Transcript Feng He, Jeremy Shakun, Peter Clark, Anders Carlson, Zhengyu Liu

Ice-Age Cycles
Lisiecki and Raymo (2005)
http://commons.wikimedia.org/wiki/File:Five_Myr_Climate_Change.png
2
Orbital Control
Authors
Year
Orbital control
of LGM
Timing of
LGM
Joseph
Adhémar
1842
longer winter (duration)
~10 ka
1860s
weaker insolation in
winter
(Intensity)
~ 10ka
1930s
weaker insolation in
summer
(Intensity)
~22 ka
James Croll
Milutin
Milankovic
Hays, Imbrie,
Shackleton
1976
Confirmed Milankovic theory with 450 kyr
oxygen isotope records from the sediments of
the Southern Ocean
3
Problem of SH-lead
“Fly in the ointment”
4
Recent hypotheses for the SH-control
of ice age cycles
5
2009
2007
6
2008
Data-model comparison: testing
mechanisms of the last deglaciation
IPCC-type
coupled climate model
High-res proxy data
Loutre, M. F. (2003)
9
INCITE Supercomputing Support
Model:
CCSM3 (T31_gx3v5) + dynamic vegetation
ATM
3.75(lon) x 3.75(lat) x 26(level)
OCN
~3 (lon/lat) x 25 (level)
Peak performance: 120 model years per day
21,000 years in 6 months
Data storage:
over 300 TB
10
TraCE simulations
 Transient boundary conditions
 Orbital forcing
 GHGs
 Ice sheets
 Meltwater forcing (AMOC)
11
Five simulations
 Simulation ALL (ORBIT+GHG+Ice sheets+AMOC)
 Simulation ORB (ORBIT)
 Simulation GHG (GHG)
 Simulation ICE (Ice sheets)
 Simulation MOC (AMOC)
12
Ice sheet changes (once per 500 years)
He 2011
13
14
15
Transient simulation of the last deglaciation
Simulation ALL
16
17
18
19
20
21
TraCE simulation of the SH deglaciation
TraCE simulation of the SH deglaciation
Bipolar seesaw
early deglacial warming
in the SH
(Simulation ALL vs. single forcing simulations)
24
bipolar seesaw (19-17 ka)
25
Deglacial CO2 rise
synchronous deglacial warming and eventually reach
and sustain complete deglaciation
(Simulation ALL vs. single forcing simulations)
26
CO2-induced global warming (17-15 ka)
27
Mechanism of the terminations
What’s causing the deglacial CO2 rise?
28
Heinrich events & deglacial CO2 rise
29
Deglacial CO2 rise due to Southern Ocean processes
NH meltwater
Early warming of the Southern Ocean
deglacial CO2 rise
31
2006
Large NH Ice sheets at LGM
NH meltwater
Early warming of the Southern Ocean
deglacial CO2 rise
32
2010