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Yesterday the United Nations celebrated World Oceans Day, which this year was dedicated to the role of women in the relationship with the ocean, a subject on which there is still very little data and research.

The day aims to raise awareness about the impact of human actions on the oceans and to push for global measures in sustainable management of the seas, sustainable development goals of the 2030 Agenda, and the action program signed in September 2015 by the governments of 193 UN member countries.

Every year around 8 million tons of plastic end up in the ocean, values ​​increased tenfold since 1980. In addition to pollution, climate change also represents a real threat to marine biodiversity: it could lead to a decrease in the presence of fish ranging from 3% to 25% by the end of the century, depending on how effective the actions against rising temperatures. A consequence that would have direct repercussions on over 3 billion people for whom fish is the main source of protein and for over 200 million workers employed in fishing activities.

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Rainwater, drinking water, the climate, the coastal environment, much of the food and half the amount of oxygen we breathe are regulated by the oceans. Today their balance is in danger due to climate change, over-fishing and pollution, especially that caused by plastic. The oceans are heating up faster than expected, their level is rising due to the melting of the glaciers, carbon dioxide is making the water more acidic, resulting in damage to coral reefs, and many marine species are threatened with extinction.

The “heart of the Earth” (how the UN defines the oceans) is fundamental for the survival of the human being and of all the species that live on the planet, and for this it must be protected and safeguarded. Warmer oceans In the last century the use of fossil fuels such as coal and oil has increased the concentration of carbon dioxide (CO2) in the atmosphere, causing the intensification of the greenhouse effect, or the ability of the atmosphere to trap heat radiated by the Earth to space and warm up. About 93% of the excess heat created by human activities is absorbed by the oceans who are experiencing an increase in average temperatures.

According to the Ocean State Report, the global sea surface temperature increased between 1993 and 2015 with a rate of 0.016 degrees Celsius per year. There have been increases in practically many regions: +0.04 degrees Celsius in the Mediterranean, +0.08 in the Black Sea, +0.03 in the Baltic Sea. Rising temperatures are able to alter the currents and change the air-sea cycle with repercussions on the weather and on the frequency of extreme events such as floods, storm surges, hurricanes and storms. Marine species at risk The increase of one degree or even half a degree of ocean temperature could also cause devastating effects on oceanic biodiversity. Some species could migrate to new territories to save themselves, others – those that cannot move, such as corals – would simply die with serious consequences on the entire ecosystem. Melting ice Due to warming and melting glaciers, the level of the oceans rises. Since 1993, every ten years, almost 780,000 square kilometers ( 6.2%) of Arctic glaciers have been lost, causing an increase in the ocean level of 3.3 millimeters each year (in the Mediterranean Sea of ​​2.7 millimeters). Since 1900 the average global sea level has increased from 16 to 21 centimeters. The oceans carry out the important task of mitigating the impacts of atmospheric pollution because they absorb about 30% of the CO produced by human activities.

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But the price we pay for this carbon dioxide storage is water acidification. When CO is absorbed, a series of chemical reactions are triggered that change the pH of the oceans. If greenhouse gas emissions were to continue at current levels, the oceans will become 150% more acidic in the next century, reaching a pH level never seen in the last 20 million years.  Coral reefs in danger Due to acidification, the oceans are also losing important chemical elements for the formation and survival of animals such as molluscs, sea urchins, plankton and corals. Coral reefs occupy about 1% of the marine environment but are fundamental for a healthy ecosystem and for all other life forms because, literally, they build their habitat.

According to the scientists, the global strategies for biodiversity conservation promoted by the United Nations in the future will not only have to deal with restoring the integrity of areas already compromised by human action, but will have to commit themselves to promoting protection actions towards the pristine natural areas off international waters. Their protection will contribute to preserving large marine ecosystems, migrating species and those living in circumscribed territories.

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