An array of new technologies and methods are leading to rapid progress in oceanography — the physics and chemistry of the ocean. Automated sensor arrays are enabling us to trace systems of currents and nutrient flows in unprecedented detail. Deep-sea exploration is revealing how the ocean interacts with the solid Earth, notably in hydrothermal vents where mineral-rich water spews up from beneath the seabed. The ocean is becoming understood as a vast engine of currents and chemical flows that is inextricably linked to wider Earth-system processes such as plate tectonics and the climate.¹

This understanding is crucial because of the sheer power of the ocean. As global average temperatures continue to rise, the ocean is responding in complex ways: sea ice is melting and retreating, currents are slowing and shifting their paths, and stored heat is moving. Our growing understanding of oceanography will enable us to identify the most significant and pressing risks, and to devise ways to mitigate them.

Likewise, our knowledge of marine biodiversity is progressing rapidly, driven by technologies like eDNA and metagenomics. At the same time, our understanding of marine ecosystems and the services they provide is also increasing, enabled by uncrewed vehicles and other tools for large-scale ocean observation.

This knowledge is crucial to the well-being and prosperity of society. We already know that non-sustainable human activities pose multiple threats to key marine ecosystems in the deep sea, coral reefs, seagrass meadows and the Arctic sea-ice biota. Our improving understanding of those ecosystems offers an opportunity to find better ways to conserve them — and thus to protect the natural services they provide, ranging from food provision to climate regulation.

The ocean can also offer opportunities, when managed sustainably. Whilst the impact of large-scale industrial implementations is not yet understood and thus must be developed with great caution, the emerging "blue economy" sectors may provide renewable energies, store carbon (marine carbon-dioxide removal, or mCDR), provide food or harvest marine genetic resources.

KEY TAKEAWAYS

Earth’s oceans are a major and vital part of the planet’s ecosystem, generating 50 per cent of oxygen, absorbing 90 percent of excess heat and capturing 25 percent of CO₂. However, much of the detail of their characteristics, contributions and changing properties are not yet understood. The field of Oceanography aims to inform our understanding of the physics and chemistry of the oceans, such as those involved in currents, helping us to model and forecast the effects of a changing climate and the potential for tipping points to cause major change. Researchers are still gathering new information on Ocean biodiversity, including microbial marine life as well as plants and animals living in the water and on and in the sea-floor (where an estimated 90 per cent of species are yet to be discovered). Research is also uncovering the details of Ecosystem functions. The services that the diverse deep-sea ecosystems, as well as plankton, seagrass and corals in shallower seas, bring to the ocean system remain largely unexplored, and further insights will be vital to conservation efforts. All of this can inform understanding of Human impact and ocean stewardship and facilitate better outcomes for the ocean environment and dependent life in the face of climate change and other challenges.