Scientists are becoming clam whisperers to better predict when our planet's climate will tip over into danger.
clams are exceptional natural historians, even though a tight-lipped bivalve may sound odd to researchers.
Growth bands on shells hold important information about the environment and how it has changed over time.
These intricate passages can be read by scientists centuries after they were written down.
The ancestors of clams have been laying down passages in the mineral calcite for hundreds of millions of years.
The ancient archives are warning. A new reading of three bivalve records has shown a potentially dangerous tipping point in Earth's climate.
The findings show that a feedback loop wearing away at the stability of a climate system in the North Atlantic Ocean caused a shift in our global climate some eight centuries ago.
The 'Little Ice Age' began in the 13th century in the North Atlantic and ended when heating reverses the natural trend.
According to the shells of clams, the mini-ice age might have been caused by a sudden change in the ocean current patterns in the North Atlantic.
Sea ice in the North Atlantic is melting at a rate that may have weakened the ocean currents.
This could have led to a reduction in how much heat the currents carried towards the pole.
There was going to be snow and ice on the stage.
The North Atlantic may be approaching another worrisome tipping point as we head in the opposite direction.
A subpolar gyre tipping point might again lead to rapid and long- lasting regional climate change if rapid loss of sea-ice, accelerated melting of the Greenland ice sheet, and associated export of freshwater into the North Atlantic continues.
clams are a proxy for past climates in the marine setting.
Some of the longest living creatures on the planet are the quahog clams. The oldest animal ever found was a quahog clam that lived to be 509 years old.
Because clams pull oxygen and carbon out of the water to lay down their shells, the chemical composition of their growth lines can show changes in the marine environment.
Researchers have found a consistent pattern in long-lived, deep-sea clams that suggest a weakness in the North Atlantic's subpolar currents.
The first weakening episode took place between 1180 and 1260CE and the second between 1330 and 1380CE after some volcanic eruptions.
In the interval between these episodes, the shell growth and carbon isotopes in the clams suggest that the environment kept pace with the changes. The authors observed a decline in shell growth after 1300CE.
The presence of increased sea ice in the region may have disrupted production and food supply to the sea bed below. The ecosystems never came back to baseline after that.
Its resilience seems to have gone for the worse.
The Little Ice Age may have begun in response to the weakness of the subpolar gyre, according to the evidence presented here.
There is more research that needs to be done to confirm the findings. The collapse of the North Atlantic currents around 1300CE is tied to the Little Ice Age by other studies.
The North Atlantic may be in even more trouble than we thought if the studies are correct.
The study was published in a scientific journal.
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