Greenland has been free of ice at least once in the past 1.1 million years. Here’s what researchers have to say about Andrew Crest of the University of Vermont In the magazine “PNAS”. This could be an indication that the Greenland ice sheet is more sensitive to warming than previously thought. If it melts completely today, the sea level will rise by about six meters worldwide, inundating coastal areas and cities.
The team examined a core of pits recovered in northwest Greenland in 1966. The core contains a cross-section of ice sheets, 1.4 kilometers thick at this point, plus a few meters of ground beneath it. Scientists have discovered various plant remains, including cranberry branches as well as leaves and stems of various mosses. They are the remnants of a tundra-like ecosystem that has been around for a long time.
Clear isotopes
Scientists have determined the ratio of isotopes of two elements in sediments: 26Al, a form of aluminum, and 10Be, a variety of beryllium. Both are caused by cosmic radiation on the surface of rocks and then decay at different speeds. Their relationship on Earth says something about the last time it was revealed under the open sky. In northwestern Greenland, according to measurements, this does not appear to have been more than 1.1 million years ago. At that time the vegetation could have grown, and its effects can be traced today.
Oxygen isotope analysis 18Oh and 16Supports O the thesis additionally. The two isotopes differ in their masses, and thus their ratios provide information about past evaporation rates and isotope separations – for example, rain of water molecules, which are heavier. 18O listed, tend to be more. The 18The/16The O ratio in the core of craters from northwest Greenland indicates that the precipitation that once inundated the sediments did not fall where the ice surface is today, but at a much lower altitude – and it has decreased at higher temperatures than it currently does in Greenland rule. According to the researchers, this also indicates that the ice sheet was not present at that time.
Drill cores from within Greenland show that the sediment layer under the ice has similar isotope ratios as in the northwest of the island, as Jesus and his team wrote. Presumably, glaciers in both regions – and possibly other parts of the country – disappeared at the same time. According to scientists, this probably happened during a warm period of about 30,000 years ago a million years ago. at that time Sea level has reached a record levelThe temperature rose in Northeast Siberia.
If the researchers’ conclusions are correct, then the Greenland ice sheet is more sensitive to climate change than previously thought. In fact, there are growing signs that ice loss on the island is increasing rapidly.
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