The sheet of ice that covers Greenland
contains enough frozen water to raise oceans by 25 feet
across the globe
As the planet warms, glaciers melt
causing sea levels to rise
But not all of that melt happens at the surface
In the summertime, rivers and pools of meltwater
find their way down through the glacier
to the bed below.
From there, the water runs beneath the glacier
until it reaches the ocean.
Because meltwater contains no salt,
it weighs less than ocean water
and rises up the front of the glacier
in what scientists call a plume.
Around Greenland, oceans are cold and fresh near the surface
and warm and salty at depth
As the plume rises, it draws in the warm, salty water
metling the glacier face from the bottom up.
Eventually, a piece of the glacier breaks off
making an iceberg in a process known as calving.
As the oceans warm,
calving speeds up, causing glaciers to retreat
and flow faster.
Faster glaciers dump more ice into the oceans
and drive sea levels higher across the globe.