” If the Ocean is a world library whose books
contain a profusion of solutions for the survival of humanity,
the vast majority of its books remain ignored, having never been read ”.
Maud Fontenoy
The Ocean is getting warmer
With its great thermal inertia -compared to that of the atmosphere and the continents-, the Ocean has absorbed more than 90% of the heat stored by the Earth since 1970.
According to the 2019 report of the Intergovernmental Panel on Climate Change (IPCC), the World Ocean has been warming relentlessly since 1970. As for the UN's observation, it is irrefutable. The 2015-2018 period has broken all records for heat and the warming of the upper layers of the Ocean has doubled in fifteen years compared to the last sixty years as a whole. This is an exponential acceleration that makes it more difficult for CO2 to dissolve in the seas. Because if part of the CO2 is absorbed by plants and trees, about a third is absorbed by the Ocean. "The Ocean is both a carbon pump, because it absorbs 25 to 30% of the carbon dioxide (CO2) emissions we produce, and a planetary air conditioner because it also absorbs the heat produced by greenhouse gases", explains Pierre Canet, head of the climate program at WWF. "The rate of warming has increased as global warming has accelerated, reaching the equivalent of three to six Hiroshima bombs per second in recent decades", scientist Dana Nuccitelli told The Guardian.
The Ocean is acidifying
The average pH of the Ocean is normally around 8.25: this level allows an optimal development of marine life as we know it today.
But the Ocean has become 26% more acidic since the beginning of the industrial revolution, and is now around 8.14, reducing the pH of the water.
CO2, absorbed by the Ocean, is the main responsible, while the absorption of nitrogen and sulfur compounds contributes to the acidification but remains less significant.
The Ocean rises
The increase in the heat content of the oceans contributes 30-40% of the global average sea level rise caused by the thermal expansion of seawater (the volume is increasing).
During the last deglaciation, which began 21,000 years ago, the water level rose from 120 to 130 meters, before equilibrating 6,000 years ago. Such changes can only be explained by natural variations. On the other hand, since the beginning of the 20th century, sea levels have risen by about 20 cm, according to the World Meteorological Organization (WMO), mainly due to the thermal expansion of the Ocean and the melting of glaciers and polar ice caps.
Without reducing our GHG emissions, the IPCC (2019 report) estimates that the sea level could rise by 1.1m by 2100*. "Our greenhouse gas emissions have a footprint that stretches from the high mountains to the ocean floor," explains Valérie Masson-Delmotte, paleoclimatologist at the French Atomic Energy Commission (CEA), and IPCC vice-president. The most alarmist forecasts predict a rise in sea level to 2.4 m by the end of the century.
This sea level rise will gradually redefine coastlines. According to the International Union for the Conservation of Nature (IUCN), more than 60% of the world's population lives in coastal areas. 3.5 billion people live less than 150 kilometers from the shore. According to the IPCC, more than one billion people will live in low-lying coastal areas that are particularly vulnerable to flooding or other extreme weather events by the middle of the century.
*Maximum increase estimated by the IPCC, with high emissions, compared to the period 1986 - 2005.
The Ocean is polluted
We too often forget that the Ocean is not essentially composed of water. Incommensurable quantities of ecosystems live there, including microplankton, essential to life.
Marine pollution, resulting essentially from terrestrial resources through the use of fossil fuels, is reaching alarming levels. In 2019, maritime transport was responsible for 90% of the world's merchandise trade (i.e. 940 million tons of CO2, equivalent to 2.5% of global greenhouse gas emissions). This sector could account for 17% of global GHG emissions by 2050.
As for plastics, it represents one of the other major scourges of the century. 300 million tons are produced each year. 20 tons are poured into the world's waters every minute. Patrick Fabre, coordinator at The SeaCleaners, estimates: "2 pieces of plastic for every 5 fish, such is the frightening ratio in the world's seas today. In 2050, it will be 1 piece of plastic for 1 fish".
A part of the plastic (macroplastic) sinks, it gets heavier and settles little by little forming a layer at the bottom of the water. Recovering these plastics is like extracting the life that has accumulated in reef ecosystems and is a chimera. Another part, the majority, is transformed into microparticles and becomes microplastic, barely visible. If collecting visible waste and recycling plastic is necessary, it is only a tiny bandage on our mistakes and certainly not a solution. The tap must be turned off.
The Ocean is deafening
As for noise pollution, it is a disaster of which we are not aware because our human capacities do not allow us to hear it. It travels very long distances and affects marine animals and organisms that depend on sound for orientation, communication and food. The balance of the Ocean depends on sounds. "The oceans will die because of noise. The entire food chain is affected in all the seas of the world," explains Michel André, a biotechnology engineer, bioacoustician, founder and director of the Bioacoustic Applications Laboratory of the Polytechnic University of Catalonia. Sound is their only way of communicating and exchanging information, since light does not penetrate. Sound is life. Polluting these channels of communication is tantamount to condemning marine life to irremissible imbalances.
The Ocean is losing biomass
Global warming obviously has an impact on the oxygenation of the oceans: the solubility of oxygen decreases with the increase in water temperature: the warmer the water, the less oxygen there is. The consequences are the asphyxiation of marine biodiversity and the limitation of its habitat.
Phytoplankton, the marine plant micro organism at the base of the food chain, is gradually disappearing (-10% since the beginning of the industrial era). In the carbon cycle, it is responsible for the production of half of the terrestrial oxygen and captures 100 million tons of carbon dioxide per day.
If greenhouse gas emissions were to remain on their current trajectory, the global biomass of marine animals (fish, invertebrates, mammals) would fall by 17% by 2100 (compared to the average for the years 1990-99). This result only takes into account the effects of climate, without considering other factors (notably overfishing), which have a major impact on biodiversity.
The Ocean is the largest living space on the planet. Today, 280,000 species are recorded. But it remains largely unexplored: it could shelter between 500,000 and more than 10 million different species - excluding the microbial world, whose number of species is estimated to be close to ten billion. Alain Renaudin, founder of Biomim'expo, President of NewCorp Conseil, aspires to real awareness "Our interdependence shows us that it is obviously the planet that will save the human species, if the latter recovers in osmosis and harmony with the whole living ecosystem that surrounds it ".
Humanity must evolve, without compromise.
Towards another future, powered by nature.
Alexandra Corsi Chopin