Last month, a surfer off the coast of San Diego posted a video that went viral: waves breaking in electric blue cascades, each crest trailing ribbons of light like liquid stars. The comments filled with wonder and nostalgia—people remembered seeing this phenomenon as children, but swore it seemed brighter now. They weren't imagining things.

The Brightness Problem

Ocean acidification is making bioluminescent plankton glow more intensely. Tom Iwanicki, a PhD candidate at the University of Hawaii, presented findings in 2021 showing that bioluminescence can be up to 15% brighter in more acidic conditions. His team surveyed 49 records across multiple species and found that while effects vary by organism, the trend holds: as pH drops, many species shine more brilliantly.

This seems counterintuitive. We typically think of acidification as purely destructive—dissolving pteropod shells, bleaching coral, disrupting ecosystems. But bioluminescence operates on chemistry that happens to favor slightly more acidic conditions. Dinoflagellates, the single-celled organisms responsible for most surface ocean light shows, produce their glow inside tiny organelles called scintillons. These cellular structures need to become acidic internally to trigger the chemical reaction that creates light. When the surrounding seawater is already more acidic, that process becomes more efficient.

The ocean has absorbed roughly a third of human-generated CO2 since the Industrial Revolution. Pre-industrial pH sat around 8.2. We're now at 8.1. That decimal point shift represents a tenfold increase in acidity—pH is a logarithmic scale. NOAA projects we'll hit 7.67 by 2100 if current trends continue.

When Brighter Means Worse

Bioluminescence isn't decorative. Approximately 75% of pelagic organisms can produce light, and they use it for survival: attracting mates, luring prey, escaping predators. Some species release "glow bombs"—clouds of luminescent chemicals that distract attackers or attract larger predators to eat the immediate threat. Others use precise flash patterns as species-specific mating signals.

Changing the brightness disrupts this entire communication system. Imagine trying to have a conversation when everyone suddenly starts shouting. Predators that hunt by detecting bioluminescent flashes might find prey more easily. Prey species that use light to confuse attackers might become more visible instead. Mating signals could become indistinguishable from background noise.

The ecological consequences extend beyond individual interactions. Plankton produce half the world's oxygen and absorb half the planet's annual carbon emissions through the biological carbon pump. Phytoplankton at the surface absorb CO2 through photosynthesis, then sink when they die, carrying that carbon to the deep ocean where it stays sequestered for centuries. Woods Hole Oceanographic Institute estimates that turning off this pump would double atmospheric CO2.

Ocean acidification threatens this process from multiple angles. Some large plankton species that form the foundation of food webs and contribute significantly to carbon sequestration are already declining, according to Clare Ostle at the Marine Biological Association in Plymouth. Coccolithophores struggle to build their calcite shells. Pteropods—sea butterflies that feed everything from krill to whales—watch their shells dissolve in increasingly corrosive water.

The Sensory Environment Collapses

David Hutchins, a marine microbiologist at the University of Southern California, has spent years charting how plankton communities will shift. As waters warm, these organisms are migrating poleward at about 21 miles per decade. But they're not just moving—they're changing. The species composition of plankton communities looks different than it did fifty years ago, and the differences accelerate.

Altered bioluminescence adds another layer of disruption to what Hutchins and others call the marine sensory environment. Fish and marine mammals navigate by sound, chemical signals, and light. When the baseline brightness of bioluminescent displays shifts, it affects predator-prey dynamics, mating success, and spatial orientation. Some species might adapt. Many won't have time.

The taxa-specific nature of these changes makes prediction difficult. Some organisms show increased bioluminescence under acidification; others show decreased intensity or no change. The meta-analysis Iwanicki's team conducted revealed this variation clearly. We're not dealing with a uniform response, but rather a reshuffling of which species can signal effectively and which become either invisible or overexposed.

Watching From Space

NASA launched the PACE satellite in February 2024 specifically to monitor plankton changes from orbit. The spacecraft can identify different phytoplankton species by their spectral signatures and track bloom patterns across entire ocean basins. Early data shows bloom timing shifting earlier in the year at higher latitudes and intensity fluctuations that don't match historical patterns.

What the satellite can't measure yet is bioluminescence intensity. That requires in-water sensors or, more commonly, observations from boats and beaches. The viral videos and social media posts of glowing waves might actually serve as useful data points—crowdsourced evidence of changing brightness patterns. Researchers are beginning to take these observations seriously, correlating reported sightings with pH measurements and species composition data.

The Feedback Nobody Wanted

Ocean acidification creates a perverse feedback loop. Disrupting the biological carbon pump means less CO2 gets sequestered in the deep ocean, which means more stays in the atmosphere, which means more gets absorbed by surface waters, which increases acidification further. The ocean's buffer capacity—its ability to absorb CO2 without major pH changes—could decrease by 34% by 2100, according to NOAA research.

Brighter bioluminescence serves as a visible marker of this chemical transformation. Those electric blue waves aren't just beautiful; they're a symptom of an ocean under stress, its fundamental chemistry rewritten by the atmosphere above it. The glow intensifies as the system that produces it begins to fail.

We've known about bioluminescence since at least 500 BC, when observers first recorded the phenomenon. For most of that history, it remained constant—a reliable feature of night oceans. That constancy is ending. The lights are getting brighter just as the organisms producing them face an increasingly hostile environment. What looks like magic is actually a warning, written in light across darkening seas.