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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

Possible correlations between millennial scale climate shifts and knownvolcanic eruptions.(a) All known very large (M ≥ 7)NH volcanic eruptions with radiometric ages (red circles) shifted withinerror to previously documented rapid cooling events (blue squares).(b) Known large radiometrically-dated(M ≥ 6) SH volcanic eruptions (redcircles) shifted within error to previously documented Greenland warmingevents (yellow squares). The small grey horizontal arrows in both panelsrepresent the total shift required to obtain a match to an abrupt climateevent. All eight NH eruptions occur within error of an abrupt Greenlandcooling event, and all five SH eruptions timings are within error of awarming event. Dashed lines with question marks represent abrupt climateshifts possibly linked to yet unidentified eruptions. The label‘Okataina’ at 33.5 ka BP refers to twodistinct eruptions responsible for Okataina Units K and L. The two yellowcircles indicate previously published correlations.
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f3: Possible correlations between millennial scale climate shifts and knownvolcanic eruptions.(a) All known very large (M ≥ 7)NH volcanic eruptions with radiometric ages (red circles) shifted withinerror to previously documented rapid cooling events (blue squares).(b) Known large radiometrically-dated(M ≥ 6) SH volcanic eruptions (redcircles) shifted within error to previously documented Greenland warmingevents (yellow squares). The small grey horizontal arrows in both panelsrepresent the total shift required to obtain a match to an abrupt climateevent. All eight NH eruptions occur within error of an abrupt Greenlandcooling event, and all five SH eruptions timings are within error of awarming event. Dashed lines with question marks represent abrupt climateshifts possibly linked to yet unidentified eruptions. The label‘Okataina’ at 33.5 ka BP refers to twodistinct eruptions responsible for Okataina Units K and L. The two yellowcircles indicate previously published correlations.

Mentions: However, very recent research focussing on the last 500 years has demonstrated theimportance of asymmetric hemispheric cooling induced by sulphate aerosol injections2021 on atmospheric circulation. Observational, modelling, and proxystudies now firmly implicate 20th Century anthropogenic sulphate aerosolemissions with greater NH cooling compared to the SH, resulting in southward migrationof the Intertropical Convergence Zone (ITCZ), drying at NH low latitudes, and morerainfall at SH low latitudes2223. Recent research also demonstratesthat this same asymmetric cooling effect occurred following the injection of sulphateaerosols into the stratosphere following large volcanic eruptions over the last 100years (based on instrumental data)20 and 500 years (based on stalagmiterainfall proxy data)21. These studies collectively demonstrate that overthe last few centuries NH aerosols (volcanogenic and anthropogenic) forced the ITCZ tothe south by cooling the NH relative to the SH, and that SH eruptions forced northwardITCZ migration. The atmospheric and temperature response associated with the Tobaeruption is therefore consistent with the recently detected climate response to morerecent (but far smaller) NH eruptions. We suggest that the Toba eruption initiatedsouthward ITCZ migration by inducing a NH-SH temperature asymmetry, which resulted inmore SAM rainfall but reduced rainfall in the NH low latitudes (e.g., the EASM),consistent with speleothem-based evidence (Fig. 1), and identicalto the response to NH eruptions over the last 500 years. A southward displaced ITCZwould have shifted Hadley circulation cells to the south, compressing the SH Polar Cell,forcing the SH Polar Front southward, and resulting in locally warmer Antarctictemperatures (Supplementary Information).The opposite response would have occurred in the NH, where atmospheric reorganisationwould have resulted in extreme and sudden cooling in Greenland and extension of NHglacial and sea ice, characteristics associated with the abrupt transition between DO-20and Greenland Stadial (GS) 20 occurring at that time. We propose that the positivefeedbacks following NH eruptions (e.g., NH sea ice expansion, NH continental glacierexpansion, increased NH albedo, and AMOC weakening) prolonged the climatic response tothe Toba eruption by several hundred years, not dissimilar to recent results suggestingthat Little Ice Age cooling was initiated by NH volcanism in the 13thCentury but was sustained over hundreds of years by a positive feedback involving seaice and oceanic circulation24. The timing of the Toba supereruption isconsistent with the abrupt cooling into GS20, although this seems superimposed on acooling trend that began ~100 years earlier, potentially linked todecreasing insolation. However, the Toba eruption is nearly indistinguishable from theinception of Antarctic warming (Figs 1 and 2) (Supplementary Information). Wesuggest that large NH eruptions that occurred during interstadials abruptly endedGreenland interstadial conditions and promoted a rapid transition to stadial conditions,which were favoured during much of the Last Glacial because of low atmosphericgreenhouse gas concentrations and insolation conditions. Conversely, large NH eruptionsthat occurred during already cold conditions resulted in less Greenland cooling but ledto glacier extension and Heinrich Events. This is supported by the establishedassociation of the 39.280 ± 0.110 ka BPCampanian Ignimbrite supereruption of the Campi Flegrei supervolcano with GS9 andHeinrich Event 4 (HE4)25. We also note that the inception of HE5a at~53 ka BP is indistinguishable from the timing of the magnitude(M) 7 Ischia eruption (53 ± 3.3 ka BP).Additionally, all eight very large (M ≥ 7;Tambora-sized or larger) Pleistocene NH eruptions (see Supplementary Information for selection criteria used)are within error of a NH cooling event (Fig. 3), and Monte Carlosimulations demonstrate that this relationship is significant at the 95% confidencelevel (Supplementary Information) (Fig. 4).


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

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

Possible correlations between millennial scale climate shifts and knownvolcanic eruptions.(a) All known very large (M ≥ 7)NH volcanic eruptions with radiometric ages (red circles) shifted withinerror to previously documented rapid cooling events (blue squares).(b) Known large radiometrically-dated(M ≥ 6) SH volcanic eruptions (redcircles) shifted within error to previously documented Greenland warmingevents (yellow squares). The small grey horizontal arrows in both panelsrepresent the total shift required to obtain a match to an abrupt climateevent. All eight NH eruptions occur within error of an abrupt Greenlandcooling event, and all five SH eruptions timings are within error of awarming event. Dashed lines with question marks represent abrupt climateshifts possibly linked to yet unidentified eruptions. The label‘Okataina’ at 33.5 ka BP refers to twodistinct eruptions responsible for Okataina Units K and L. The two yellowcircles indicate previously published correlations.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: Possible correlations between millennial scale climate shifts and knownvolcanic eruptions.(a) All known very large (M ≥ 7)NH volcanic eruptions with radiometric ages (red circles) shifted withinerror to previously documented rapid cooling events (blue squares).(b) Known large radiometrically-dated(M ≥ 6) SH volcanic eruptions (redcircles) shifted within error to previously documented Greenland warmingevents (yellow squares). The small grey horizontal arrows in both panelsrepresent the total shift required to obtain a match to an abrupt climateevent. All eight NH eruptions occur within error of an abrupt Greenlandcooling event, and all five SH eruptions timings are within error of awarming event. Dashed lines with question marks represent abrupt climateshifts possibly linked to yet unidentified eruptions. The label‘Okataina’ at 33.5 ka BP refers to twodistinct eruptions responsible for Okataina Units K and L. The two yellowcircles indicate previously published correlations.
Mentions: However, very recent research focussing on the last 500 years has demonstrated theimportance of asymmetric hemispheric cooling induced by sulphate aerosol injections2021 on atmospheric circulation. Observational, modelling, and proxystudies now firmly implicate 20th Century anthropogenic sulphate aerosolemissions with greater NH cooling compared to the SH, resulting in southward migrationof the Intertropical Convergence Zone (ITCZ), drying at NH low latitudes, and morerainfall at SH low latitudes2223. Recent research also demonstratesthat this same asymmetric cooling effect occurred following the injection of sulphateaerosols into the stratosphere following large volcanic eruptions over the last 100years (based on instrumental data)20 and 500 years (based on stalagmiterainfall proxy data)21. These studies collectively demonstrate that overthe last few centuries NH aerosols (volcanogenic and anthropogenic) forced the ITCZ tothe south by cooling the NH relative to the SH, and that SH eruptions forced northwardITCZ migration. The atmospheric and temperature response associated with the Tobaeruption is therefore consistent with the recently detected climate response to morerecent (but far smaller) NH eruptions. We suggest that the Toba eruption initiatedsouthward ITCZ migration by inducing a NH-SH temperature asymmetry, which resulted inmore SAM rainfall but reduced rainfall in the NH low latitudes (e.g., the EASM),consistent with speleothem-based evidence (Fig. 1), and identicalto the response to NH eruptions over the last 500 years. A southward displaced ITCZwould have shifted Hadley circulation cells to the south, compressing the SH Polar Cell,forcing the SH Polar Front southward, and resulting in locally warmer Antarctictemperatures (Supplementary Information).The opposite response would have occurred in the NH, where atmospheric reorganisationwould have resulted in extreme and sudden cooling in Greenland and extension of NHglacial and sea ice, characteristics associated with the abrupt transition between DO-20and Greenland Stadial (GS) 20 occurring at that time. We propose that the positivefeedbacks following NH eruptions (e.g., NH sea ice expansion, NH continental glacierexpansion, increased NH albedo, and AMOC weakening) prolonged the climatic response tothe Toba eruption by several hundred years, not dissimilar to recent results suggestingthat Little Ice Age cooling was initiated by NH volcanism in the 13thCentury but was sustained over hundreds of years by a positive feedback involving seaice and oceanic circulation24. The timing of the Toba supereruption isconsistent with the abrupt cooling into GS20, although this seems superimposed on acooling trend that began ~100 years earlier, potentially linked todecreasing insolation. However, the Toba eruption is nearly indistinguishable from theinception of Antarctic warming (Figs 1 and 2) (Supplementary Information). Wesuggest that large NH eruptions that occurred during interstadials abruptly endedGreenland interstadial conditions and promoted a rapid transition to stadial conditions,which were favoured during much of the Last Glacial because of low atmosphericgreenhouse gas concentrations and insolation conditions. Conversely, large NH eruptionsthat occurred during already cold conditions resulted in less Greenland cooling but ledto glacier extension and Heinrich Events. This is supported by the establishedassociation of the 39.280 ± 0.110 ka BPCampanian Ignimbrite supereruption of the Campi Flegrei supervolcano with GS9 andHeinrich Event 4 (HE4)25. We also note that the inception of HE5a at~53 ka BP is indistinguishable from the timing of the magnitude(M) 7 Ischia eruption (53 ± 3.3 ka BP).Additionally, all eight very large (M ≥ 7;Tambora-sized or larger) Pleistocene NH eruptions (see Supplementary Information for selection criteria used)are within error of a NH cooling event (Fig. 3), and Monte Carlosimulations demonstrate that this relationship is significant at the 95% confidencelevel (Supplementary Information) (Fig. 4).

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