Why the Ocean Matters to Every Breath You Take

When people think about the sources of oxygen on Earth, they usually picture forests. Trees matter enormously, but a large share of the oxygen we breathe comes from somewhere far less visible: the ocean.

Tiny organisms, huge impact

Phytoplankton are microscopic plant-like organisms that drift near the ocean surface. Like land plants, they use sunlight to turn carbon dioxide and water into energy, releasing oxygen as a by-product. Scientists estimate that marine photosynthesis produces roughly half of the oxygen generated on the planet each year.

A giant climate regulator

The ocean also absorbs a significant portion of the carbon dioxide released by human activity, as well as most of the extra heat trapped in the atmosphere. This slows the pace of climate change, but it comes at a cost.

Warming and acidification

As the ocean absorbs more carbon dioxide, the water becomes more acidic. This makes it harder for creatures such as corals and shellfish to build their skeletons and shells. Warmer water also holds less oxygen, which affects fish and other marine life.

The food web begins here

Phytoplankton are the base of the marine food web. Tiny animals called zooplankton eat them, small fish eat the zooplankton and larger animals follow. When phytoplankton populations shift, the effects can ripple all the way up to whales and seabirds.

Currents that connect the world

Ocean currents move heat from the tropics towards the poles, shaping weather patterns across continents. Changes in these currents can influence rainfall, storms and temperatures far from any coastline.

What we can do

Protecting the ocean involves large-scale action such as reducing emissions and creating marine protected areas. Individuals can help too by reducing single-use plastics, choosing sustainably sourced seafood and supporting organisations that monitor ocean health.

A shared responsibility

Whether you live by the sea or hundreds of kilometres inland, the ocean affects your air, your weather and your food. Understanding that connection is the first step towards caring for one of the most important systems on our planet. Every breath is, in part, a gift from the sea.