Many questions remain concerning whether or not an ice cap existed during
the mid-Cretaceous period (120–90 Ma). Other than data and observations from
ice-rafted materials, atmospheric general circulation models (AGCMs) may be
appropriate tools to investigate whether changes in atmospheric composition,
land-sea distribution, or oceanic circulation (used as boundary conditions
to constrain the model), provide the climatic conditions that enable ice
caps to be formed.
This study uses an AGCM developed by the Laboratoire de Météorologie
Dynamique (LMD) to perform a set of numerical sensitivity experiments to
investigate plate tectonics (land–sea distribution and orography),
CO2 partial pressure in the atmosphere and changes in
prescribed sea-surface temperatures. The main goals are to quantify the
effect of each forcing factor on the increase of Northern Hemisphere
high-latitude temperatures, and to investigate whether combining these
factors produce temperatures that would allow the ice-sheet formation.