Scientists at the Alfred Wegener Institute for Polar and Marine Research in Germany have questioned the established scientific model that correlates sea level with the volume of glaciers in the past, and solved the long-term missing ice problem in the last ice age. The results of the study, published in the leading scientific journal Nature Communications, will help to accurately reconstruct the climate in ancient times and predict it in the future.
In the transition from glacial (ice age) to interglacial glaciers in Greenland, North America and Europe begin to decrease. The less water is stored in glaciers, the more it is in the oceans and the higher the sea level. However, until now it was not known how to reconstruct the thickness of the glaciers at that time from sea level data. The problem was that the two different scientific approaches that were used to reconcile the sea level on Earth and the thickness of the glaciers 20 thousand years ago gave incompatible results.
One approach is based on the analysis of sediment samples from the seabed in the tropics. The samples contained the remains of corals that typically inhabit well-lit waters near the sea surface. According to the results of the analysis, 20 thousand years ago, the sea level was about 130 meters lower than today. However, other models say that this requires an additional mass of water to be frozen, which is twice the mass of the Greenland ice sheet. According to the available data on the volume of glaciers, the sea level should have actually been 102-122 meters lower.
According to a new study, sea level was 116 meters lower than today. Scientists have reconstructed the ice sheet over the past 80,000 years, taking into account factors such as the steepness of the ice sheet, the direction of the flow of glaciers, the resistance of rocks to the flow of the glacier, and the pressure of the ice layer on the earth’s crust. At the same time, the need for additional mass was avoided, which solved the problem of disappeared ice.
An approach based on measuring oxygen isotopes is usually used to estimate the mass of glaciers. According to theory, the light isotope O-16 evaporates, while O-18 remains in the water. During the Ice Age, the volume of water in the oceans decreases and the concentration of O-18 increases. However, the results of German scientists demonstrate that this connection can be much more complex than previously thought