Glaciologist Martin Stocker-Waldhuber, from the Austrian Academy of Sciences, explores a natural glacier cavity of the Jamtalferner glacier near Galtuer, Austria, October 15, 2021. Giant ice caves have appeared in glaciers accelerating the melting process faster than expected as warmer air rushes through the ice mass until it collapses. REUTERS/Lisi Niesner

Glaciologist Andrea Fischer, from the Austrian Academy of Sciences, explores a natural glacier cavity of the Jamtalferner glacier near Galtuer, Austria, October 15, 2021. Scientists are venturing inside otherworldly ice caves growing beneath Austria's doomed glaciers to study why they are melting even faster than expected, and understand the fate that will befall glaciers elsewhere if climate change is not halted. REUTERS/Lisi Niesner

Glaciologist Martin Stocker-Waldhuber, from the Austrian Academy of Sciences, explores a natural glacier cavity of the Jamtalferner glacier near Galtuer, Austria, October 15, 2021. The eerie blue caverns beneath them hold clues as to how the ice which built up over millennia and melted over decades collapsed far faster than expected. REUTERS/Lisi Niesner

Glaciologists Andrea Fischer and Martin Stocker-Waldhuber, from the Austrian Academy of Sciences, explore a natural glacier cavity of the Jamtalferner glacier near Galtuer, Austria, October 15, 2021. The Jamtalferner is among Austria's 30 largest glaciers and one of 10 where scientists take very precise measurements annually, documenting the now irreversible decline. REUTERS/Lisi Niesner

Glaciologists Andrea Fischer and Martin Stocker-Waldhuber, from the Austrian Academy of Sciences, explore a natural glacier cavity of the Jamtalferner glacier near Galtuer, Austria, October 15, 2021. Giant ice caves have appeared in glaciers accelerating the melting process faster than expected as warmer air rushes through the ice mass until it collapses. REUTERS/Lisi Niesner

Glaciologists Andrea Fischer and Martin Stocker-Waldhuber, from the Austrian Academy of Sciences, inspect the entrance of a natural glacier cavity of the Jamtalferner glacier near Galtuer, Austria, October 15, 2021. Giant ice caves have appeared in glaciers accelerating the melting process faster than expected as warmer air rushes through the ice mass until it collapses. REUTERS/Lisi Niesner