Climate Change

Sea level rose 3.1 mm each year between 1993 and 2020: Report

Warming ocean waters have caused many marine species to move towards cooler waters, leading to introduction of non-native and invasive species to different marine ecosystems

By Susan Chacko
Published: Friday 24 September 2021

The global ocean, which covers 71 per cent of the Earth’s surface and regulates the Earth’s climate and sustains life, is undergoing severe changes from natural variations, over-exploitation and anthropogenic influences, a new report has flagged.  

These changes caused the sea level to rise by 3.1 millimeters each year on an average from January 1993 through May 2020, according to the report The Ocean State Report 5 by the Copernicus Marine Environmental Monitoring Service.

According to the report, between January 1993 and May 2020:

The warming of the world’s oceans and melting land ice caused sea levels to rise by 2.5 mm per year in the Mediterranean; 4.5 mm per year in Baltic Sea; 4.2 mm per year in western Pacific Islands; 1.7 mm per year in the Black Sea; 3.6 mm per year in the Iberian Biscay Ireland Seas; 2.9 mm per year in the North West Shelf; 3.5 mm per year Central Pacific Islands and 3.4 mm per year in Pacific Islands (total area).

The report showed that warming ocean waters have caused many marine species to move towards cooler waters; this migration has led to the introduction of non-native and invasive species to different marine ecosystems.

Increasing temperatures in the eastern Mediterranean basin saw the lionfish (Pterois miles) entering the Mediterranean Sea from the Suez Canal to the Ionian Sea.

A series of unprecedented and strong Acqua Alta (high water) events occurred in Venice in 2019, which contributed by an unusually high mean sea level, a high spring tide and extreme local and regional weather conditions. Water levels rose to 1.89 metres, the highest recorded level since 1966, flooding 50 per cent of the city between November 11 and 18, 2019.

In the Arctic, sea ice is steadily decreasing; in September 2019, sea ice followed a decreasing trend of -12.89 per cent per decade — a record low in sea ice extent in the last two years.

Around 50 per cent of Earth’s oxygen production takes place in the ocean, sustaining marine life cycles. This is threatened by growing human activities leading to climate change and eutrophication. This deoxygenates the oceans and seas and has adverse consequences on the marine life.

New tools, technologies to monitor warming ocean

Ocean temperature is increasing, influencing catches and marine species migration. Human pollution and overexploitation are affecting seawater quality, creating the need for a new indicator to measure seawater conditions.

The report suggested new tools for monitoring ocean changes: Forecast alert systems in Malta, prediction models for jellyfish blooms in the Mediterranean Sea and real-time monitoring programmes for tailored sea ice data. These tools can help scientists and policy-makers adapt to a changing ocean on a local, regional and global scale.

The new Maltese tracking system provides alerts and near-real-time evolution of potentially extreme ocean and weather conditions. In 2019, it helped local authorities improve land and marine protection, providing guidance for safe ocean navigation and relaying critical information to emergency units during severe ocean and weather events.

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