Impact of Orbital Parameters and Greenhouse Gas on the Climate of MIS 7 and MIS 5 Glacial Inceptions

• Published in: Revista Latina de Sociología
• Main Authors: Colleoni, F., Masina, S., Cherchi, A., Iovino, D.
• Other Authors: Colleoni, F.; Ctr Euromediterraneo Cambiamenti Climat, Bologna, Italy, Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia, Cherchi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia, Iovino, D.; Ctr Euromediterraneo Cambiamenti Climat, Bologna, Italy, Ctr Euromediterraneo Cambiamenti Climat, Bologna, Italy, Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Meteorological Society 2014
• Subjects: Arctic Oscillation; Teleconnections; Greenhouse gases; Glaciation; Paleoclimate; 02. Cryosphere::02.03. Ice cores::02.03.05. Paleoclimate; Arctic
• Online Access: http://hdl.handle.net/2122/9522; http://journals.ametsoc.org/doi/full/10.1175/JCLI-D-13-00754.1; https://doi.org/10.1175/JCLI-D-13-00754.1

This work explores the impact of orbital parameters and greenhouse gas concentrations on the climate of marine isotope stage (MIS) 7 glacial inception and compares it to that of MIS 5. The authors use a coupled atmosphere-ocean general circulation model to simulate the mean climate state of six time slices at 115, 122, 125, 229, 236, and 239 kyr, representative of a climate evolution from interglacial to glacial inception conditions. The simulations are designed to separate the effects of orbital parameters from those of greenhouse gas (GHG). Their results show that, in all the time slices considered, MIS 7 boreal lands mean annual climate is colder than the MIS 5 one. This difference is explained at 70% by the impact of the MIS 7 GHG. While the impact of GHG over Northern Hemisphere is homogeneous, the difference in temperature between MIS 7 and MIS 5 due to orbital parameters differs regionally and is linked with the Arctic Oscillation. The perennial snow cover is larger in all the MIS 7 experiments compared to MIS 5, as a result of MIS 7 orbital parameters, strengthened by GHG. At regional scale, Eurasia exhibits the strongest response to MIS 7 cold climate with a perennial snow area 3 times larger than in MIS 5 experiments. This suggests that MIS 7 glacial inception is more favorable over this area than over North America. Furthermore, at 239 kyr, the perennial snow covers an area equivalent to that of MIS 5 glacial inception (115 kyr). The authors suggest that MIS 7 glacial inception is more extensive than MIS 5 glacial inception over the high latitudes. Italian Ministry of Education, University and Research Ministry for Environment, Land and Sea through the project GEMINA Published 8918-8933 4A. Clima e Oceani JCR Journal open