(ORDO NEWS) — During ice ages, sea levels drop as the resulting glaciers retain water. So far, computer models have failed to match sea level height with glacier thickness.
Inconsistencies between the water mass and the mass of glaciers during the ice and interglacial periods led to the “problem of missing ice”. Now scientists have used a new measurement method and were able to solve this problem.
During the transition from ice ages to interglacial periods, the glaciers of Greenland, North America and Europe gradually increase and decrease over tens of thousands of years. The more water turns into ice, the less it remains in the oceans and the lower the sea level.
Climatologists today are studying how much glaciers may melt in the coming centuries due to anthropogenic climate change, and how much sea level will rise as a result. For this, scientists analyze the past. If they can understand how ice grew and melted during the past ice ages and interglacial periods, they can draw valuable conclusions about the consequences of global warming.
The “missing ice problem” has remained unresolved for many years. She describes the inconsistency of two different scientific approaches that sought to correlate sea level height and glacier thickness at the peak of the last ice age – about 20,000 years ago. The authors of the new work found a solution to this problem. They took into account many geological conditions in glacial regions – they estimated the angle of inclination of the glacier surface to the horizon, the direction of flow of melt water from them, as well as the resistance of rocks and sedimentary rocks at the base of the glacier to the flow of flowing water.
By analyzing all these parameters, the authors were able to correctly compare sea level and glacier mass. According to the authors’ calculations, the sea level 20,000 years ago was about 116 meters lower than today. These data show that no “missing ice” exists and all the data in this calculation converge. Errors in previous calculations, according to scientists, may be associated with the inaccuracy of the isotope model – earlier scientists showed that at intervals of 20,000 years and earlier, it does not allow to calculate the mass of water and glaciers well enough.
An article about the discovery was published in the journal Nature Communications.
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