Cryosphere
The cryosphere is the term that refers to anywhere on the Earth's surface where water is frozen solid throughout the year.
Most people are familiar with Glaciers and Ice caps. The cryosphere also includes those areas of the Earth where the ground is frozen solid throughout the year (generally referred to as permafrost).
The cryosphere is an integral part of the global climate system. Change to the cryosphere would be expected to have consequences around the planet.
There is evidence that some of these permanently frozen areas are actually melting at this time. It must be emphasised that this may be the result of a natural cycle that the planet is going through. They have melted before!
map of cryosphere regions
image in public domain.
Source: Wikimedia Commons