SUSTAINABLE SUBSEA EXPLORING ALIGNMENT OF RESILIENCE AND SUSTAINABILITY IN SUBSEA TELECOMS NETWORKS by Derek Cassidy, Nick Morris & Andrew Parsons Subsea cables are often described as the hidden infrastructure of the digital economy. The global digital economy rests upon a surprisingly physical foundation: a vast, intricate network of fibre-optic cables criss-crossing the ocean floor [1]. These subsea cables are the foundational infrastructure of the modern digital economy, carrying an estimated 99% of intercontinental data traffic[2] and facilitating everything from high-frequency financial trading to essential cloud services. However, as global dependence on this infrastructure grows, so too does the complexity of the challenges it faces. The dual imperatives of resilience (the ability to withstand and recover from physical or cyber disruptions) and environmental sustainability have emerged as the defining pillars of future subsea development [3]. Historically, the subsea cable industry focused primarily on connectivity and capacity. Yet, an escalating landscape of threats, ranging from climate-induced geological shifts and accidental maritime interference to intentional sabotage, has underscored the vulnerability of these increasingly critical systems [4]. Simultaneously, the industry is under increasing pressure to align with global “Blue Economy” goals. While subsea cables are often cited as a lower-carbon alternative to satellite transmission, their lifecycle (from manufacturing and specialised vessel deployment to decommissioning) presents a distinct environmental footprint that must be managed within sensitive marine ecosystems [5]. These pressures also connect to the wider critical-national-infrastructure and security agenda, a link this paper notes without developing into a policy prescription. For years, resilience and sustainability were treated as parallel conversations. Resilience lived with engineers and operators; sustainability sat somewhere between corporate reporting and regulatory engagement. That separation is breaking down. Why? Because unplanned intervention is a double penalty. A fault that forces an urgent repair doesn’t 20
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just risk downtime. It also triggers some of the most resource-intensive activity in the ecosystem: vessel mobilisation, port calls, specialised crews, spares movement, onshore works, and the operational overhead of restoring service under pressure [6]. When repairs are slow—because vessels are scarce, weather windows are tight or permits take time—the system runs “hotter” for longer, often leaning on less efficient operating modes and backup power [7]. At the same time, sustainability constraints are becoming operational constraints. Power availability and quality, local water stress, flood risk, and permitting friction increasingly shape where landing infrastructure can be built and how it can be operated. In other words, sustainability is not just a reporting line item; it can become a real-world limiter of resilience. Increasingly these constraints are also codified in regulation, for example the EU Corporate Sustainability Reporting Directive (CSRD) on disclosure, and the EU Critical Entities Resilience Directive and NIS2 on critical-entity resilience and cyber risk [8]. That observation is accurate, but incomplete. What matters in practice is the whole subsea ecosystem: the cable itself, the landing and interconnection environment, the data centres and backhaul that carry the traffic, and the operational machinery—ships, spares, ports, permits, and people—that keeps everything running when something goes wrong [9]. And things do go wrong. Most faults are accidental, not mysterious: anchors, fishing activity, shoreline dynamics, seabed movement, and plain bad luck [10]. The resilience question is familiar: how can operators keep service running when a fault occurs? Increasingly, there is a second question that cannot be separated from the first: how can that be done without turning every incident into a high-carbon, high-impact emergency response [11]? This paper explores the intersection of these two critical domains. It examines how innovative engineering and diversified routing can bolster cable resilience against a backdrop of increasing geopolitical and environmental volatility. Furthermore, it