In the age of GPS and Google Earth, it often feels as though every corner of our home planet has been mapped. At the very least, you think a satellite or two might notice a 450-mile-long canyon—twice the length of the Grand Canyon—poking out the northern end of Greenland.
But they didn't.
Last week scientists at the University of Bristol in the UK announced the discovery of this so-called "mega-canyon,"
which remained hidden from human eyes because it's underneath a 2-mile-thick slab of ice. The majority of Greenland's surface is covered by glaciers and ice sheets, which makes this semi-autonomous island of great interest to scientists studying climate change. The Bristol team set out to map the topology of Greenland's ice sheet and the bedrock underneath it, with the goal of monitoring the ice thickness as global temperatures continue to rise. Over the span of a few weeks they began to notice a long, continuous land feature underneath the ice.This week on the podcast,
I talk to Jonathan Bamber, the lead author on the paper announcing the discovery of the canyon.
The discovery of the mega-canyon was made possible with radar: a simple technique that bounces radio waves off of solid objects and surfaces. By measuring how long it takes the radio wave to bounce off an object and return to the source, it's possible to determine the speed of the object or it's distance. Ice is highly transparent to radio waves, making radar an ideal instrument to measure ice thickness (although, as the lead author on the new paper explains in the podcast, making sense of the radar data is still difficult).
Listen to this week's podcast to hear more about what role this mega-canyon plays in the life of Greenland's ice sheet. You can also check out this NASA video
about the discovery, with some nice graphics.