New estimates of carbon transfer to terrestrial ecosystems between the last glacial maximum and the Holocene

Abstract

Ice core records of atmospheric CO2 show an ≈ 80 ppm rise between the last glacial maximum (LGM) and the mid‐Holocene during a corresponding world‐wide expansion of the terrestrial biomass and changes in ocean chemistry. Therefore, the absolute amount of carbon transferred to the atmosphere, probably from the oceans, remains uncertain. To address this issue, I evaluated changes in terrestrial ecosystem carbon storage and isotopic fractionations between the LGM and the mid‐Holocene using a process‐based terrestrial carbon cycle model forced with two general circulation model (GCM) simulations of each interval. The results indicate that global carbon storage in terrestrial ecosystems (vegetation and soils) increased by 668 Gt C during the last glacial–interglacial transition, a value within the range obtained from a revised global carbon isotope mass‐balance analysis (550–680 Gt C), and consistent with independent estimates from the marine isotopic record.