Don't be so predictable

For decades, Perito Moreno looked unusually stable
because the valley narrowed near its front
and the lake floor rose beneath it.

That shape braced held the glacier from below and from the sides.
A shallow underwater barrier kept colder water trapped near the front.

Those built-in advantages delayed retreat,
but they could not protect the glacier forever
once the ice itself became thinner.

Now: a very delayed response,
slowly but surely detaching
from this physical pinning point.

Thinner ice floats more easily in deep water —
buoyancy, the upward push from surrounding water,
starts opening cracks.

Each loss exposes even more vulnerable already-committed ice to the lake.
Soon, that cycle can feed on itself.

The crack and crash people came for. The louder collapse the sign they missed.