The results of this study provide an integrated archive of the terrestrial climate over a period of 5 million years, which is a valuable basis for future climate models.
An international team of researchers has discovered an 80-meter-thick sedimentary record in the Sarian Canyon in Kazakhstan. Documents the relationship of climate change between land, atmosphere and sea over the past 5 million years.
This discovered sedimentary record is the first reliable evidence of a location of long-term interactions between the major climatic systems of the Eurasian continent, provided by alternating layers of dust and soil that are preserved as sediments in the Sarian Canyon, which helped researchers verify hypothesis that new water flows into the Arctic Ocean.
Between climatic and land systems
The landscapes of Eurasia seem to have made a significant contribution to the land, atmosphere, and ocean water cycle over the past 5 million years.
The researchers selected the location of the study in Central Asia, as far inland as possible from the sea, and they examined the sedimentary log with a thickness of 80 m and confirmed that the soil samples were taken at different altitudes.
They then measured the relative concentrations of isotopes within the soil carbonates, and redesigned the change of soil moisture over time, dating with uranium, and their accumulation rates leading to soil carbonates and sedimentation.
The analyzed soil samples revealed an area characterized by increased drought over the past 5 million years, and the researchers found that soil moisture was present in the early Pliocene.
Then the drought began, but its drying process was not normal in its transition, but rather variable due to short-term climatic fluctuations, which may be mainly due to the contact between the westerly winds in the middle latitudes and the high pressure system in Siberia.
The Pliocene epoch refers to the last geological period in which the concentration of carbon dioxide in the atmosphere was the same as it is today, at an estimated 400 parts per million, and this period lasted from 5 to 2.6 million years.
Siberian West Wind
The research conducted in the Saren Canyon helped scientists on the long-term relationship between the Siberian mountains and the rainy westerly winds.
The team found that the aquatic climate of the Charien Canyon reflects the grasslands of the north, where many large Siberian rivers flow, affected by the movement of high and western air masses. Thus the activity of the Siberian River in the north may be a major cause of changes in soil moisture at the Charian Canyon site.
The results of this study provide an integrated archive of the landscape climate over the past 5 million years, which is a valuable basis for future climate models.