A warship patrolling the open ocean suddenly detects an approaching threat on its early-warning radar—far beyond the system’s normal operating range, where the target should be virtually invisible.
Yet under slightly different climatic conditions, that same warship, equipped with the same sophisticated radar, can suddenly find itself dangerously blind to an incoming threat well within its normal detection range.
The difference in the warship’s early-warning capabilities comes down to invisible layers of air above the ocean’s surface that can bend and trap electromagnetic signals. Under certain conditions, those atmospheric layers can carry radar signals far beyond their normal range. Under others, they can create dangerous blind spots, leaving approaching threats undetected.
Scientists have found evidence that global warming is making such atmospheric conditions more common and more intense across much of the world’s oceans, potentially dramatically changing how military radar, maritime communications, and navigation systems operate.
The findings, published in Nature Climate Change, are based on an analysis of 86 years of atmospheric data. Researchers identified a persistent increase in the frequency, strength, and height of atmospheric structures known as atmospheric ducts, particularly over tropical and midlatitude oceans.
Ultimately, the evidence shows that evolving climatic conditions will bring another variable into naval surveillance and electronic warfare, where detecting an incoming missile seconds earlier, or failing to detect it at all, can have enormous fatal consequences.
“These thermodynamic shifts alter vertical refractivity gradients and can modulate atmospheric ducts, which are natural waveguides crucial for beyond-line-of-sight electromagnetic propagation,” researchers write. “Ultimately, continuous warming is shifting the marine atmospheric background state towards a highly stratified regime favoring more frequent and intense ducting, with implications for global maritime communication, radar and navigation systems.”
The Invisible Atmospheric Layers That Can Bend Radar Signals
Radar normally operates within the limits imposed by Earth’s curvature. Because electromagnetic waves generally travel along relatively straight paths, conventional radar cannot dependably detect objects far past the horizon.
However, atmospheric ducts can change that.
These structures form when temperature and humidity differences create unusual vertical changes in the atmosphere’s refractive properties. Under certain conditions, electromagnetic waves become trapped within these layers, allowing them to travel much farther than expected.
However, the same phenomenon could also create areas where radar coverage becomes unreliable.
Rather than simply extending detection range, atmospheric ducting can produce misleading returns, unexpected interference, or regions where targets become difficult to detect.
Researchers have long recognized the military importance of these conditions.
The new study even references Ukraine’s April 2022 sinking of Russia’s cruiser Moskva, noting that previous analyses have suggested atmospheric ducting may have played a role in the circumstances surrounding the attack.
The researchers caution that the full tactical picture remains complicated. Their study does not establish that atmospheric ducting caused the ship’s loss. Nevertheless, the example illustrates why perceiving these invisible atmospheric structures matters for modern naval operations.
An 86-Year Record Reveals a Changing Ocean Atmosphere.
To investigate whether atmospheric ducting has changed over time, researchers at several Chinese universities examined climatic conditions between 1940 and 2025 using ERA5, a global dataset that combines historical observations with weather models.
Their study uncovered a broad increase in atmospheric ducting across oceans between approximately 60 degrees north and 60 degrees south latitude.
The changes were especially apparent after the 1970s, when global warming accelerated.
According to the study, the dominant warming-related pattern was associated with an approximately 3-percentage-point increase in the probability of atmospheric duct occurrence and a nearly 200-foot increase in duct height.
The researchers also identified an overall strengthening of ducts across tropical and midlatitude oceans.
The mechanism includes changes in climatic stability.
As ocean temperatures rise, the atmosphere retains more moisture, while warming at different altitudes alters how readily air mixes vertically.
These changes can produce more stable atmospheric layers, encouraging temperature inversions and sharp humidity gradients that trap electromagnetic signals.
Importantly, the effects are not uniform.
While ducting generally increased over warmer ocean regions, the researchers identified declining trends around Antarctica and parts of the high-latitude Southern Ocean.
Natural climate variations, including El Niño and La Niña, likewise influence duct formation. However, the researchers found that these shorter-term fluctuations could not adequately explain the persistent long-term trend.
A New Challenge for Maritime Defense
For naval forces, the findings raise a practical question: Could radar systems designed around historical climatic conditions become less reliable as the climate changes?
The answer depends on location, weather conditions, radar frequency, and the specific atmospheric structure involved.
Stronger ducting does not automatically mean better radar performance. A signal that travels farther in one direction may leave an unexpected coverage gap elsewhere.
This could be significant for warships, coastal surveillance networks, and other systems that depend on reliably predicting electromagnetic propagation.
That said, the research also has limitations. The atmospheric dataset cannot completely resolve evaporation ducts and extremely low-altitude structures, which are particularly relevant to maritime radar. The researchers did not directly measure changes in the performance of individual military systems.
Nevertheless, the findings show that climatic conditions affecting radar and communications are not necessarily stationary features of the operating environment. They are changing alongside the climate.
Ultimately, for naval planners, that means an increasingly important part of the electronic battlespace may be shifting even when the ships, sensors, and weapons themselves remain unchanged.
Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan. Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com