The Arctic is fast becoming an important area for climate change research. The harsh and remote region, which is warming four times faster than the rest of the Earth, is changing rapidly.
But studying the region is challenging due to the harsh climate conditions. Now, scientists at the US-based Sandia National Laboratories (SNL) are using an existing fiber optic cable off Oliktok Point on the North Slope of Alaska to study the conditions of the Arctic seafloor up to 20 miles from shore.
According to a news release from SNL, their goal is to determine the seismic structure of miles of Arctic seafloor. Christian Stanciu, project lead, recently presented their latest findings at American Geophysical Union’s Fall Meeting in San Francisco earlier this month. SNL says using an emerging technique, scientists can spot areas of the seafloor where sound travels faster than on the rest of the seafloor, typically because of more ice.
How does the technique work? Permafrost and bouncing laser light shots. To study permafrost on the Arctic seafloor, the researchers used pulses of laser light shot down a submarine telecommunications fiber optic cable buried off the coast of Alaska, running north from Oliktok Point. Tiny imperfections in the cable caused light to bounce back to a sensor system, the news release explains. By capturing this light at two wavelengths, or colors, and comparing them, the researchers could determine the temperature of the cable every yard, said Jennifer Frederick, a computational geoscientist. This technique is called distributed temperature sensing.
The scientists also used the cable to determine temperatures over the stretch of seafloor and monitored temperature changes over seasons. These data, unlike any collected before, were inserted into a computer model to infer the distribution of submarine permafrost, the release explains.
“One of the innovations of this project is that we can now use a single fiber to get acoustic and temperature data,” Stanciu explains in the release. “We developed a new system to remotely collect both types of data using one fiber strand. We’re getting some interesting results.”
By looking at light of a different wavelength the researchers could detect when the cable had been strained by a passing sound wave. This so-called distributed acoustic sensing provided information about the structure of the seafloor to depths of one to three miles, Stanciu said.
SNL has been collecting climate data from northern Alaska for more than 25 years. The current research project started about a year ago, the news release explains.
“The fact that we can monitor the temperature continuously, we can now pick up changes from year-to-year and season-to-season,” Frederick said in the release. “We’re specifically looking for unexplainable warm spots. We think we’ll be able to see areas of seafloor seeps — somewhat like springs coming out of the ground, except on the seafloor. We’re interested in them because they’re carriers of deeper, carbon-rich fluids and are an indication of warming and change.”
A Reuters report earlier this month noted how the Arctic experienced the warmest summer on record this year, contributing to extraordinary wildfires and melting glaciers while threatening the rest of the world with problems including higher sea levels.