Reply to the comment on 'Environmental impact of the 73 ka Toba super-eruption in South Asia' by M. A. J. Williams, S. H. Ambrose, S. van der Kaars, C. Ruehlemann, U. Chattopadhyaya, J. Pal, P. R. Chauhan

Abstract

Haslam and Petraglia raise three broad questions concerning our paper ‘Environmental impact of the 73 ka Toba super-eruption in South Asia’, by Martin A. J. Williams, Stanley H. Ambrose, Sander van der Kaars, Carsten Ruehlemann, Umesh Chattopadhyaya, Jagannath Pal, Parth R. Chauhan [Palaeogeography, Palaeoclimatology, Palaeoecology 284 (2009) 295–314]. (a) What was the relationship between the 73 ka Toba eruption and the cold stade between the Dansgaard–Oeschger interstades 20 and 19? (b) What was the regional impact of the eruption on vegetation? (c) What was the possible effect of the eruption upon humans and mammals? In response to questions (a) and (b) we note that the 73 ka Toba eruption was followed by several centuries of intense cooling and wind-blown dust accession in the Greenland GISP2 ice core, by a change from forest to grassland or open woodland in central India (carbon isotopic analysis) and in the wider region (pollen analysis of a marine sediment core in the Bay of Bengal). In regard to (c), the genetic evidence is as yet too imprecisely dated to demonstrate causality as is the archaeological evidence cited by Haslam and Petraglia in favour of minimal impact. Future work supported by higher resolution chronologies than are presently available is needed to provide a less equivocal picture of the environmental impact of the 73 ka Toba eruption.