In recent Earth history, climate has varied following ~100,000 year, glacial-interglacial cycles with higher and lower temperatures and greenhouse gas concentrations. During the coldest glacial conditions, global mean temperatures were about 5 °C cooler than present with about half as much carbon dioxide in the atmosphere. These cycles were paced by variations in the Earth’s orbit but there is still limited understanding of the types, sizes and timings of the specific processes that led to the temperature and greenhouse gas changes.