Scientists work from above to learn how Greenland is melting from below


Click to enlargeNASA

❝ If the climate keeps warming the way it has, Greenland may finally live up to its name…The island’s glacier-crusted surface is melting, and a lot of this is from balmier atmospheric temperatures. But as the saying goes, that’s just the tip of the iceberg. The oceans are becoming more tepid as well, and that warmer water is causing the glaciers to thaw from below.

❝ Scientists have good measurements of how much ice melts due to warmer air. And now, thanks in part to torpedo-like probes, they are getting better data on the ice being lapped away by sea water. Those submarines are part of NASA’s Oceans Melting Greenland campaign — OMG, for short. And that’s a fairly accurate acronym, because…those glaciers are melting fast…

❝ Greenland’s glacier-gouged coastline provides the deep, warm water a path to the inland ice. Ancient ice sheets carved subsurface fjords and canyons, many of which reach down to the same level as the Atlantic-Arctic currents at the continental shelf. Problem is, “the seafloor around Greenland’s coast isn’t very well known,” says Josh Willis, a climate scientist at NASA’s Jet Propulsion Laboratory and the project lead for OMG. “The location and depths of these underwater fjords and canyons have just been poorly mapped out…”

Willis and his crew have spent the past five weeks flying over Greenland’s coastline, dropping torpedo-shaped probes into the underwater fjords. These units are called…AXCTDS, or Airborne Expendable Conductivity, Temperature and Depth Sensors…

❝ Mission OMG…spans five years and will look for ocean-caused changes to Greenland’s ice sheet. This spring, the team measured glacier height with aircraft radar, comparing past and future data to ascertain which glaciers are vanishing the fastest. The subsurface torpedo work took place this fall, when Arctic sea ice was at its minimum. It was the first time underwater probes had collected data on Greenland’s continental shelf depth, salinity and temperature.

Ultimately, the group wants to know how much of Greenland’s melting is because of air temperature, and how much is caused by water. Koppes, who has worked with the OMG team, believes air temperature and ocean water will play a 50/50 role in glacial melting.

❝ OMG will need time to analyze the data and confirm, but so far they’ve encountered some surprises. “The amount of warm water was bigger than expected, and we saw it in more places than expected,” continues Willis. “Almost everywhere along the shelf where the water was deep enough, we found Atlantic water interacting with the glaciers.”…

And the stakes are high. The deep current warming turns Greenland’s 27,000 miles of coastline — a distance greater than the Earth’s circumference at the equator — into a melt factory. The island’s interior is three times the size of Texas, and holds enough frozen water to raise global sea levels by 20 feet. More than enough to drown the Maldives, Venice, and New Orleans.

RTFA for detail about how research is proceeding, understanding all the processes contributing to the increased melt.

Pic of the Day

In this photo taken from the International Space Station, the European Space Agency’s Automated Transfer Vehicle-3 (ATV-3) is seen on approach for docking. The unmanned cargo spacecraft docked to the space station at 6:31 p.m. EDT on March 28, 2012.

The ATV-3 delivered 220 pounds of oxygen, 628 pounds of water, 4.5 tons of propellant and nearly 2.5 tons of dry cargo. Among other items, the station crew received experiment hardware, spare parts, food and clothing.

The six-member Expedition 30 crew adjusted its sleep schedule to accommodate the ATV-3 docking. The crew stayed up late to monitor the approach and docking.

Those lights below are cities on Earth. How cool is that?