The Gulf Stream is weakening every year. The study, published in the journal End of February, found that the currents, which cross the Atlantic and allow Europe to benefit from milder winters in winter, are currently at a record low of less than a million. Natural Earth Science.
To this end, Irish, English and German researchers studied a component of the Gulf Stream: the meridian cycle of the Atlantic reverse (AMOC). “This system works like a giant treadmill, Stephen Rahmstorf, co-author of the study, explains. The hot, salt water moves from south to north and cools there, becoming more dense. When it is sufficient, the water flows into the deep ocean layers and returns south. “ In total, it transfers about 20 million cubic meters of water per second to AMOC, or almost a hundred times the flow of the Amazon River.
AMOC began measuring directly only in 2004. Before that, there was very little data. To accurately analyze this phenomenon, researchers had to observe indirect indicators. “For example, we looked at the size of the grain in the oceanic cores, The first author of the study, Levke Caesar, explains. This is because fast currents can carry large grains. We also looked at the composition of species of corals because they are distributed according to different water temperatures, and finally compile historical data, for example from record books. “ Together, these indicators draw a picture of how the cycle has changed over the years.
Algorithm of currents disturbed by warming
And the observation is clear: “We found that the sea cycle was stable until the end of the 19th century.e Century, Explicit Stephen Rahmstorf. At the end of the Little Ice Age in 1850, and before the second fall of the mid-20th century, sea currents began to recede.e Century. “ According to all the data studied, the sea level has dropped by about 15% in the last seventy years.
This phenomenon has worried researchers for many years. Climate models in response to global warming AMOC recession has long been predicted. According to several studies, this may be the main reason for the weakening. Global warming actually disrupts the mechanism of currents. Increased precipitation and melting of the Greenland ice add fresh water to the ocean surface; For its part, global warming is increasing the surface temperature of the oceans. This reduces salinity, and therefore the density of the water, which has a lower tendency to dive deeper. “It simply came to our notice then. Didier Swingedov, a CNRS researcher who did not participate in the work, explains. This hypothesis of climate change exists, but natural cycles may also work. ”
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