The voluminous noise the bubbles make is not the noise of them bursting in water but the noise of them resuming their natural shapes when released into water after having been frozen misshapen from ancient times. For the first time, this bubbling symphony is recorded by researchers working in the fjords of Alaska’s Icy Bay.
Alaska’s Icy Bay Glaciers
As explained by lead author Erin Christine Pettit, the glazierized fjords of Alaska’s Icy Bay illustrate the dynamic and changing environment at the boundary between ocean waters and frozen glaciers. This ice-ocean boundary environment is sensitive to the forces of both glacier flow (or retreat) and ocean water circulation. Results from Icy Bay were compared to other fjords in Alaska and Antarctica.
The popping from bubble formation in the water column from glacial melt, which is otherwise called ambient noise, gives a means of examining the change occurring and the processes driving the change because ambient noise can ebb and flow in response to glacier or ocean flow or circulation. It is also hypothesized that the high levels of ambient noise affects and alters the behavior of ocean mammals, especially the seals and killer whales in Alaskan waters.
Implications of Ambient Noise
It is projected by the team of researchers that the dynamic nature of the ambient noise from bubble formation, which is directly tied to the rate at which a glacier is melting, can be used to measure the rate of ongoing glacier melt and future melt rates might be predicted. The underwater ambient noise would give a direct indicator of glacial melt in any location.
Since ambient noise appears to alter the behavior of ocean mammals, it is also hoped that ambient noise can help explain dwindling populations of Alaskan seals in fjords where glaciers have retreated so far as to be out of fjord waters. It is suggested that there may be some connection between the glacier melt dynamic and the ability of seals to evade the killer whale, although this may only partially explain the correlation between seal populations and their ability to evade predators.
Geophysical Research Letters
“Unusually Loud Ambient Noise in Tidewater Glacier Fjords: A Signal of Ice Melt” contributed by the research team of Erin Christine Pettit, Kevin Michael Lee, Joel Palmer Brann, Jeffrey Aaron Nystuen, Preston Scot Wilson and Shad O’Neel was reported online in Geophysical Research Letters.
