  Habitable planets are commonly imagined to be temperate planets like Earth,
with areas of open ocean and warm land. In contrast, planets in snowball
states, where oceans are entirely ice-covered, are believed to be inhospitable.
However, we show using a general circulation model that terrestrial planets in
the inner habitable zone are able to support large unfrozen areas of land while
in a snowball state. Due to their lower albedo, these unfrozen regions reach
summer temperatures in excess of 10 $^\circ$Celsius. Such conditions permit
CO$_2$ weathering, suggesting that continental weathering can provide a
mechanism for trapping planets in stable snowball states. The presence of land
areas with warm temperatures and liquid surface water motivates a more-nuanced
understanding of habitability during these snowball events.

Earth and Planetary Astrophysics