These are two crucial glaciers in West Antarctica. They are undergoing the biggest melt in 5000 years. So says a study published in Nature Geoscience. The University of Maine led it.
The glaciers are Thwaites and Pine Island. They extend deep into the heart of the ice sheet. But they are melting too fast. They would cause sea levels to rise as much as 3.4 meters in the next few centuries.
how has the relative sea level changed over the last few thousand years? Shells were collected from several ancient beaches. With radiocarbon dating it was known when the beaches were formed. This traces whether there were changes in the size of the glaciers, during the time covered by those ancient beaches.
where did the samples come from? From Pine Island Bay, rarely visited islands. They collected more than 50 penguin shells and bones for the study. It was learned that the relative sea level in the region fell steadily over the last 5000 years. Glaciers remained relatively stable during that time.
Brenda Hall is an author of the study and a professor at the Climate Change Institute (USA). She says in a statement, “The recorded rate of relative sea level fall is nearly five times slower than it is today. The reason is the recent rapid loss of ice in the region.”
Looking back in time allows us to understand how these massive glaciers react to changes in climate.
“Our results,” they say, “show that. The climate was warmer before, but the glaciers were not smaller than today. The biggest melt in 5000 years is happening now. It is a dramatic loss of ice, unprecedented in the recent geological past. We urgently need to understand more about these glaciers to determine whether their current retreat could be reversed. Under what conditions might this happen? This is crucial if we are to effectively plan for future sea level rise.”