What Future for the Ocean and Human Societies?

To mark World Ocean Day and in connection with the United Nations Ocean Conference (UNOC), the Office for Climate Education (OCE) presents a series of four articles to explore the theme “Ocean and Climate” in the classroom.

After exploring thermal regulation, the ocean’s role as a heat sink, and carbon sequestration, this fourth and final article focuses on marine biodiversity and the multiple interactions between the ocean and human societies in the context of climate change.

• A Vulnerable Reservoir of Biodiversity

The ocean hosts remarkable biodiversity, often concentrated in very specific ecosystems known as ecological niches, such as coral reefs. Microscopic, single-celled, photosynthetic organisms called phytoplankton form the base of most marine food chains and are consumed by —often microscopic animals— zooplankton. At the top of these food chains are sharks and marine mammals, such as seals and whales. Any change within this chain has repercussions throughout the entire food web.

Therefore, ocean acidification, deoxygenation, marine heatwaves, and pollution represent direct or indirect threats to the entire marine biodiversity, especially since the speed of these phenomena does not allow species enough time to adapt.

Educational Resource:

• "Ocean Food Webs" Multimedia Activity

• Human Societies Closely Linked to the Ocean

The ocean plays an indispensable role in the lives of millions of people around the world, economically, culturally, and socially.

It is estimated that 600 million people globally depend at least partially on fishing and aquaculture for their livelihoods. These activities provide both direct employment and a critical food source, especially in coastal areas.

In many regions, marine tourism is by far the largest ocean-based employment sector. Fishing, aquaculture, shipbuilding, boat repair, and maritime transportation of passengers and goods are also major economic sectors.

The ocean is also a source of energy—renewable, through wave and tidal energy, and non-renewable, through the extraction of oil, gas, and minerals from seabed rocks.

Globally, 37% of the population lives within 100 km of the coast, making coastal communities especially vulnerable to the effects of climate change, while being deeply connected to ocean health.

Finally, the ocean holds a significant place in cultures and collective imagination: it is ever-present in literature, oral traditions, sea festivals, sailor songs, folktales, myths, and major international nautical events.

• Consequences of Climate Change

Climate change profoundly alters oceanic balances, with major impacts on coastal populations and economies that rely on them.

Sea level rise, combined with stronger storms, increases the frequency of extreme sea-level events, such as once-in-a-century floods. These phenomena are especially concerning for populations living in low-lying coastal zones, which account for about 10% of the world population. These areas are highly exposed to submersion and erosion risks.

The disappearance or decline of marine species—especially linked to ocean acidification and the increase in marine heatwaves—disrupts ecological balance and affects fishing communities, who depend directly on these resources for food security and economic activity.

Slowing down sea level rise, or any other consequence of climate change, would provide more room for action to adapt territories and preserve human activities. This highlights the urgent need to reduce global greenhouse gas emissions.

Educational Resources:

• “Marines Energies” explained by Raphaël Gerson
• Consequences of Climate Change on Ecosystem Services
• Human activity, ocean & cryosphere
• Increasing Beach Resilience to Climate Change

The ocean plays a vital role in climate regulation, biodiversity, and human societies. Understanding it helps us better grasp the impacts of climate change and the need for action. It is a rich, cross-disciplinary topic—ideal for fostering systemic thinking in the classroom.

Climate change education is a powerful lever to raise awareness and inspire action to preserve the ocean.