A 10‐century comparison of prominent bipolar volcanic events in ice cores

Abstract

Measurements of key chemical and physical parameters made along continuous and selected long sections of polar ice cores provide reliable past snow accumulation rates and other environmental records. The prime accumulation indicators include variations found in the stable isotopes, ionic constituents, and acidity concentration levels; and physical changes in the strata and structure. Cross correlations of the time series curves resulting from multiparameter analyses of ice cores from Antarctica (NBY89, SP78, BS68) and Greenland (CR74, D3 81, D3 18C) have been made. The results permit construction of a bipolar chemical stratigraphy chronology of volcanic events that is coherent with the δ 18O and Electrical Conductivity Method data sets and consistent back‐in‐time with historically recorded volcanic activity. A bihemispheric comparison of high non‐sea‐salt SO42− peaks shows strong correlation at 1885, 1836, 1816, 1810, 1459, 1346, 1287, 1278, 1259, 1228, and 1168 A.D. at time of snow deposit. The prominent 1259 A.D. volcanic signal appears to be a significant bipolar ice core index horizon.

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

“…Prior to that time Antarctic dating is more uncertain, for it is difficult to find any confident matchups with the Greenland records, especially since "false positives" -simultaneous mid/high latitude eruptions in both hemispheresare a distinct possibility. Cross-checking of Antarctic records (cf., Langway et al, 1995) indicates that the records seem to be consistent, but the fits are not airtight. Although it is not possible to make a precise uncertainty estimate of pre-1258 Antarctic peaks, an educated guess would be that the chronology of Antarctic eruptions prior to 1258 is accurate to within 2-3 yr.…”

“…The 13th century pulse of eruptions originally identified by Langway et al (1995) also shows some differences; at least part of this is (we suspect) due to Taylor Dome indications (again, see Sect. 2.4) of at least one coincidental local eruption at the time of one of the Greenland eruptions previously inferred by all investigators (including ourselves -Crowley, 2000) as being tropical in origin.…”

“…Three other Greenland cores (Crete, Dye3, and GRIP) have near-annual scale electrical conductivity measurements (ECM) and spot sulphate measurements. Spot sulphate measurements (Langway et al, 1995;Clausen et al, 1997) were used to scale the higher resolution ECM record in these cores to sulphate. Three additional cores were used in the upper part of the record to better constrain estimates over the last two centuries and develop a bias estimate for the fewer number of records over the entire length of the series.…”

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

“…The evidence from both polar regions also helps to distinguish the tropical eruption from high-latitude ones. Crowley [2000, an update of Crowley andKim, 1999] also developed a volcanic forcing index for the same period based essentially on Crête [Hammer et al, 1980] and GISP2 with some additional information embedded using the Arctic-Antarctic comparisons by Langway et al [1995]. combined five ice core sulfate records (GISP2, GR89, siteA from Greenland and Siple, Dyer Plateau from Antarctica) and reconstructed an annually and zonally averaged volcanic forcing history for the past 500 years.…”

Modeling the temperature response to forced climate change over the last six centuries

“…The original composite was modified by using a catalog of volcanic eruptions [Sirekin and Siebert, 1993] to remove local eruptions, identify possible candidate eruptions to latitude-weight the forcing, and then convert the time series to radiative forcing by scaling the ice core time series to estimates of aerosol forcing from ground based observations [Sato et al, 1993]. New ice core estimates [Langway et al, 1995] …”