My parents’ marriage was illegal in Maryland in 1966, so they moved west. By the time I was born in 1973, they had settled in Monterey County, California — the same year the last cannery on Cannery Row shut down. The Hovden Cannery closed its doors, marking the end of an era. Where it stood, the Monterey Bay A q u a r i u m would later rise, a monument to what had been lost and what we hoped to restore. 

When I was 12, in 1985, I became a guide at that aquarium — the youngest in my class. Standing in a building literally constructed on cannery ruins, I told visitors about kelp forests, sea otters and the remarkable return of the sardines. Through the 1980s and 1990s, they came back. The ocean, given a chance to rest, proved resilient. 

As a kid who often felt out of place, the ocean was my refuge. I learned it can be a patient teacher. But the lesson it’s teaching now, according to leading scientists, is one humanity may never recover from. Worse, its impact will reach far beyond our coasts — first with rising seafood costs, then with far more serious consequences. 

Last week, scientists announced the world has reached its first climate tipping point. Coral reefs — supporting a quarter of all marine life and nearly a billion people — are in widespread, irreversible collapse. Since 2023, more than 80% of the world’s reefs have suffered the worst mass bleaching event ever recorded. 

This is different from the sardines. When sardine populations crashed in the 1940s and 1950s, the fish survived elsewhere. When fishing stopped, they returned. Recovery took decades, but it was possible. 

Coral reefs are the foundation. When they die, the habitat disappears. The three-dimensional structures that provide shelter, feeding grounds and nurseries collapse into rubble. Unlike sardines, reefs take centuries or even millennia to rebuild — if they can at all under continued warming. 

Scientists warn we’ve crossed a threshold. Unless global temperatures drop to just 1 degree Celsius above preindustrial levels — not just stop rising but actually decrease — these ecosystems will be lost. Small refuges may survive, but vast, thriving reefs will vanish on any timeline that matters to our children. 

That’s just the first domino. The same report warns other catastrophic tipping points are near — the Amazon rainforest, Atlantic ocean currents that regulate global weather, and the ice sheets controlling sea levels. Each could trigger others in a cascade of irreversible changes. 

These aren’t distant problems. The Atlantic Meridional Overturning Circulation, which includes the Gulf Stream, could collapse within our lifetimes. If it does, global food production could face devastation. Nearly 60% of land suitable for wheat and corn would become unusable, threatening agriculture, spiking prices and fueling hunger worldwide. 

These changes are not for our grandchildren — they’re happening within decades. 

Still, we have agency. Scientists say there are positive tipping points, too. Solar power is now cheaper than coal, and electric vehicles are rapidly expanding. 

Next month, world leaders meet in Brazil for COP30, the annual climate summit where countries pledge to cut pollution. For farmers, fishers and families everywhere, it matters. If nations commit to rapidly ending coal, oil and gas use, we can slow the damage. If not, we face soil that won’t grow crops, water that won’t arrive when needed and weather that destroys entire harvests. 

The remaining healthy coral pockets must be protected from pollution and overfishing. And we need to remove carbon from the air, not just stop adding more — like pumping water from a flooded basement. 

As that 12-year-old aquarium guide, I taught visitors about resilience and recovery. Sardines taught me the ocean can heal when we give it a chance. But coral reefs teach a harder lesson: Some thresholds, once crossed, can’t be undone. 

The ocean has been a patient teacher. But this lesson — about irreversible tipping points and cascading collapse — is one we cannot afford to fail. The consequences won’t stay in the ocean. They’re coming for all of us. 

The writer is a professor of practice at the University of Pennsylvania.