World Ocean Day 2023: 18 facts climate professionals should know

8th June 2023 is World Ocean Day, an awareness date aimed at drawing attention to the plight, vulnerability, and importance of the planet’s giant watery expanses, and the species and ecosystems that call them home. 

clear blue body of water

Professional and public-led events are taking place across the globe, and you can find a full official programme here along with more information about the aims and achievements of The Ocean Project, which coordinates the whole thing. 

In honour of the occasion, Environment Journal has teamed up with renewable energy and retrofit marketplace, GreenMatch, to collate 18 facts and statistics about the world’s oceans that everyone working in the climate sector needs to know. 

brown turtle on the ocean photography

Sea levels globally are rising by 3.7mm per year. By 2050, sea levels are predicted to rise by around 30cm. This will cause more coastal flooding and erosion.

Covering more than 70% of Earth’s surface, our global ocean has a very high heat capacity. (NASA)

Around 90% of global warming is occurring in the ocean. Heat stored in the ocean causes its water to expand, which is responsible for one-third to one-half of global sea level rise. (NASA)

The ocean has become a kind of ‘sink’ for our planet, absorbing around one-third of the carbon in our atmosphere. Before the Industrial Revolution, the ocean was actually a source of carbon, but the massive amount of CO2 now in the atmosphere has forced it to start absorbing the gas. (

The last 10 years were the ocean’s warmest decade since at least the 1800s. The year 2022 was the ocean’s warmest recorded year and saw the highest global sea level. (NASA)

The top 100 metres of the ocean show warming of 33 degrees Celsius since 1969.

The acidity of surface ocean waters has increased by about 30% since the beginning of the Industrial Revolution. This increase is directly caused by more carbon dioxide in the atmosphere and therefore more being absorbed into the ocean.

The effects of ocean warming include sea level rise due to thermal expansion, coral bleaching, accelerated melting of Earth’s major ice sheets, intensified hurricanes, and changes in ocean health and biochemistry.

Coastal cities around the world are affected by rising sea levels. Indonesia is moving its capital city away from Jakarta. Home to over 10 million people, Jakarta is one of the fastest-sinking cities in the world. Researchers predict that large parts of the city could be completely submerged by 2050.

Global sea levels rose about 20 centimetres in the last century. However, the rate in the last two decades is nearly double that of the last century and is accelerating every year.

Increased ocean temperatures have caused over half of coral reef cover across the world to be lost. This means the loss of biodiversity, habitats for fish and other species, and the natural barrier to sea storms for coastal communities.

A recent study suggests that approximately 14% of the world’s coral reefs were lost in 2008 and 2019 due to rising ocean temperatures caused by climate change, overfishing, coastal development, and declining water quality.

Scientists have estimated that coral reefs are at risk of being completely wiped out by 2050.

We have lost approximately 28 trillion tons of ice since the mid-1990s. Since then, each year, the planet loses 1.2 trillion tons of ice. This figure is hard to comprehend, but it roughly equates to around the same weight as all living things on earth – that is the quantity at which we are losing ice, every year.

Antarctica is losing ice mass (melting) at an average rate of about 150 billion tons per year, and Greenland is losing about 270 billion tons per year, adding to sea level rise.

Both the Arctic and Antarctic oceans recorded their second-smallest average annual sea-ice coverage during the 1979–2019 period of record. Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades.

This is important because the ice sheets of Greenland and Antarctica store about two-thirds of all the freshwater on Earth. They are losing ice due to the ongoing warming of Earth’s surface and ocean.

Meltwater coming from these ice sheets is responsible for about one-third of the global average rise in sea level since 1993. (NASA)

Glaciers are retreating almost everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska, and Africa. Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and the snow is melting earlier. (National Grid)

More on oceans: 

The Polluted Mermaid campaign highlights plight of marine life

Rapid sea heating could be evidence of ‘hidden climate risks’

More than 171 trillion plastic pieces have flooded the ocean

Historic high seas treaty agreement reached after decades of negotiations

Image: Christian Palmer (Top) / Jesse Schoff (Middle) / NASA (graphs)


Notify of
Inline Feedbacks
View all comments
Help us break the news – share your information, opinion or analysis
Back to top