One possibility is that the glacier was holding back a lake of meltwater, and that heavy snowfall in the region two days earlier added enough volume to the lake that the water forced its way out, breaking the glacier and surging into nearby rivers.
Therefore, climate change was directly responsible for the threat that meltwater posed to the city.
When meltwater reacts with minerals eroded by the glaciers, it produces hydrogen gas that microbes can use to generate chemical energy.
Boyd and his team sampled meltwater from glaciers in Iceland and Canada.
Previous research suggested that meltwater from the Greenland and Antarctic ice sheets might also play complicated feedback roles.