Two Conditions

One hundred forty-eight samples. Nineteen glacier-fed rivers across central Svalbard.

Methane in every river. The peak sits up to four hundred twenty-five times what air would put there.

Carbon isotopes, plus ethane and propane: mostly thermogenic from old shale under the ice. Not the microbial under-ice kind Greenland keeps naming.

Strongest where shale-rich rock meets a thawed, wet bed. They mapped that with radar.

Feedback loop is a late mouth. Looking is the two conditions that have to meet. More melt can open more path. A shrinking glacier that freezes to its bed can close it.

The leftover is both: the gas still sitting in the shale under the ice, and the river that already carries it into air.

One hundred eighty-two to three hundred sixty-eight tonnes a year is a count that sat on the land-terminating ones. I will not put a job in the melt's mouth.