World Meteorological Day: Why the oceans are more important than you might think

Watch Laura Tobin talk about World Met Day and why the oceans are so important on 24th March 2021

This year's World Meteorological Day, 23 March 2021, has been devoted to the oceans, our climate and weather.

It celebrates the WMO's focus for understanding the connection between the ocean, weather and climate within the Earth's system.

Our climate is warming and this, in turn, is warming the world's oceans, which drive our weather climate - a coupled system.

In the latest annual report from the WMO Global State of the Climate, it shows the year 2020 was in the three warmest years on record, despite a La Niña year which has a cooling effect on the Pacific Ocean. Furthermore, the last decade, 2011-2020 was the warmest on record.

Ocean temperature at varying depths as an ensemble from governing bodies. 0-700m (blue), 0-2000m (yellow) and 700-2000m depth layer (green) Credit: WMO

Around 90% of the excess energy that accumulates in the earth system due to increasing concentrations of greenhouse gases, goes into the ocean.

The Ocean Heat Content (OHC) is a measure of this heat accumulation in the Earth system. It is measured at various ocean depths, up to 2000m deep. Looking at the graph above it's evident that all data sets agree that ocean warming rates show a particularly strong increase in the past two decades and across all depths.

The oceans cover 70% of the Earth's surface, driving weather and climate. They play a vital role in climate change and are a major driver for the world's economy - carrying more than 90% of the world trade according to the WMO.

Around 40% of people worldwide live within 100km from the coast and as the planet warms sea levels will rise. 90% of the suns energy is absorbed by the oceans, whilst only 2.3% is absorbed by the atmosphere. The rest melts snow and ice and warms the land.

But what's next? Eventually, much of the ocean’s newly absorbed heat will flow out into the atmosphere over the coming centuries. This will exacerbate the global climate, warming it further.

The impacts of this are:

  • Excessive heat contributes to sea level rise due to thermal expansion

Declining Arctic Sea ice In the Arctic has been observed since 1980 Credit: WMO
  • Melting of sea ice - which reflects solar energy back into space helping to cool the planet. Without this, the planet will warm further

Global mean surface pH from 1985-2020. The shaded area indicates the estimated uncertainty in each estimate Credit: WMO

  • As carbon dioxide goes up, it affects ocean chemistry. Lowering the pH makes the oceans more acidic, destroying coral reefs and reducing aquatic biodiversity. This has a positive feedback as more acidic oceans can absorb more CO2

  • Ocean acidification affects many organisms and ecosystem services, it makes inhospitable environments for marine life, threatening food security by endangering fisheries and aquaculture. It also affects coastal protection by weakening coral reefs, which shield coastline

  • In 2020 warm ocean temperatures helped fuel a record Atlantic hurricane season

Global Mean Seal Level from 1993 to 2020 has been rising at about 3.3 millimetres per year Credit: NASA
  • Sea level rise : Globally, the sea level are rising and have gone up by +71.3mm since the year 2000. Although this might not sound like very much it took nearly 60 years to rise the same amount before that. It's this rapid change that is most worrying.

Climate Refugees

Sea level rise impacts us most directly. Not only by coastal erosion, but also storm surges travelling further inland from hurricanes. It's sea level rise that is creating climate refugees. These are people and communities who have to uproot and relocate as a result of the impacts from climate change.

Isle de Charles, Louisiana Credit: Carolyn Van Houten/National Geographic

Around the world the impacts of sea-level rise are profound. The people from Isle de Jean Charles in Louisiana were announced as the first climate refugees. The Bayou State loses about a football pitch worth of land to erosion every 90 minutes.

Since 1955, the Isle de Jean Charles, a sliver of island 80 miles southwest of New Orleans, has shrunk by 98%. The isle continues to slip into the Gulf of Mexico, making living here increasingly difficult.

But that won't happen in the UK you say? Wrong.

Residents of Fairbourne, a village in Gwynedd have been in the news more and more and they, have been labelled the UK’s first climate refugees.

Happisburgh coastal erosion in Norfolk Credit: PA

The government announced they would have to leave their homes. They’ve been told the area - 450 houses, a pub, post office and several shops - will be decommissioned by 2054 because of the threat of sea-level rise and coastal flooding linked to climate change.

It's devastating for the residents, who's properties values have plummeted. Residents don’t know when or where they will have to move, who will pay, and they haven’t been offered any compensation. Gwynedd Council says: “In the long term, maintaining and increasing flood defences would not only be costly but would also lead to increased risk to life should the defences fail.”

In England 1.5 million homes are at risk of flooding by 2080 & 100,000 homes at risk of coastal erosion

Credit: Pixabay

We have a lot to thank the oceans for, our weather, the rain, the water we drink and for absorbing carbon dioxide and heat. There is still hope the UK, EU, China and America's net-zero pledges by 2050 will help to make a difference to the global climate. Find out more about what you can do by visiting for more details