Table 2.

Eruption dates and cumulative sulfate SO₄^2- deposition at ice-core sites in Greenland and Antarctica for V1 to V7, with five additional events revealed through new analysis and three more recent analogues with known source and date. Dating is given according to known calendar dates or dates applied in this study. ‘GRL Mean’ includes mean sulfate deposition from Dye 3 and GRIP (23) for V2 (Aniakchak II) V3, Okmok II, and Tambora. ^a indicates association with a bristlecone pine frost-ring within ±1 year of ring-width minima in 43 BCE, 1627 BCE, and 1653 BCE (5). Blanks indicate ‘no data’. ^b sulfur injections are 3 (±1) and 2 (±1) Tg for the alternative attribution scenario of two distinct eruptions. Due to the low temporal resolution in GISP2 and discontinuous sampling in NGRIP, the volcanic sulfate deposition for V3, evident in electrical records from NGRIP and EGRIP (33) was estimated based on published discontinuous data from the GRIP and Dye-3 ice core (23).

Eruption date							Asymmetry	Source	SO42-	Sulfur
	SO42−	SO42−	SO42−	SO42−	SO42−	SO42−			burden	Injection
	[kg km−2]									[Tg S]
1883 CE	22	29	15	16	21	11	0.59	Krakatau	Bipolar	13 ± 3
1815 CE	36	54	40	65	87	44	0.35	Tambora	Bipolar	34 ± 7
43 BCE	117	123	122	20	24	15	0.86	Okmoka	Bipolar	48 ± 15
1539 BCE	16	16	–	3	6	0	0.85	V7	Bipolar	6 ± 2
1550 BCE	12	12	–	40	44	36	0.23	V6	Bipolar	17 ± 3
1555 BCE	17	17	–	17	0	37	0.92		Bipolar	6 ± 2
1558 BCE	27	27	–	3	0	6	0.90		Bipolar	10 ± 3
1561 BCE	57	91	70	7	0	15	0.89	V5	Bipolar	22 ± 7
1573 BCE	0	0	0	10	19	0	0.00		SH	2 ± 1
1586 BCE	55	79	30	0	0	0	1.00	V4	NH	10 ± 4
1611 BCE	16	0	–	10	15	5	0.62	V3	Bipolar?	8 ± 2b
1628 BCE	137	185	147	19	16	22	0.88	Aniakchaka	Bipolar	52 ± 17
1654 BCE	105	120	91	45	52	38	0.70	V1a	Bipolar	50 ± 13
1658 BCE	8	8	–	7	6	8	0.54		Bipolar	5 ± 1
1678 BCE	55	55	–	5	6	4	0.92		Bipolar	20 ± 7