Researchers find out how Arctic ice affects Siberia's climate

Researchers find out how Arctic ice affects Siberia's climate
Researchers find out how Arctic ice affects Siberia's climate
Anonim

In recent years, the volume of summer sea ice in the Arctic Ocean has been decreasing. This could have an impact on “permafrost” and the release of large carbon stores from it. This conclusion was reached by an international team of scientists from the Institute of the Earth's Crust SB RAS, caving club "Arabica", Geological Survey of Israel, Oxford University and Northumberland University of Great Britain. Researchers analyzed data for one and a half million years obtained from the study of stalagmites in the caves of Siberia. The results of the work were published in the journal Nature.

The caves are a unique recorder of paleoclimatic changes. Stalagmites, stalactites, drip forms and other types of speleothem can form when the rocks above the cave are in a thawed state, and water in liquid form freely circulates in the soil and rocks.

The new study combines many years of challenging fieldwork with the development at Oxford University of new approaches to studying stalagmites.

“We studied the Siberian caves Lenskaya Ledyanaya and Botovskaya, located in different geocryological zones. Stalagmites in these caves grew in favorable conditions, when moisture and heat were present in the cave. Now observed caves in areas of continuous distribution of permafrost rocks are waterless and speleothems do not grow in them. The presence of ancient speleothems in these caves indicates warm periods in the past, and clearly pronounced breaks in their growth are a sign of the time of formation of permafrost,”says one of the authors of the study, Deputy Director for Scientific Work of IZK SB RAS, Candidate of Geological and Mineralogical Sciences Alexander Matveevich Kononov …

Samples of stalagmites have been dated by uranium-thorium and uranium-lead methods based on the natural decay of the isotopes of uranium, thorium and lead. This method, developed at Oxford University, made it possible to determine the periods of melting of permafrost Siberian rocks over the past one and a half million years.

“The stalagmites of the Lena Ice Cave (Yakutia) are the most ancient. Their growth was periodically interrupted in the time interval from 1,500,000 to 400,000 years. The southern caves have speleothems with periods of growth up to the present time. Studies have shown that in the area of the Lena Ice Cave at the turn of 400 thousand years, a stratum of permafrost was formed and remained stable to the present, despite warmer periods. This became possible due to the formation of long-term sea ice in the Arctic, which led to climate change and cooling of the depths of Siberia,”explains Alexander Kononov.

Permafrost is widespread in a quarter of the Northern Hemisphere and stores large amounts of carbon. Modern scientific research cannot yet accurately predict the rate of melting of permafrost rocks, nor can they estimate the amount of carbon that can be released into the atmosphere if they melt. The reduction in the volume of perennial Arctic ice, which is happening today, can significantly change climatic processes. In turn, this will further accelerate the melting of permafrost, which scientists are currently observing instrumentally.

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