A new level for sea change science


A new level for sea change science Austin Neill / Unsplash

PML has been involved in a Europe-wide effort to improve the accuracy of a dataset that provides vital information on global sea level changes, as published in Earth System Science Data Journal.

As sea levels rise, more coastal communities come under threat of flooding, ranging from popular tourist destinations, such as the islands of the Maldives, to large areas of coastal European countries, such as the Netherlands and Belgium.

Sea level change is one of the many variables tracked by the European Space Agency’s Climate Change Initiative since its establishment in 2010. It is a key indicator of climate change, as sea level rise is widely acknowledged as an effect of warmer oceans and an increase in melting of glaciers and sea ice. Sea surface elevation is measured by  altimeters, with instruments around 1000km above the planet determining sea level to within just a few centimetres.

The task of monitoring sea level change, however, is challenging. The past two decades have seen many different instruments contributing data, each with its own uncertainties and caveats. A large number of research labs across Europe have co-ordinated their efforts to improve the atmospheric, oceanographic and instrumental corrections to produce a consistent dataset of sea level spanning 23 years. Preliminary observations suggest that although major climate phenomena such as El NiƱo can unsettle the global mean sea level, there is still a clear rise of 3.2mm per year since recording began.

“This project brought together expertise in satellite processing from research labs throughout Europe,” said PML’s Dr Graham Quartly, lead author on the paper. “This is a triumph not just of the technology involved but also of the effort of many scientists from a wide array of countries to determine all the corrections.”

“The six years spent on this project have allowed a thorough reappraisal of everything from orbits to tide models,” continued Quartly. “These data are being combined with temperature and salinity measurements to investigate long-term changes in the ocean.” 

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