Extended Data Fig. 7: The effect of bioturbation on the 14C reconstruction at the Bølling transition.
From: Eurasian Ice Sheet collapse was a major source of Meltwater Pulse 1A 14,600 years ago
To assess the potential impact of bioturbation, we used the TURBO2 model149 (Methods). As input we used 1,024 simulated abundance vectors (gray; top panel) generated as normally distributed random values centered on the best-fit linear trend and with the standard deviation of the observed abundance of foraminifera in core MD95-221059 (top panel). If we assume a constant mixed layer depth of 6 cm, then the observed change in 14C age can be reproduced with reasonable accuracy in TURBO2 by invoking a hypothetical true 14C age with an abrupt step change 14.56 kyr ago (lower panel). This result is not an attempt to infer the true 14C age history, but rather to demonstrate that the effect of bioturbation would be to smear out the true event. As a consequence, our reconstruction is likely to overestimate the time scale of the EIS collapse and underestimate its contribution to the global MWP-1A.
