[Music, low plane engine sound] Narrator: Below thousands of meters of ice
ice in Antarctica, lie hundreds of meltwater lakes
where the Antarctic Ice Sheet meets the continent’s bedrock.
Until pretty recently we thought that these lakes sat quietly,
isolated in pockets under the ice.
But in 2007 laser measurements of the ice surface
from NASA’s ICESat satellite were used to infer what was happening far below.
And a much more interesting picture was revealed.
By watching local areas of the surface
of the massive ice sheet rise and fall
due to fluctuations in the lake water levels below,
we learned that vast hydrologic systems like rivers connect many of these lakes,
and that some actively fill and drain all the time.
Thanks to the more advanced laser technology
on NASA’s ICESat-2 satellite, in a region very near
near a pair of larger lakes measured in 2007,
two more of these lakes have just been found.
A new study shows they are currently experiencing a draining period.
The finding also gives us the most detailed picture yet
of how the boundaries of lakes can change over time.
Areas seen here in blue
show that the surface of the ice is getting lower,
which indicates that the lakes below are draining.
Understanding how much water is flowing under the ice sheet, and how quickly
quickly it can drain to the sea, helps give us a better picture
of not only how quickly the Antarctic Ice Sheet will change
due to a warming climate, but also how Antarctic melt will affect
both global ocean currents and sea level rise.
[music fades]