Motivated by the need to understand the contributions of anthropogenic carbon emissions to global warming and ocean acidification, Bärbel Hönisch has devoted most of her career to developing and applying geochemical proxies to reconstruct paleo ocean temperature, carbonate chemistry, and atmospheric pCO2. In particular, she and her students have led efforts to identify and quantify the physical and chemical influences on the partitioning of boron and its isotopes from seawater into biogenic carbonates, specifically foraminifera and corals. This work required years of painstaking laboratory-based culturing experiments of foraminifera involving the meticulous manipulation of carbonate system parameters, complemented by field-based studies of core top samples. The findings of this pioneering work now provide the basis for applying boron in fossil shells to reconstruct ocean pH.
Bärbel has also led the way in validating and applying results of the B calibration studies in reconstructing past ocean pH and pCO2 across climatically critical intervals of the Cenozoic. This includes investigations of Pleistocene glacial/interglacials and the mid-Pleistocene transition, the results of which support a high degree of sensitivity in climate and ice sheets to greenhouse gas forcing. She also extended the application of B isotopes to deeper time by reconstructing the long-term trend in seawater B isotopes (in benthic foraminifera), as well as applying the B proxies to the extreme greenhouse periods of the Eocene, most notably in quantifying the pH changes caused by ocean acidification during the Paleocene–Eocene Thermal Maximum. She also organized and led workshops focused on ocean acidification and the development of a community paleo-pCO2 database.
Bärbel has also taken on key leadership and editorial duties for the AGU oceanographic/paleoceanographic communities and has been recognized for her exemplary mentoring of students at Columbia University.
Bärbel Hönisch’s unwavering commitment to research, her collegiality and leadership, and her selfless community service merit recognition with the Dansgaard Award.
—James Zachos, University of California, Santa Cruz
The boron isotope (δ11B) proxy for seawater pH is a tried and tested means to reconstruct atmospheric CO2 in the geologic past, but uncertaint...