Advance in research on the Mid-Brunhes climatic transition published in Nature

The Mid-Brunhes climatic transition occurred about 430,000 years ago: earlier interglacials were cooler and had lower CO2 concentration than later ones. The cause of this transition was unclear. Based on climate simulations with the model LOVECLIM, Qiuzhen Yin (Collaborateur Scientifique of FRS-FNRS and researcher from ELIC) showed that in response to insolation changes only, southern westerlies and feedbacks between sea ice, temperature, evaporation and salinity caused vigorous Southern Ocean ventilation and cooler deep Ocean during the earlier interglacials, suggesting that the Mid-Brunhes transition may in fact have resulted from a series of individual interglacial responses to various combinations of insolation conditions. These findings are a first step towards understanding the magnitude change of the interglacial carbon dioxide concentration around 430,000 years ago.

Insolation-induced annual mean differences in stream function, ventilation age and mixed-layer depth between the averages of the pre-MBE and post-MBE interglacials.

http://www.nature.com/nature/journal/v494/n7436/full/nature11790.html