The mass system of rotating ocean currents in the North Atlantic behaves extremely strange, perhaps because it approaches a turning point, shows a new analysis of the shell of mollusks.
The northern Atlantic subpolar anthem plays a key role in the transportation of heat to the northern hemisphere, and it is part of a much larger network of ocean currents, called the Atlantic meridional inverted circulation (AMOC). But the new data indicate that underground weights since the 1950s have been losing stability, which means that the circulation of Gira can significantly weaken in the coming decades, researchers report in a study published today (October 3) in the journal. The science of achievementField
The northern Atlantic underground weight is an AMOC limb, but it can independently cross a turning point from a giant current network. The climatic results for Europe, in particular, will be similar to those that will be caused by the AMOC collapseAlthough they can be less intense, because AMOC is much larger, said Alellano Nava. However, “even if the consequences are not as disastrous as for AMOC collapse, the weakening of the underground hydraulic gyra can lead to significant climatic effects,” she warned.
Previous studies show AMOC can collapse in the near future Because its main engine – a cascade of thick water from the surface of the North Atlantic and Arctic Oceans to the sea – fails. This cascade, which was still made of extremely cold and salt water, is diluted with molten water and heats up with increasing global temperatures, which means that the water in some places is no longer quite dense to plunge correctly. (Cold, salty water is denser than warmer, smaller water.)
A similar fate is expected for the northern Atlantic underground weight -GIR, which also relies on sinking surface water to the floor of the ocean. According to Alellano Nava, the cascade of dense water in the Gyre nucleus forces rotating the rotating currents. But the system is also partially due to the wind, so the full collapse is unlikely, she said.
The northern Atlantic underground weight is the AMOC branch, so the AMOC collapse necessarily includes the dramatic weakening of Gyre. Conversely, the weakening of the underground Gyre does not automatically mean that Arelno Nava said Amoc.
“The underground weight can sharply weaken without the collapse of AMOC,” she explained. “This is what happened during the transition to a small ice age, which occurred in the 13th and 14th centuries.”
A small ice age, which lasted from the 1250 to the end of the 1800s, is one of the coldest periods in the northern hemisphere from the end The last ice ageThe average temperature field decreased by about 3.6 degrees on Fahrenheit (2 degrees Celsius), freezing rivers and food throughout Europe and North America in winter, causing agricultural crises and generally throwing a medieval society into chaos A resident of New YorkaThe field, although factors such as volcanic eruptions and a decrease in solar activity contributed to the beginning of a small ice age, the northern Atlantic underground weight. I thought he played the main role In strengthening it.
WITH Climate changeAccording to Alellano Nava, the conditions are very different than in the 13th century, so scientists do not know whether another small ice age is possible. Nevertheless, this illustrates some climatic effects that may appear on our way.
Hipples in mollusks
For a new study by Alellano Nava and her colleagues analyzed the existing sets of data obtained from the shells of two types of mollusks living in the North Atlantic: The Arctic of the Islandak And Glycimer glycamersThe mollusk field record information about the ocean in their sinks as they grow; For example, they absorb various forms of elements such as oxygen, which can give researchers to hints of oceanic processes over time.
“With the help of Clam Records, we have good acquaintances for each of the layers,” said Arellano Nava. “They look like the trees of the rings of the ocean.”
Researchers have collected 25 data sets to build a high resolution picture in the North Atlantic underground Gira over the past 150 years. They found two strong instability signals. The latest continues and suggests that underground weight is approaching a turning point in global warmingWhich supports previous observations and research, said Arellano Nava.
But another signal was complete surprise, she said. Data from mollusks showed that underground weight was unstable for several years in anticipation of the change in the regime in the North Atlantic of the 1920s. This previously described event was characterized by an increase in the currents in Gyre. According to Alellano Nava, instability in the underground hirre probably caused a shift in the 1920s regime, and the terms suggest that the period of instability could reflect the restoration of the underground hydraulic gyra after its slight collapse of the ice age.
“At some point, he had to restore, but this is not what we have complete evidence for, because we did not plunge into these mechanisms,” she said.
Regardless of whether the instability at the beginning of the 20th century was actually a signal that underground weight was returning to its full force, the overlapping between the signal in the mollusks and the change of regime in the North Atlantic of the 1920s shows that the results are reliable, said Arellano Nava.
“If you observe the loss of stability, accompanied by a rapid change, then you are sure that these are early warning signals for sudden changes,” she said.
However, another expert was less convinced. “Data sets are very useful because they are very obsolete and give an idea of climate changes on an annual basis.” David TornallyProfessor of the Ocean and Climate at the University College of London, who did not participate in the study, told Live Science in an email.
But the analysis did not associate the patterns observed in the mollusk data directly with the physical characteristics in the ocean, and did not provide strong support for shift in the underground Gyre operation mode, Tornally said. “I am skeptical of interpretation,” he said.
As for the ongoing destabilization of the northern Atlantic underpolar weight, Alellano Nava said that she and her team switched to a map of potential climatic trajectories that this could unlock.
“We don’t know exactly what a turning point is,” she said. “It can be AMOC, … but we can first observe the underground weakening of the weight, and this definitely bothers.”
