Chronic hypobaric hypoxia (lack of oxygen): where the expedition will encounter equivalent altitudes up around 3, 800m due to the extreme cold temperatures and distance from the Equator which further decreases atmospheric pressure.
The rest of the team will continue with their 2, 000-mile (3, 219km) trek as part of the "Coldest Journey" expedition as they aim to become the first people in history to cross the Antarctic in winter.