the toba super-eruption: micro-scale traces of a global-scale climate event?
TRANSCRIPT
The Toba super-eruption: Micro-scale traces of a global-scale climate event?
Kim M. Cobb
Stacy Carolin, Jessica Moerman, Ellery Ingall, Luke Chambers, Amelia LongoGeorgia Inst. of Technology
Nele Meckler, Jess F. AdkinsCaltech
Lydia FinneyArgonne National Lab
Victoria SmithOxford
Syria Lejau, Jenny Malang, Brian Clark, Alison PritchardGunung Mulu National Park
Andrew TuenUniversity Sans Malaysia
The Tobasuper-eruption:
73.88 ± 0.6 kybp(Storey et al., 2012)
~3,000km3 DRE
VEI of 8
Mulu
Miller and Wark, 2008
Miller and Wark, 2008
Relative eruption magnitudes
Did Toba play a role in an observed “bottleneck” inhuman mitochondrial genetic diversity?
Maybe. [Ambrose 1998]
No. [Petraglia et al., 2007]
see review by Williams et al., 2012
NOTE: H. floresiensislived during this time,discovered in cavewithin Toba ash fall zone
Volcanoes impact global climate: Instrumental data
100x smaller than Toba
300x smaller than Toba
Kelly et al., 1996eruption
Volcanoes impact global climate: Paleoclimate data
IPCC, 2013
data-model comparison provides critical constraints on climate sensitivity: temperature response to changein radiative forcing
Volcanoes impact global climate,but how much?
Fact: models tend to cool more than paleoclimate data suggest
problem with models?(e.g. Timmreck et al., 2010)
or data?(Mann et al., 2012, 2013;Anchukaitis et al., 2012)
IPCC, 2013
Robock et al., 2009
Modeling Toba’s effects in CCSM3
dire effects in first 10yrsdissipate in ~30yrs
BEFORE
+1-4yr
Robock et al., 2009
huge vegetation response across entire tropics in model
need to look i) regionally ii) at hydroclimateiii) and model δ18OR forcomparison to proxy records
Modeling Toba’s effects in MPI-ESM
Timmreck et al., 2012
smaller global responsethan CCSM3, but verylarge in some regions
global TToba
Borneo stalagmites as records of regionalclimate and environmental history
U/Th dated
many overlappingsamples to testreproducibility
oxygen isotopesreflect regionalhydroclimate(Moerman et al.,2013, 2014)
stalagmite oxygenisotope recordsreproducible
reveal many largemillennial-scaleexcursionstowards dryconditions(blue bars = Heinrich events)
Carolin et al., Science 2013
MULU
GREENLAND
HULU
MULU
largest anomalyassociated withToba super-eruption
also captured asout-sized eventin Hulu stalagmiteoxygen isotopes
dry conditionsfor ~1,000yrs
GREENLAND
HULU
MULU
A closer look
Carolin et al., 2013
Wang et al., 2001Wang et al., 2008
Huang et al., 2001
NGRIP, 2004
EPICA, 2006Svensson et al., 2012
ash layer in South China Sea corresponds to initiation of cooler reconstructed SST
Carolin et al., 2013
Wang et al., 2001Wang et al., 2008
Huang et al., 2001
NGRIP, 2004
EPICA, 2006Svensson et al., 2012
multiple sulfate peaks in Antarctic ice core tiedto sulfate peaks in Greenland relationship to Toba
eruption(s)?
A closer look
Research questions:
1) How many times did Toba erupt ~74,000yrs ago?And with what relative sizes?
2) What were the regional hydroclimate impacts ofthe eruption(s)?
3) Did Toba-related climate effects in the WesternPacific have an effect on global climate?Did Toba shape the timing or depth of GS20?
Approach:
Find Toba’s volcanic markers in the Borneo stalagmites.
Compare to oxygen isotope-based climate record in same stalagmites.
Available stalagmites
GOT ASH? Preliminary synchrotron Fe data
Preliminary SIMS Sulfur profile
10μm beam = ~2.2yrs20μm sampling res = 4yrs
data from Stacy Carolin
initiation of regionaldrying
~550yrs
Tobaeruptions?
younger older
Next steps:
Geochemically fingerprinti) Toba ash samplesii) Mulu clay samples
Compare to synchrotron/SIMS scans across iii) Toba horizoniv) known hiatuses
Elements of interest(Fe, Si, S, Br, K, Al)*see review by Frisia et al., 2012
Lane et al., 2013Mermut and Cano, 2001