Supplementary information to chapter 5.8: Modelling the end of an interglacial (MIS 1, 5, 7, 9, 11) Claudia Kubatzki*, Martin Claussen**, Reinhard Calov, Andrey Ganopolski Potsdam-Institute for Climate Impact Research PO Box 601203, 14412 Potsdam *now at Alfred Wegener Institute Bussestr. 24, 27570 Bremerhaven www.awi-bremerhaven.de /People/ show?ckubatzk ( www.pik-potsdam.de /~ kubi ) [email protected]**now at University of Hamburg and Max Planck Institute for Meteorology
Transcript
Supplementary information to chapter 5.8:
Modelling the end of an interglacial(MIS 1, 5, 7, 9, 11)
Claudia Kubatzki*, Martin Claussen**, Reinhard Calov, Andrey Ganopolski
Potsdam-Institute for Climate Impact ResearchPO Box 601203, 14412 Potsdam
*now at Alfred Wegener InstituteBussestr. 24, 27570 Bremerhaven
This first part contains the figures of our book chapter.
Figures II
This second part contains supplementary material.
Model:
CLIMBER-2.3• is an Earth system model of intermediate complexity („weather“ parameterized, coarse spatial resolution except for the inland-ice module);• couples atmosphere, ocean, vegetation, inland ice, carbon cycle;• is driven by changes in insolation and CO2;• simulation period: several thousands of years.
Glacial inception:
At the end of the Eemian interglacial decreasing summer insolation in the northern hemisphere; glacial inception in Northern America at about 117 kyBP; bifurcation (strong positive snow-albedo feedback); sea-level change about 40m until 100 kyBP.
CO2 and insolation (Last Glacial Inception):
longitude longitude
latitude
latitude
Last Glacial Inception:
ice thickness [m]
(Changessince Eemian)
2000 years
Last glacial inceptionas bifurcation
(max. volume lags area by ~ 3 ky)
128 kyBP 117 kyBP
100 kyBP
Atlantic oceanmeridional overturningcirculation
125 kyBP 115 kyBP
100 kyBP
10% 90% Tree fraction
Amplification factors:
• The last glacial inception in the model is mainly caused by changes in the precession.• Changes in the ocean surface as well as of vegetation provide a crucial additional, positive albedo feedback.• Variations in the atmospheric CO2 only act as an amplification factor.
Ice-area (North America):
Temperature (global annual):
Last Glacial Inception:
- Precession initiates ice-sheet growth
- Obliquity / CO2
act as amplifiers
Fixed pre-ind. ... ... or Eemian surface conditions
At the end of the Eemian interglacial:• data show abrupt cooling events, and forest decline in central Europe;• reproducable in the model due to changes in the Atlantic overturning circulation,• caused by disturbing the North Atlantic freshwater balance.
Stadials
D-O events
Temperature in Greenland: CLIMBER-2 and NGRIP
NGRIP members 2004
Freshwaterdisturbances(„IRDs“)
• An ice-free Greenland is a possible second equilibrium state in the model under the insolation forcing of 128 kyr BP. • Timing and extent of northern American glaciation at the end of the Eemian, however, do not depend on the size of the Greenland ice sheet during the Eemian.
Sea-level change (difference to pre-industrial):
Difference between the two runsresulting from two possible equilibrium statesof the Greenland ice sheet
The end of the current interglacial:
In the next 50,000 years („natural“ forcing) only small changes in solar insolation; insolation variations comparably low as during MIS 11 but no significant expansion of inland ice in the model.
Maximum insolation at 65oN
11975MIS 1
CO2 from Vostok
Petit et al. 1999
11975MIS
Berger 1978
meters
Inland-ice area
MIS 10 MIS 11 50 kyAP Present
Height of inland ice at the end of MIS 10 (343kyBP)
Future glaciation ?Sea-level change
Application of our model to a ‘typical GCM setup’:
• The extent to which time-slice simulations of 115 kyr BP are able to reproduce a transient simulation of the last glacial inception is significantly influenced by use of a high-resolution orography and the atmospheric CO2 concentration applied.• Certain combinations of synchronously-run periods and acceleration of the climate model as compared to the ice-sheet module enable a reasonable reproduction of a fully synchronous run.
Annual temperature (difference to pre-industrial):
the transient simulation of the
fully coupled model at 115 ka BP,
a time slice simulation of 115 ka BPwith fixed pre-industrial ice sheets,
a time slice simulation of 115 ka BP
with interactive inland ice model.
Simulation of the last glacial inceptionapplying different levels of climate vs. ice-sheet model acceleration
(coupling period / presetting run time, the black line gives the control run).
