Sea level rise: a problem that affects everyone

In 2023, the global mean sea level reached a record high in satellite data, reflecting the continued warming of the oceans and the melting of glaciers and ice caps. The rate of increase in global mean sea level over the past decade is more than double the rate of sea level rise in the first decade of the new Millennium.

The daily average water temperature reached 20.96 degrees Celsius in August 2023: this is the highest figure ever, even higher than the record of March 2016 when 20.95 degrees were recorded. This is confirmed by the Copernicus Climate Change Service. This effect means less carbon dioxide absorption, melting glaciers and serious threats to the marine ecosystem. In addition, an international study recorded a record increase in the heat content of the oceans in 2023, with ten Zetta Joules more than in 2021, equivalent to about one hundred times the world’s electricity production in 2021: in just a few years, the rate of temperature rise has increased by 24%.

The impacts are manifested on a global scale: from threats to the coral reefs of the Mediterranean to the rapid warming of the Gulf of Mexico. Alarmed scientists attribute this ocean warming to climate change and the resulting increase in greenhouse gas emissions. Rising ocean temperatures are strongly affecting the ability of the oceans to regulate the Earth’s climate, causing coral reefs to decline and endangering biodiversity. The rising temperature of the oceans is a major problem for the species that live there, because it affects the food chain and the balance of marine populations. For example, due to unfavourable environmental conditions, organisms migrate to cooler areas and some fish species risk extinction altogether.

In this context, the scientific community focuses on investigating the causes of this unprecedented warming. Although the influence of the El Niño phenomenon (a climate pattern that describes the unusual warming of surface waters in the eastern Pacific Ocean) is recognised, it does not fully explain the current warming, which is mainly fuelled by increasing greenhouse gas emissions. Seas and oceans are essential for maintaining the balance of living ecosystems. Besides absorbing a quarter of all the carbon dioxide released into the atmosphere, they emit more than half of the oxygen we breathe, which is why they are often referred to as the ‘lungs of the Earth’. If the temperature of the oceans rises, less carbon dioxide is absorbed. As a result, this greenhouse gas will be more present in the atmosphere, giving rise to a self-sustaining mechanism.

It is the Mediterranean that confirms itself as the fastest warming basin among those analysed in the study. The heat content in 2022 will be at the same level as in 2021, according to estimates by the Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP-CAS).

It is news in recent days that the world’s largest iceberg is moving beyond Antarctic waters after being stranded for more than 30 years. The iceberg, known as A23a, separated from the Filchner Ice Shelf in the Antarctic in 1986, but has remained attached to the ocean floor and remained in the Weddell Sea for many years. According to the latest satellite images, A23a, weighing almost a trillion tonnes, is rapidly drifting past the northern tip of the Antarctic Peninsula, aided by strong winds and currents. Its size is remarkable: it is about three times the size of New York City and more than twice the size of Greater London, one of the two ceremonial counties of the British metropolis. Its surface area is four thousand square kilometres.

The need for action against the climate crisis emerges as a matter of urgency from the serious scientific evidence, as continued ocean warming irreversibly threatens marine ecosystems and the overall well-being of the planet. The call for immediate action is essential to counter this critical situation.