Rising sea levels will become a genuine threat for 150 million people living in coastal areas around the world, according to a new international study.

The study ‘Trends and acceleration in global and regional sea levels since 1807’ found convincing evidence the sea level has been rising over the past 200 years – and continues to rise.

Warming of the ocean and the melting of the glaciers and ice sheets are the cause of the sea level rise, said Dr Svetlana Jevrejeva from the UK’s National Oceanography Centre (NOC), who co-authored the scientific research paper.

Dr Jevrejeva said:

 “There is a huge inertia in the climate system, so even if we stop the warming of our planet now - if we stop emitting greenhouse gases into the atmosphere today – the global sea level will continue to rise for the next few hundred years. We are facing a colossal challenge - to deal with carbon emissions as soon as possible.”

With about 150 million people living within one metre of high tide globally, sea level rise is one of the most damaging aspects of a warming climate. The vulnerability of extensively populated coastal areas, the threats to infrastructure, and population migration are major concerns for society.

UK must make hard decisions on which coasts to protect – and abandon

Dr Jevrejeva continued:

“Fifteen of the world's 20 megacities, with populations of more than 10 million, are sensitive to sea level rise and increased coastal storm surges. Soon we will have to make very hard decisions in the UK and globally: which coastal area is going to be protected and which could be abandoned? It means that as a civilization we are not able to protect some of our cultural heritage, unique beaches and cliffs.”

Co-authors on the paper are JC Moore from the Beijing Normal University in China, A Grinsted from the University of Copenhagen in Denmark, AP Matthews from NOC and G Spada from the Dipartimento di Scienze di Base e Fondamenti, Università degli Studi “Carlo Bo” in Urbino, Italy.

The study looked at global sea level reconstruction based on 1,277 tide gauge records dating from 1807 to 2010. Tide gauge observations suggest that sea level rose by 6 cm during the nineteenth century, 19 cm during the twentieth century, and the sea level has continued to rise this century. Over the past 2000 years, sea level was almost stable but since the 1800s it has started to rise.

The researchers used the historical tide gauge records collected by the Permanent Service for Mean Sea Level (PSMSL), to understand the past sea level rise.

Based in Liverpool at the National Oceanography Centre and established in 1933, the PSMSL has been responsible for the collection, publication, analysis and interpretation of sea level data from the global network of tide gauges. It All of PSMSL’s data are available from the web page http://www.psmsl.org/data/.

PSMSL data have been employed intensively in studies such as those of the Intergovernmental Panel on Climate Change (IPCC).

The National Oceanography Centre is the UK’s leading institution for integrated coastal and deep ocean research. Working with its partners NOC provides long-term marine science capability including: sustained ocean observing, mapping and surveying; data management and scientific advice.

The Centre, which is wholly owned by the Natural Environment Research Council,  operates at two sites, its Southampton HQ and Liverpool.

Click here to read the study in full.