Volcanic stratospheric sulfur injections during the Holocene (past 11 500 years) from a bipolar ice-core array, HolVol version 1.1

Based on a set of continuous sulfate and sulfur records from four ice cores, one from Greenland and three from Antarctica, the HolVol v.1.0 database (Sigl et al., 2021, PANGAEA) included estimates of the magnitudes and approximate source latitudes of major volcanic stratospheric sulfur injection (VSSI) events for the Holocene (from 9500 BCE or 11 500 years BP to 1900 CE). In total, we reconstructed 850 volcanic eruptions with injections more than 1 teragram of sulfur (Tg S). These eruptions injected 7410 Tg S into the stratosphere. With the entire reconstructions based on the same four ice cores this reconstruction is best suited to study the frequency and spatial distribution of volcanic activity and resulting VSSI over long time periods and to study drivers and feedbacks between volcanism and climate through time (Sigl et al., 2022). Here we update the database to HolVol v.1.1 as follows: First, we replace the HolVol reconstruction younger than 500 BCE with a similar reconstruction (eVolv2k; Toohey & Sigl 2017) which is based on a larger network of ice cores with on average higher depth resolution and for which important eruption source parameters (i.e. SSI, latitude, eruption season) have been constrained through dedicated geochemical (e.g. cryptotephra, sulfur isotopes, trace element) analyses (eVolv2k_version4, Sigl & Toohey, PANGAEA, doi:10.1594/PANGAEA.971968). For consistency across the different datasets, we updated the default latitudes for unidentified volcanic eruptions suspected in the Northern Hemisphere extra-tropics from 45°N to 48°N, for those suspected in the Southern Hemisphere extra-tropics from 45°S to 37°S and for those suspected in the tropics from 0° to 5°N (with the latter values being the default latitudes for HolVol, calculated from the mean distribution of large volcanic eruptions in geologic eruption catalogues). Second, we updated strengths of VSSI, the timing and location of specific caldera-forming (VEI≥6) volcanic eruptions that we identified through geochemical fingerprinting (e.g. cryptotephra analysis; sulfur isotope analysis) and geochronological tools during the Mid-to-late Holocene using additional ice cores and new analyses (e.g. Aniakchak II, Crater Lake). The new HolVol v.1.1 database includes 1365 VSSI events between 9500 BCE to 2000 CE which injected in total 7370 TgS or 0.65 TgS per year on average. Dating uncertainties are +/- 1 to +/-3 years over the past 2,500 years, +/-5 years between 2000 BCE and 500 BCE, and less than +/-10 years before 2000 BCE.