For our cover feature, chief multimedia editor Jeffery DelViscio spent a month in the harsh, desolate and otherworldly icescape of Greenland, where researchers were trying to answer a seemingly simple question with global repercussions: Is the Greenland ice sheet more vulnerable to climate change than anyone knew? To find the answer, engineers and scientists drilled underneath a flowing ice tongue called the Northeast Greenland Ice Stream (NEGIS). If the entire Greenland ice sheet melted, a good portion of the resulting flood would drain through the NEGIS into the ocean, potentially raising global sea levels by 24 feet. By drilling through the bottom of the ice and grabbing a core of the bedrock below, the team could glimpse the place before it was covered in ice. Knowing what temperature supported such an ice-free past would tell us what conditions would be needed to do the same today. One of the researchers who has been studying the bedrock for years is worried: “I have, for the first time ever in my career, datasets that take my sleep away at night,” he told DelViscio.