Antarctic Ice: Bottom’s Up!
Scientists in Antarctica, at the South Pole, made an important discovery recently.
Originally, they thought the ice there had a bottom base and as the snow fell and hardened, it became thicker and thicker. Makes sense, right? But, it turns out that’s not exactly how it happens. It does happen that the top layers get snow which pack and harden, that’s true. But it also turns out that the water under all that ice can also freeze and adds ice layers from the bottom.
If the glacier is about 2 miles thick and frozen solid, how do you think scientists made this discovery? By plane, equipped with special radars, lasers and other sensors that actually see through the glacier and under it … from above! And what they saw amazed them.
Underneath the huge, thick ice sheets is flowing water, rivers, lakes, mountains and volcanoes, miles and miles underneath the ice. There’s a special place in that area that has a huge mountain range all under water and under ice, called the Gamburstev Mountains.
Scientists chose this spot because water acts differently on an angle. If there is little pressure for it to flow with all the other water and it can sit still then it freezes faster. They saw that the highest mountain peak had a 3,609 foot “plume” of ice that had frozen.
So, why is this important? Scientists who saw these findings thought it was “jaw dropping” … and it actually changes history.
In some places it turns out that ice is being created faster from the bottom than the top and this refreezing can account for slightly more than half of the total ice thickness!
This discovery changes the way scientists thought Antarctica was shaped.
But it also changes what they can learn about the past. Each layer of ice tells a story about the past (kind of like rings on a tree). Scientists drill down, take a sample from a layer (usually air bubbles) and study it. Up until now, the thinking was that the farthest down layer was also the oldest, and now that doesn’t seem to be the case. And with the ice from the bottom also melting, flowing around, and refreezing it’s trickier to find the oldest ice and some of it is gone forever once it melts.
Scientists have samples as far back as 800,000 years and right now are looking for a 1.5 million year old piece of ice they can study.