Dwain Northey (Gen X)

When we talk about climate change, the conversation usually points toward the Amazon rainforest—the so-called “lungs of the Earth.” We hear about the tragedy of deforestation, the destruction of carbon sinks, and the loss of biodiversity. While those are critically important issues, focusing almost exclusively on forests hides a much larger, often overlooked truth: the oceans are the planet’s greatest carbon sink. Plankton, algae, and other marine microorganisms absorb more carbon dioxide and produce more oxygen than all the world’s forests combined. Yet, the ongoing warming of our oceans is undermining this capacity at an alarming rate, perhaps even faster and more severely than deforestation on land.

The scale of this is staggering. Phytoplankton—microscopic, plant-like organisms that drift with ocean currents—perform photosynthesis just like trees do. In the process, they absorb enormous quantities of carbon dioxide and release oxygen back into the atmosphere. Scientists estimate that these oceanic organisms are responsible for producing at least half, and possibly as much as 70 percent, of the oxygen we breathe. Compare that to the Amazon, which contributes less than 10 percent, and suddenly our fixation on forests alone seems deeply incomplete.

The oceans not only produce oxygen but also lock away carbon. Through a process known as the “biological pump,” plankton absorb carbon dioxide at the surface and, when they die, carry some of that carbon to the deep ocean, where it can remain trapped for centuries or even millennia. This invisible, constant carbon capture system dwarfs the capacity of terrestrial forests. Without it, atmospheric carbon levels would be dramatically higher, and Earth’s climate would already be far less habitable.

But here’s the problem: global warming is sabotaging this system. Rising sea surface temperatures inhibit plankton growth, because warm waters stratify and reduce the mixing of nutrient-rich waters from below. Without those nutrients, plankton populations decline. Warmer oceans also hold less dissolved oxygen, further stressing marine ecosystems. Add acidification from carbon absorption, which makes it harder for organisms like plankton and shellfish to build their calcium carbonate structures, and the result is a cascading collapse of the very foundation of the marine food web.

The consequences ripple outward. Fewer plankton mean less carbon absorption, accelerating climate change in a vicious feedback loop. Declining oxygen production directly threatens the balance of life on Earth, while marine ecosystems from coral reefs to fisheries suffer devastating losses. These disruptions are happening now, not in some distant future. Ocean “dead zones”—areas so depleted of oxygen that they can no longer support life—are already expanding worldwide, directly linked to warming and pollution.

And yet, global discourse is tilted heavily toward forests. That’s not to say reforestation and halting deforestation aren’t urgent—they are. But it’s dangerously misleading to pretend that saving trees alone will stabilize our climate. If we fail to protect our oceans and the microscopic engines that drive them, all the tree planting in the world won’t offset the collapse of the largest carbon sink on the planet.

A shift in focus is overdue. Protecting marine ecosystems, reducing ocean pollution, curbing greenhouse gas emissions, and funding research into ocean health must stand alongside forest conservation in climate policy. The oceans are our true lungs. If we neglect them, we’ll find ourselves gasping for air in more ways than one.