Heavy ice loss in West Antarctica has weakened it mantle underneath, allowing the stronger East Antarctica mantle to push it around, according to Ohio State University researchers. The discovery was made after recording GPS measurements, which clearly showed that the West Antarctic bedrock is being pushed at an alarming rate of half an inch per year.
Though the observation didn't come as a surprise to lead researcher Terry Wilson, she found the half inch movement is quite a lot compared to other areas of the planet.
Wilson and her team of researchers have been using GPS measurements to study ice movements and loss since the early 1990s. What surprised Wilson most was that the movement was taking place in the direction of greatest ice loss.
From computer models, we knew that the bedrock should rebound as the weight of ice on top of it goes away, Wilson said. But the rock should spread out from the site where the ice used to be. Instead, we see movement toward places where there was the most ice loss.
Using seismic sensors, researchers were able to determine that the bedrock of east and west Antarctica are very different from each other. The former contains harder and colder rocks while the latter is made from softer, warmer rocks.
Stephanie Konfal, a research associate with POLENET compared the whole tilting process to that of a honey comb with warm and cold spots, making regions soft and hard respectively.
If you press down on the surface of the honey with a spoon, the honey will move away from the spoon, but the movement won't be uniform, she said. The hard spots will push into the soft spots. And when you take the spoon away, the soft honey won't uniformly flow back up to fill the void, because the hard honey is still pushing on it.
Such extreme differences in bedrocks have not been observed anywhere on Earth where glacial rebounds occur. Researchers of this study said that though they always anticipated Antarctica would be different they never expected this difference to be so huge.
The findings of this study are very important as researchers often use ice sheet movements to measure and predict ice loss.
We're witnessing expected movements being reversed, so we know we really need computer models that can take lateral changes in mantle properties into account,” Wilson concluded.
What chances are there for this movement to increase its rate? Though no proven studies have been conducted on this front, it is not rocket science to guess that it is very likely that the rate of shifting may increase in the future since past studies have predicted an increase rate of ice loss due to global warming.
Only recently an active volcano was discovered under the Antarctic ice sheet. Researchers say that if this volcano was to erupt, it will increase ice loss rates by a significant amount. What's even more concerning is that the volcano has been discovered only one kilometer beneath West Antarctica, the weaker side of the ice sheet. Amanda Lough of Washington University said that an eruption is very much possible though she cannot put a definite date to it.