Session: Glacial Climates (LGM, Last deglaciation, Ice sheet uncertainties, Glacial-interglacial cycles)
Author: Uwe Mikolajewicz / firstname.lastname@example.org / Max-Planck-Institut f. Meteorologie
Co-author: Florian Ziemen, Max-Planck-Institut f. Meteorologie;
Marie Kapsch, Max-Planck-Institut f. Meteorologie;
Virna Meccia, Max-Planck-Institut f. Meteorologie;
One of the major challenges in climate modelling is the simulation of glacial-interglacial transitions. Here we presents results from our first successful attempt to simulate a substantial part of the last glacial cycle with the ECHAM5/MPIOM AOGCM coupled interactively to a northern hemisphere set up of the dynamical ice sheet model PISM. This model is integrated from the late Glacial into the Holocene using insolation and greenhouse gas concentrations as transient forcing. The land sea mask remains fixed at the LGM state. River routing and surface elevation for the atmospheric model component are calculated interactively. To make these long simulations feasible, the atmosphere is accelerated by a factor of 10 relative to the other model components using a periodical-synchronous coupling technique. A mini-ensemble with different initial conditions is run. Additionally, one simulation is run fully synchronously without acceleration in the atmosphere.
In all simulation the northern hemispheric deglaciation starts around 20 kyr BP, the warming at around 17 kyr BP. During the deglaciation the interactive river routing has a strong impact on the simulated NAMOC, which weakens in the course of the deglaciation and collapses for part of the time, before it recovers in the early Holocene.