When the Sea Becomes a Desert

(A juvenile Brown Pelican( Pelecanus occidentalis)attempting to eat fish scraps, seabirds resort to scavenging on shore when prey shifts too deep into cold waters during marine heatwaves:Wildlife Rehabilitation Documentation.)

You might have seen the images. Emaciated seabirds washing ashore, their bodies too weak to lift off the sand. Brown pelicans, cormorants, and other coastal birds that should be soaring over the water are instead stumbling onto beaches and collapsing from exhaustion. It is happening across the world, and the cause is not a mystery.

The seabirds are starving because their food has moved beyond their reach. Marine heatwaves have driven prey like krill, anchovies, and sardines into deeper, colder waters. Many seabirds, such as brown pelicans, can only dive a few feet.They simply cannot reach the fish that used to be near the surface. The warm water has also reduced the cold, nutrient-rich upwelling that sustains the entire food web. Without those nutrients, the small fish that seabirds depend on become scarce. The birds are left with empty stomachs and no options. Some have been seen walking to shore to die within minutes, too exhausted to even fly.

The crisis stretches across the North Pacific and beyond.

Between 2014 and 2016, a severe marine heatwave known as the "warm blob" devastated seabird populations across Alaska and the Pacific Northwest. An estimated 4 million common murres died, representing over half of the state's population. Carcasses washed up from California to Alaska, and years later, the population has still not recovered.

(Common murre (Uria aalga) carcasses piled  along an Alaskan coastal shoreline following severe starvation and exhaustion during a marine heatwave: National Park Service (NPS)

 At the same time, between 250,000 and 500,000 Cassin's auklets starved to death from California to British Columbia. The heatwave had reduced the nutritional quality of their zooplankton prey, leaving them without the energy to survive.

(view of live marine zooplankton, including copepods, larval fish (top right), and various small planktonic crustaceans drifting in dark ocean water: NOAA (National Oceanic and Atmospheric Administration)

In the Northwest Atlantic in 2022, a sudden cold snap and sea-ice changes led to the starvation of thousands of thick-billed murres off Canada's coast. In the UK and Europe, thousands of seabirds, including puffins and guillemots, have died in mass mortality events linked to winter storms that left them exhausted and starved. In the Mediterranean, an unusual die-off of razorbills has been reported, with starvation as the primary cause. The pattern is the same everywhere: heat disrupts the food web, and the birds die.

So what causes these heatwaves? The immediate triggers are natural. Stalled high-pressure systems act like a lid, trapping heat and calming winds. Weakened ocean currents fail to mix cooler deep water with the warm surface layer. Natural cycles like El Niño redistribute warm water across the Pacific. But these natural events are now amplified by something far larger. The ocean has absorbed about 90 percent of the excess heat from global warming.

(infographic illustrating how global warming and a stalled atmospheric heat dome form a marine heatwave.)

Climate change has made marine heatwaves three times more frequent and longer-lasting than they were in the 1980s. What used to be a rare event is now routine.

The seabirds do not know this. They do not understand climate policy or carbon emissions. But they know something is wrong. They feel it in the warmer water, in the empty hunting grounds, in the hunger that does not go away. They swim, hunt, and raise their young in a world that is warming around them. And when the fish move deeper, they cannot follow. When the storms hit, they cannot recover. When the heat stays, they starve.

These birds are not just victims. They are indicators, living warnings of a system under stress. Their deaths tell us something we already know but often ignore: the ocean is changing faster than its inhabitants can adapt. And if we do not act, the beaches will keep filling with the bodies of birds that had nowhere else to go.

(A large colony of Common Murres (Uria aalge) densely crowding rocky coastal cliffs, with dozens of birds taking flight in a dense flock over churning ocean waves below.: U.S. Fish and Wildlife Service (USFWS)

What do you think? At what point do we stop seeing these mass deaths as isolated tragedies and start seeing them for what they are — the cost of a world we chose not to cool down? 🕊️