How did the hydrologic cycle respond to the two-phase mystery interval?

• Main Authors: Broecker, Wallace S., Putnam, Aaron Ervin
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2012
• Subjects: Hydrologic cycle; Geochemistry; Antarctic; Southern Ocean; Antarc*; Antarctica; Sea ice
• Online Access: https://doi.org/10.7916/D81V5QN2

Lake Estancia’s transition from a Big Dry episode during the first half of the Mystery Interval to a Big Wet episode during the second half has equivalents in records from across the planet. At the time of this transition, Chinese monsoons experienced pronounced weakening, closed-basin lakes in both the Great Basin of the western United States and in the southern Altiplano of South America underwent a major expansion, mountain glaciers in Southern Hemisphere middle latitudes had retreated, and the rates of increase of CO2 and of d18O in Antarctic ice underwent a decrease. Finally, the precipitous drop in dust rain over Antarctica and the Southern Ocean terminated as did a similar drop in the 13C to 12C ratio in atmospheric CO2. These changes are consistent with a southward shift of the thermal equator. The cause of such a shift is thought to be an expansion of sea ice caused by a shutdown in deep water production in the northern Atlantic. This creates a dilemma because a similar southward shift is an expected consequence of the Heinrich event #1 which initiated the Mystery Interval.