Berger, André
[UCL]
Yin, Qiuzhen
[UCL]
One of the fundamental questions regarding Quaternary climate change is why the amplitude of glacial-interglacial cycles increased significantly after the Mid-Brunhes Event (MBE) about 430 ky ago with generally cooler pre-MBE interglacials and warmer post-MBE ones. Our recent simulations of the nine interglacials of the past 800,000 years provide important clues for answering this question. The individual contributions of insolation and CO2 to the last nine interglacials are quantified through simulations with an Earth system model of intermediate complexity and using the factor separation technique. The interglacials are compared in terms of their forcings and climate response. Our findings are: (1) In the explanation of the warmer post-MBE interglacials, boreal winter – or austral summer - is a key season and the Southern Hemisphere plays a more important role than the Northern one. (2) MBE appears mainly in climatic variables principally influenced by CO2, like temperature. It does not appear in variables mainly driven by insolation like precipitation and tree fraction. (3) MBE is mainly a characteristic of the global mean temperature and of the southern high latitudes climate. These findings are coherent with proxy records that MBE is mainly a characteristic in the marine oxygen isotope data – a proxy of global signal - and in the proxy records of the southern hemisphere, and it does not appear in some regional records from the northern hemisphere.


Bibliographic reference |
Berger, André ; Yin, Qiuzhen. Intercomparison of the last nine interglacials in response to insolation and CO2.EGU General Assembly (Vienna, du 03/04/2011 au 08/04/2011). |
Permanent URL |
http://hdl.handle.net/2078/122743 |