A cross sits on the side of the road as fog covers homes in Kulusuk, Greenland, early Thursday, Aug. 15, 2019. Greenland has been melting faster in the last decade and this summer, it has seen two of the biggest melts on record since 2012. (AP Photo/Felipe Dana) 
An iceberg floats near a cemetery in Kulusuk, Greenland, early Thursday, Aug. 15, 2019. Greenland has been melting faster in the last decade and this summer, it has seen two of the biggest melts on record since 2012. (AP Photo/Felipe Dana) 
Dogs sit outside a home in Kulusuk, Greenland, early Thursday, Aug. 15, 2019. Greenland has been melting faster in the last decade and this summer, it has seen two of the biggest melts on record since 2012. (AP Photo/Felipe Dana) 
In this photo taken on Wednesday, Aug. 14, 2019, icebergs are photographed from the window of an airplane carrying NASA Scientists as they fly on a mission to track melting ice in eastern Greenland. Greenland has been melting faster in the last decade and this summer, it has seen two of the biggest melts on record since 2012. (AP Photo/Mstyslav Chernov) 
In this photo taken on Wednesday, Aug. 14, 2019, NASA scientist Josh Willis looks out of the window after dropping a probe from a plane as they fly above the Kangerlussuaq Glacier, eastern Greenland. Greenland has been melting faster in the last decade and this summer, it has seen two of the biggest melts on record since 2012. (AP Photo/Mstyslav Chernov) 
In this photo taken on Wednesday, Aug. 14, 2019, pilots Andy Ferguson, left, and Don Watrous, fly a plane carrying NASA scientists on a mission to track melting ice in eastern Greenland. Greenland has been melting faster in the last decade and this summer, it has seen two of the biggest melts on record since 2012. (AP Photo/Mstyslav Chernov)
ABOARD A NASA RESEARCH PLANE | NASA scientists are crisscrossing Greenland on a mission to track melting ice.
Greenland has been melting faster in the last decade and this summer, it has seen two of the biggest melts on record since 2012.
Global warming is the chief culprit, but scientists want to know how this is happening. Both warmer air and warmer water are eating away at Greenland, causing it to lose billions of tons of ice daily in the summer.
A team of scientists and engineers aboard a research plane this week are dropping probes into the ice to help figure out which is the bigger cause.
If water is playing a bigger role than scientists had thought, that could mean seas will be rising faster than expected.