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One ocean, one climate

Our planet is covered in large part by water. Historically, the ocean was referred to as four oceans (Atlantic, Pacific, Indian, Arctic) or five if you included the Southern Ocean (around Antarctica).  

For the ocean science community, it is now accepted there is only one global ocean- and many basins with individual names – says Christine Pequignet, a Met Office senior ocean forecasting scientist.  

There are scientific reasons for this, and important societal consequences. Of course, if you swim off the coast of Hawaii after a lifetime of swimming in the water around Scotland, it will be difficult to recognise that you are in the same ocean. Yet, every ocean basin is connected to at least two others.  

The shape of the ocean basins results from the evolution of one single supercontinent, Pangaea, which was surrounded by one super-ocean called Panthalassa. Like then, the forces that act upon the ocean today know no boundaries, for example the wind, gravity, the earth’s rotation. The resulting circulation of water moves energy, organisms and matter – including pollution – around the globe.  

The most common map projections, used to represent the earth on a flat surface, typically focus on land and divide the ocean. However, there are other map projections which instead focus on the ocean, such as the one here to display sea surface temperature, which highlight the inter-connection of the five ocean basins.

A unique and ocean-centric visualisation of the globe surface underlining the one ocean concept.

Map of Sea Surface Temperature plotted on a projection that emphasises the continuous nature of the world ocean (source: Philip Brohan Met Office)

The images we choose, the words we use, all contribute to the perception we have of the world and how we feel about it and how we act.

Talking about a global ocean reinforces the need to approach ocean issues in a universal manner. Knowing that actions on the ocean have both local and global impacts connects us to other communities and reinforces the critical need to protect the marine environment everywhere.  

The ocean is a critical element of the climate system. At a time when the climate is changing at a rapid rate, it is even more important to draw attention to the uniqueness of the ocean and the importance of its role in influencing our planet’s climate. Noone questions the singular use of climate, despite the large range of climates observed around the globe and the variability in impacts that climate change will generate. Climate and ocean processes and issues are global. Along with one climate, there is one ocean.  

During April we will be exploring the topic of the ocean and climate. Follow the #GetClimateReady hashtag on X (formerly Twitter) to learn more throughout the month.

Discover more about the one ocean concept.


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