La salinité des océans influence le climat, aujourd'hui comme dans le passé de la Terre. © peangdao, Adobe Stock

Ocean salt could have played a role in Earth’s habitability

formationambiance It has a direct effect on climateNow, that’s obvious. Several paleoclimate studies have also highlighted the main influence of atmospheric formation on the evolution of Earth’s climate, since the origins of the Earth’s structure…”data-image=” midioriginal/8/4/f/84ff7edce5_123534_terre-apollo8.jpg “data-url =” / ” data-more = “Read more” >a land. However, the formation of the oceans played an equally important, even decisive role in maintaining favorable climatic conditions for the emergence of life at the beginning of the history of our planet. The chemical exchanges between the ocean and the atmosphere are in fact very intense and make it possible to regulate certain processes, in particular at the level of global warming, whose connection with the natural phenomenon of … “data-image = “https://cdn.futura-” data-url = “ -effect-5381 / “data-more=”read more”>greenhouse gases. In this context, the amount of salt in the oceans will be a factor that should not be ignored.

The salinity of the oceans affects the climate

Ocean salinity and climate are two interrelated parameters. If it is currently an issue The effect of climate on salinity due to global warming and the evaporation it causes, and the reverse is also true: salinity is one of…”data-image=” midioriginal/1/e/6/1e63d7d2a5_50034707_campagne-mesure-salinite- captain-robert-pawlowski-noaa.jpg “data-url=” “data-more=”read more”>salinity The oceans have the ability to influence the climate. This is proven by a new study published in the journal Geophysical Research Letters.

The oceans have the ability to store gases in dissolved form. This is especially the case for CO2 We talk a lot about now. However, the solubility of gases in water is closely dependent on the concentration of monatomic and polyatomic ions, cations and anions.
Ions can be monatomic, if they consist of only one type of atom, or polyatomic…”data-image=” / 3/2d3b08d8ec_100849_ion-definition.jpg “data-url =” “data-more =”read more”>ions dissolved in the oceans. Knowing that the salinity of the oceans is determined by the concentration of ions sodium (not available+) and chloride (Cl), the solubility of gases appears to decrease with increasing salinity: the salty ocean will therefore be less captivating greenhouse gasesthat will remain in the atmosphere.

The multiple effects of salt

But the effect of salt does not stop there. Salinity also directly affects the density of the water (salt water is denser than fresh water), affecting the ocean circulation circuits, thus altering the temperature exchange between the water and the ocean.airespecially at the higher level note that one can imagine… “data-image =” .jpg ” data-url = “” data-more = “Read more”>latitudes. A known effect is that salt also lowers the freezing point of sea water, which prevents the formation of ice on the surface of the oceans. This phenomenon limits sea ​​ice formation : The higher the salinity, the lower the temperature must be reached for ice to begin to form.

All of these effects are closely related, and their combination means that a difference in salinity can have obvious effects on ocean circulation, on heat transfer, physicists call thermoelectric energy. In the international system, it is thus measured in joules (J). The heat corresponds more accurately to the transfer… “data-image =” “data-url =” https : // “data-more =” read more “>the heat Towards high latitudes and sea ice formation. However, even small differences in the ice sheet can lead to significant changes in climate by modifying the reflective surface represented by the ice.

A large number of reasons can lead to differences in the amount of salt in the oceans: variation in water level, difference in external inputs (rivers, etc.) or in the level of cold water (therefore … “data-image = “https:/ /” data-url=” source-10993 / “data-more =” read more “>hydrothermal ventsan increase or decrease in the rate of weathering of continental rocks … All these variables make it easy to imagine that the salinity of the oceans has changed dramatically during the history of the Earth.

A more saline Archene ocean would have resulted in a warmer climate even though the sun was still dimmer

Based on a climate model that takes into account the dynamics of the oceans and atmosphere, the team of American scientists shows that the saltier the oceans, the warmer the climate. The results of the study indicate that increasing the amount of salt from 20 to 50 g/kg in ocean water will lead to a 71% reduction in sea ice. These estimates are valid in the current configuration, but also in the past.

During the Archean Era and its Experimental Limits
The first forms of terrestrial life, prokaryotes, appeared during this period marked by the occurrence…”data-image=” archeen-charlie-meeks.jpg “data-url =” “data-more =”read more”>Archianwhich corresponds to the Earth’s first geological period, scientists have shown that an ocean more saline than the present ocean would have allowed the maintenance of a warm climate, in combination with high levels of greenhouse gases.2 and CH4) Up in the air. This conclusion is important because at this time of Earth’s youth, the Then the sun was less bright (about 20% less than today). Thus, the presence of a highly saline ocean can prevent the Earth from turning into a ball of ice, which in particular ensures favorable conditions for the emergence and development of life.

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