find but there may well be similarities to “ghost gear”. Like ghost fishing gear, fibre optic cable could become wrapped around the necks of animals causing amputation, asphyxiation or starvation. 

Charlie Russell, a researcher at the UK’s University of East Anglia who has studied the impact of the war on migratory birds said: “Wildlife in Ukraine faces a wide range of impacts from the ongoing conflict, many of which will last long into the future. Fibre optic cables from drones cover large areas or wooded and edge habitats, forming dangerous webs across trees and clearings that will pose a significant risk of entanglement and death to many species, including threatened birds and bats, for years to come.” 

He continued: “The materials used make them difficult to identify and unlikely to naturally degrade, and they already cover vast swathes of important habitats. Removing them will be difficult but integral to long-term conservation efforts post-conflict.”

Microplastics, chemical residues and health hazards

Beyond the physical risks posed by fibre optic cables there are also environmental concerns relating to their degradation. In conflict zones, cables are often deployed in areas exposed to blasts and fires, which can damage or degrade them. This short-term degradation can break down cable materials, releasing micro plastics or, if burnt, harmful gases. Over time, exposure to UV radiation, abrasion, and temperature fluctuations can further degrade the cladding and core, generating plastic pollution. 

The core material of POF cables — PMMA — is versatile, widely used in a range of applications and is suggested to be generally stable and resilient under “ambient conditions”; researchers’ views vary however. However, like most polymers it degrades over time and can break down into nanoplastics, with research linking PMMA nanoplastics in water to risks to aquatic species. In conflict zones, this degradation is likely to occur more rapidly. Research suggests that micro- and nano-sized PMMA particles can inhibit the growth of certain marine diatoms and agricultural crops. When burned, PMMA can release harmful gases such as carbon monoxide and nitric oxide. 

The fluoropolymer cladding and outer layers of cables are also of concern. Fluoropolymers fall within the class of highly persistent per- and polyfluoroalkyl substances (PFAS), which do not readily degrade in the environment and can contaminate soil and water. The environmental and health impacts of PFAS are becoming increasingly well understood, and alongside munitions and firefighting foams, this fibre constitutes yet another military PFAS source.

A barrier to emergency, assessment and remedial activities

Residual drone cabling not only poses a risk of entanglement to wildlife, it also presents a risk to vehicles and images of entangled vehicle tyres and axles can be already found on social media. Because the affected frontline areas cover a wide range of habitats and land use types, this suggests that a range of industries and practices may be impacted. These include a wide range of agricultural machinery, vehicles used by protected area staff, as well as forestry vehicles — including the firefighting vehicles frequently called upon to tackle landscape fires.    

Critically, abandoned cabling may also create a challenge for mine clearance operations, particularly for mechanical demining equipment such as mine flails. As this is a novel phenomenon, the impact of cabling on clearance operations is currently unclear but it seems inevitable that it will add to what are already complex remedial operations. 

A new form of conflict pollution?

Fibre optic drone cables appear to represent a new and important environmental threat in conflict zones. Ukraine is one of a number of conflicts being closely watched by other states for developments in tactics and equipment, for example, China has been testing this new and relatively inexpensive EW-resistant drone technology.  

It is currently unclear whether the technology will end up being viewed as just a stop-gap, or whether the low cost and ease of manufacture will see the drones become more widely used in both combat and training. For example, Ukraine is experimenting with “machine vision” — the ability to lock on to and track a target once identified by an operator, even after contact is lost with them due to EW interference. However, what is clearer is that the physical hazards and pollution risks associated with their use mean that it is a trend that needs to be monitored.

 

Leon Moreland is a Researcher with CEOBS, Linsey Cottrell, Eoghan Darbyshire and Doug Weir contributed to this post. Our thanks to Charlie Russel at the University of East Anglia, and to ‪@danielr33187703.bsky.social‬ for initially highlighting the rise of fibre optic cables.