Data assimilation has become a standard tool for estimating the present state of the climate system based on the wealth of modern observations. It also has the potential of yielding dynamically consistent reconstructions of past climatic states. However, often this method cannot be readily applied to (paleo-) climate data because of their sparse spatial distribution and large uncertainties.

We invite contributions related to the assimilation of climate data from before the second half of the 20th century to the last glacial period and beyond (e.g. the last millennium, the last deglaciation, the Last Glacial Maximum or even the Pliocene).

We encourage reports related to instrumental records as well as palaeoclimate proxy data, equilibrium and long transient simulations, and the application and further development of variational techniques, sequential filtering and statistical methods including the challenges posed by data sparsity and uncertainty.