Holocene volcanic history as recorded in the sulfate stratigraphy of the European Project for Ice Coring in Antarctica Dome C (EDC96) ice core

Abstract

A detailed history of Holocene volcanism was reconstructed using the sulfate record of the European Project for Ice Coring in Antarctica Dome C (EDC96) ice core. This first complete Holocene volcanic record from an Antarctic core provides a reliable database to compare with long records from Antarctic and Greenland ice cores. A threshold method based on statistical treatment of the lognormal sulfate flux distribution was used to differentiate volcanic sulfate spikes from sulfate background concentrations. Ninety‐six eruptions were identified in the EDC96 ice core during the Holocene, with a mean of 7.9 events per millennium. The frequency distribution (events per millennium) showed that the last 2000 years were a period of enhanced volcanic activity. EDC96 volcanic signatures for the last millennium are in good agreement with those recorded in other Antarctic ice cores. For older periods, comparison is in some cases less reliable, mainly because of dating uncertainties. Sulfate depositional fluxes of individual volcanic events vary greatly among the different cores. A volcanic flux normalization (volcanic flux/Tambora flux ratio) was used to evaluate the relative intensity of the same event recorded at different sites in the last millennium. Normalized flux variability for the same event showed the highest value in the 1100–1500 AD period. This pattern could mirror changes in regional transport linked to climatic variations such as slight warming stages in the Southern Hemisphere (Southern Hemisphere Medieval Warming–like period?).

Southern Ocean sea-ice extent, productivity and iron flux over the past eight glacial cycles

“…Estimates of the annual downward transport from the stratosphere to the troposphere 11 , comparisons of the stratospheric aerosol burden in non-volcanic and volcanic periods, and modelling studies 10 suggest that the volcanic input during background periods is ,10% of the deposition of SO 4 22 to the Antarctic ice sheet. Volcanic input during eruptive events 12 can dominate the SO 4 22 budget for 1-3 yr, but fills only a small time fraction, representing (for example) only about 6% of the Holocene sulphate budget 13 . In deeper ice, these spikes become diffuse, and eventually cannot be identified against the background: as a result there is no objective way to remove their influence.…”

Volcanic forcing of climate over the past 1500 years: An improved ice core‐based index for climate models

“…During the past 10 years a large number of new ice cores have been recovered, and most of these were analyzed using continuous sulfate measurements [Cole-Dai et al 1997Sommer et al 2000;Bigler et al 2002;Palmer et al 2002;Stenni et al 2002;Budner and Cole-Dai, 2003;Dixon et al 2004;Traufetter et al, 2004;Castellano et al, 2005;Kurbatov et al, 2006]. This offers the potential for a dramatic improvement to reconstruct the volcanic forcing index over the past centuries and millennia.…”

Technical details concerning development of a 1200 yr proxy index for global volcanism

“…In our reconstruction we do not find a large 1453 signal in Greenland records and use a 1456 estimate from Castellano et al (2005), which was what we considered the best estimate at the time (subsequently we now think the Castellano et al (2005) data suggest 1457 rather than 1456). Improved dating of the event in a Law Dome core (Plummer et al, 2012) now suggests that Kuwae may have erupted in mid-late 1457.…”