A new bipolar ice core record of volcanism from WAIS Divide and NEEM and implications for climate forcing of the last 2000 years

Abstract

Volcanism is a natural climate forcing causing short‐term variations in temperatures. Histories of volcanic eruptions are needed to quantify their role in climate variability and assess human impacts. We present two new seasonally resolved, annually dated non‐sea‐salt sulfur records from polar ice cores—WAIS Divide (WDC06A) from West Antarctica spanning 408 B.C.E. to 2003 C.E. and NEEM (NEEM‐2011‐S1) from Greenland spanning 78 to 1997 C.E.—both analyzed using high‐resolution continuous flow analysis coupled to two mass spectrometers. The high dating accuracy allowed placing the large bi‐hemispheric deposition event ascribed to the eruption of Kuwae in Vanuatu (previously thought to be 1452/1453 C.E. and used as a tie‐point in ice core dating) into the year 1458/1459 C.E. This new age is consistent with an independent ice core timescale from Law Dome and explains an apparent delayed response in tree rings to this volcanic event. A second volcanic event is detected in 1453 C.E. in both ice cores. We show for the first time ice core signals in Greenland and Antarctica from the strong eruption of Taupo in New Zealand in 232 C.E. In total, 133 volcanic events were extracted from WDC06A and 138 from NEEM‐2011‐S1, with 50 ice core signals—predominantly from tropical source volcanoes—identified simultaneously in both records. We assess the effect of large bipolar events on temperature‐sensitive tree ring proxies. These two new volcanic records, synchronized with available ice core records to account for spatial variability in sulfate deposition, provide a basis for improving existing time series of volcanic forcing.

Climatic and societal impacts of a volcanic double event at the dawn of the Middle Ages

“…2c) shows some qualitative similarities to the ice core record, however there is a discrepancy of about one year in the timing of peak deposition from the 540 eruption. This offset might imply that the tropical eruption occurred in late 539 CE (rather than 540 CE), however it is also notable that the agreement is significantly improved if the Antarctic ice core record is shifted by +1 year, which can be justified given ice core chronological uncertainty (Sigl et al 2013).…”

“…Based on available sulfate flux records (Tables S1, S4), the 540 CE event can be placed in the tropical eruption category, with a 2:1 Greenland-to-Antarctic sulfate flux ratio, similar to that of the eruptions of Huaynaputina (1600, 16°S) and Cosiguina (1835, 13°N). The 536 event has a strong signal in Greenland ice cores, and while a corresponding signal is undetectable in most Antarctic ice cores, a small signal was reported in the high resolution West Antarctic Ice Sheet (WAIS) Divide ice core record (Sigl et al 2013), suggesting some degree of cross-equator stratospheric transport. The resulting Greenland-to-Antarctic sulfate flux ratio of more than 10:1 can be safely assumed to be representative of a mid or high latitude NH eruption, which is consistent with detection of tephra in a Greenland ice core consistent in chemical composition to NH volcanoes (Sigl et al 2015).…”

“…Available total sulfate flux (kg/km 2 ) derived for the 536 and 540 events from Antarctic and Greenland ice cores (Traufetter et al 2004;Larsen et al 2008;Plummer et al 2012;Sigl et al 2013) are listed in Table S1. To account for potential sampling bias from the small number of available ice cores available for this time period, and the spatial variability of sulfate deposition to the surface (e.g., Sigl et al 2014), Antarctic and Greenland averages are corrected using scaling factors derived from MAECHAM5-HAM simulations (Supplementary Methods, (Niemeier et al 2009;Toohey et al 2011;Toohey et al 2013)).…”

Multi-model comparison of the volcanic sulfate deposition from the 1815 eruption of Mt. Tambora

“…due to marine biogenic sulfur emissions) is calculated in each ice core (the non-volcanic contribution) and a threshold flux 15 value is chosen, above which sulfate is assumed to be of volcanic origin. The ice core-derived volcanic sulfate deposition flux is then calculated as the difference between a year with the volcanic contribution and the mean of the non-volcanic years, and the resulting reported volcanic sulfate deposition flux is the sum of the fluxes in these perturbed years (Ferris et al, 2011;Cole-Dai et al, 2013;Sigl et al, 2013). Our comparable model-simulated volcanic deposition flux is calculated as the sum of the sulfate deposition anomaly (perturbed run minus control run) over the duration of the deposition signal (~2-4 20 years).…”

Influence of Solar Retrograde Motion on Terrestrial Processes

“…These data can be found at http://www.ncdc.noaa.gov/paleo/icecore/ antarctica/domec/domec. New data on volcanic aerosol concentrations in the stratosphere over the last 2000 years were obtained in (Clausen et al, 2012;Sigl et al, 2013). Below, we use data from (Sigl et al, 2013).…”