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Was millennial scale climate change during the Last Glacial triggered by explosive volcanism?

Baldini JU, Brown RJ, McElwaine JN - Sci Rep (2015)

Bottom Line: Additionally, previous research reported a strong statistical correlation between the timing of Southern Hemisphere volcanism and Dansgaard-Oeschger (DO) events (>99% confidence), but did not identify a causative mechanism.Volcanic aerosol-induced asymmetrical hemispheric cooling over the last few hundred years restructured atmospheric circulation in a similar fashion as that associated with Last Glacial millennial-scale shifts (albeit on a smaller scale).This resulted in Greenland cooling, Antarctic warming, and a southward shifted ITCZ.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Sciences, University of Durham, Durham, DH1 3LE, UK.

ABSTRACT
The mechanisms responsible for millennial scale climate change within glacial time intervals are equivocal. Here we show that all eight known radiometrically-dated Tambora-sized or larger NH eruptions over the interval 30 to 80 ka BP are associated with abrupt Greenland cooling (>95% confidence). Additionally, previous research reported a strong statistical correlation between the timing of Southern Hemisphere volcanism and Dansgaard-Oeschger (DO) events (>99% confidence), but did not identify a causative mechanism. Volcanic aerosol-induced asymmetrical hemispheric cooling over the last few hundred years restructured atmospheric circulation in a similar fashion as that associated with Last Glacial millennial-scale shifts (albeit on a smaller scale). We hypothesise that following both recent and Last Glacial NH eruptions, volcanogenic sulphate injections into the stratosphere cooled the NH preferentially, inducing a hemispheric temperature asymmetry that shifted atmospheric circulation cells southward. This resulted in Greenland cooling, Antarctic warming, and a southward shifted ITCZ. However, during the Last Glacial, the initial eruption-induced climate response was prolonged by NH glacier and sea ice expansion, increased NH albedo, AMOC weakening, more NH cooling, and a consequent positive feedback. Conversely, preferential SH cooling following large SH eruptions shifted atmospheric circulation to the north, resulting in the characteristic features of DO events.

No MeSH data available.


Related in: MedlinePlus

Low latitude atmospheric circulation and high latitude temperature recordsspanning the time interval during which the 74 ka Tobasuper-eruption occurred.(a) The NGRIP ice core δ18O record,(b) the SC03 stalagmite δ18O recordfrom Secret Cave, Gunung Mulu National Park, Borneo32,(c) the El Condor Cave (ELC) stalagmiteδ18O record from northern Peru6, and (d) the EDML δ18O record fromAntarctica33. The records are arranged by latitude. Thegrey box indicates the timing of the Toba supereruption at73.72 ka BP. The ice core records are synchronised on theAICC2012 timescale, and both stalagmite records are dated independentlyusing 230Th dating.
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f1: Low latitude atmospheric circulation and high latitude temperature recordsspanning the time interval during which the 74 ka Tobasuper-eruption occurred.(a) The NGRIP ice core δ18O record,(b) the SC03 stalagmite δ18O recordfrom Secret Cave, Gunung Mulu National Park, Borneo32,(c) the El Condor Cave (ELC) stalagmiteδ18O record from northern Peru6, and (d) the EDML δ18O record fromAntarctica33. The records are arranged by latitude. Thegrey box indicates the timing of the Toba supereruption at73.72 ka BP. The ice core records are synchronised on theAICC2012 timescale, and both stalagmite records are dated independentlyusing 230Th dating.

Mentions: Here we use published ice core (synchronised on the AICC2012 chronology13), volcanological, and speleothem-based evidence to argue that DO events weretriggered by asymmetrical hemispheric cooling caused by explosive SH volcanic eruptions.Conversely, we argue that very large NH eruptions forced abrupt Greenland cooling eventsand, under the right conditions, were associated with large ice rafting events (HeinrichStadials). This perspective is consistent with recent results suggesting that icerafting events were a consequence of, but did not trigger, NH cooling14.Large explosive volcanic eruptions are conventionally thought to result in globalcooling for several years following the eruption, based on the concept thatstratospheric volcanogenic sulphate aerosols reflect solar radiation and cool the planetessentially uniformly. Large low latitude eruptions are therefore often considered themost climatologically significant because low latitudes receive a disproportionatelyhigh amount of insolation15, although in-depth studies highlightconsiderable complexities in the climate response to eruptions based on ejecta volume,sulphate content, explosivity, and latitude1617 (see Supplementary Information). However, global coolingdoes not seem to have occurred following several large, well-documented Pleistoceneeruptions. For example, the Toba supereruption at ~74 ka BP isfollowed by lower NGRIP δ18O (Greenland cooling) but higherEDML δ18O values (Antarctic warming), thereby providing nosupport for homogeneous global cooling18. Similarly, evidence from LakeMalawi in east Africa does not show any evidence for substantial cooling at lowlatitudes19. The apparent absence of ‘volcanicwinter’ in response to the largest eruption of the Quaternary is enigmaticwhen considered from the conventional perspective. Similarly puzzling is the apparentstrengthening of the SAM and AM and concomitant weakening of the EASM coinciding withthe Toba eruption (Fig. 1).


Was millennial scale climate change during the Last Glacial triggered by explosive volcanism?

Baldini JU, Brown RJ, McElwaine JN - Sci Rep (2015)

Low latitude atmospheric circulation and high latitude temperature recordsspanning the time interval during which the 74 ka Tobasuper-eruption occurred.(a) The NGRIP ice core δ18O record,(b) the SC03 stalagmite δ18O recordfrom Secret Cave, Gunung Mulu National Park, Borneo32,(c) the El Condor Cave (ELC) stalagmiteδ18O record from northern Peru6, and (d) the EDML δ18O record fromAntarctica33. The records are arranged by latitude. Thegrey box indicates the timing of the Toba supereruption at73.72 ka BP. The ice core records are synchronised on theAICC2012 timescale, and both stalagmite records are dated independentlyusing 230Th dating.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663491&req=5

f1: Low latitude atmospheric circulation and high latitude temperature recordsspanning the time interval during which the 74 ka Tobasuper-eruption occurred.(a) The NGRIP ice core δ18O record,(b) the SC03 stalagmite δ18O recordfrom Secret Cave, Gunung Mulu National Park, Borneo32,(c) the El Condor Cave (ELC) stalagmiteδ18O record from northern Peru6, and (d) the EDML δ18O record fromAntarctica33. The records are arranged by latitude. Thegrey box indicates the timing of the Toba supereruption at73.72 ka BP. The ice core records are synchronised on theAICC2012 timescale, and both stalagmite records are dated independentlyusing 230Th dating.
Mentions: Here we use published ice core (synchronised on the AICC2012 chronology13), volcanological, and speleothem-based evidence to argue that DO events weretriggered by asymmetrical hemispheric cooling caused by explosive SH volcanic eruptions.Conversely, we argue that very large NH eruptions forced abrupt Greenland cooling eventsand, under the right conditions, were associated with large ice rafting events (HeinrichStadials). This perspective is consistent with recent results suggesting that icerafting events were a consequence of, but did not trigger, NH cooling14.Large explosive volcanic eruptions are conventionally thought to result in globalcooling for several years following the eruption, based on the concept thatstratospheric volcanogenic sulphate aerosols reflect solar radiation and cool the planetessentially uniformly. Large low latitude eruptions are therefore often considered themost climatologically significant because low latitudes receive a disproportionatelyhigh amount of insolation15, although in-depth studies highlightconsiderable complexities in the climate response to eruptions based on ejecta volume,sulphate content, explosivity, and latitude1617 (see Supplementary Information). However, global coolingdoes not seem to have occurred following several large, well-documented Pleistoceneeruptions. For example, the Toba supereruption at ~74 ka BP isfollowed by lower NGRIP δ18O (Greenland cooling) but higherEDML δ18O values (Antarctic warming), thereby providing nosupport for homogeneous global cooling18. Similarly, evidence from LakeMalawi in east Africa does not show any evidence for substantial cooling at lowlatitudes19. The apparent absence of ‘volcanicwinter’ in response to the largest eruption of the Quaternary is enigmaticwhen considered from the conventional perspective. Similarly puzzling is the apparentstrengthening of the SAM and AM and concomitant weakening of the EASM coinciding withthe Toba eruption (Fig. 1).

Bottom Line: Additionally, previous research reported a strong statistical correlation between the timing of Southern Hemisphere volcanism and Dansgaard-Oeschger (DO) events (>99% confidence), but did not identify a causative mechanism.Volcanic aerosol-induced asymmetrical hemispheric cooling over the last few hundred years restructured atmospheric circulation in a similar fashion as that associated with Last Glacial millennial-scale shifts (albeit on a smaller scale).This resulted in Greenland cooling, Antarctic warming, and a southward shifted ITCZ.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Sciences, University of Durham, Durham, DH1 3LE, UK.

ABSTRACT
The mechanisms responsible for millennial scale climate change within glacial time intervals are equivocal. Here we show that all eight known radiometrically-dated Tambora-sized or larger NH eruptions over the interval 30 to 80 ka BP are associated with abrupt Greenland cooling (>95% confidence). Additionally, previous research reported a strong statistical correlation between the timing of Southern Hemisphere volcanism and Dansgaard-Oeschger (DO) events (>99% confidence), but did not identify a causative mechanism. Volcanic aerosol-induced asymmetrical hemispheric cooling over the last few hundred years restructured atmospheric circulation in a similar fashion as that associated with Last Glacial millennial-scale shifts (albeit on a smaller scale). We hypothesise that following both recent and Last Glacial NH eruptions, volcanogenic sulphate injections into the stratosphere cooled the NH preferentially, inducing a hemispheric temperature asymmetry that shifted atmospheric circulation cells southward. This resulted in Greenland cooling, Antarctic warming, and a southward shifted ITCZ. However, during the Last Glacial, the initial eruption-induced climate response was prolonged by NH glacier and sea ice expansion, increased NH albedo, AMOC weakening, more NH cooling, and a consequent positive feedback. Conversely, preferential SH cooling following large SH eruptions shifted atmospheric circulation to the north, resulting in the characteristic features of DO events.

No MeSH data available.


Related in: MedlinePlus