Greenland Icemelt

The rivers and streams that carry glacial meltwater across Greenland’s ice sheet are a beautiful shade of blue, but the water moves so fast and drains so unpredictably into moulins or sinkholes that researchers needed to use a range of high-tech instruments to get their measurements. (UCLA/Laurence C. Smith)

Meltwater drains from Greenland’s ice sheet at such a fast rate that researchers couldn’t risk entering the water to get readings so they used a remote-controlled drone boat. (UCLA/ Laurence C. Smith)

Researchers measured how fast water was flowing through rivers using an Acoustic Doppler Current Profiler. (UCLA/Laurence C. Smith)

To calculate river flow, researchers used autonomous GPS beacons, which drift down the river broadcasting its location and velocity to communications satellites. (UCLA/ Laurence C. Smith)

UCLA geography graduate student Lincoln Pitcher (left) and UCLA geography professor Laurence C. Smith overlook the mighty Isortoq River, where meltwater leaves the Greenland ice sheet to flow to the ocean seen in the distance. (UCLA/Laurence C. Smith)

Conditions were so risky on the ground that researchers surveyed the ice sheet from the safety of a helicopter. (UCLA/Laurence C. Smith)

The UCLA-led team mapped 523 supraglacial rivers, which flow across the top of glaciers. These drained meltwater from a 5,000 square kilometer area of southwest Greenland after an extreme melt event in 2012. (UCLA/Laurence C. Smith)

When snow and ice melt during the summer months, waterways like this one form an intricate drainage system that captures virtually all surface runoff. (UCLA/Laurence C. Smith)

Greenland’s supraglacial rivers are large and swift. Note researchers on right for scale! (UCLA/Laurence C. Smith)

The UCLA-led study finds that a vast network of previously little-understood rivers and streams that flow on the ice sheet into the ocean could be a major factor contributing to rising sea levels. (UCLA/Laurence C. Smith)

All of the 523 supraglacial rivers abruptly end in moulins, such as the one seen near the top of this photo. (UCLA/Laurence C. Smith)

Meltwater formed on the surface of the Greenland ice sheet rushes into supraglacial rivers that then fall into moulins or sinkholes such as the one shown here. (UCLA/Laurence C. Smith)

Researchers moved around the 5,000 square kilometer research area by helicopter. (UCLA/Laurence C. Smith)

Researchers were ferried by helicopter since conditions on the ground were so dangerous. (UCLA/ Laurence C. Smith)