Response to reviewer RC2 comments

Abstract

The biological production of calcium carbonate (CaCO 3), a process termed calcification, is a key term in the marine carbon cycle. A major planktonic group responsible for such pelagic CaCO 3 production (CP) is the coccolithophores, single-celled haptophytes that inhabit the euphotic zone of the ocean. Satellitebased estimates of areal CP are limited to surface waters and open-ocean areas, with current algorithms utilising the unique optical properties of the cosmopolitan bloom-forming species Emiliania huxleyi, whereas little understanding of deep-water ecology, optical properties or environmental responses by species other than Published by Copernicus Publications. 1860 C. J. Daniels et al.: A global compilation of coccolithophore calcification rates E. huxleyi is currently available to parameterise algorithms or models. To aid future areal estimations and validate future modelling efforts we have constructed a database of 2765 CP measurements, the majority of which were measured using 12 to 24 h incorporation of radioactive carbon (14 C) into acid-labile inorganic carbon (CaCO 3). We present data collated from over 30 studies covering the period from 1991 to 2015, sampling the Atlantic, Pacific, Indian, Arctic and Southern oceans. Globally, CP in surface waters (< 20 m) ranged from 0.01 to 8398 µmol C m −3 d −1 (with a geometric mean of 16.1 µmol C m −3 d −1). An integral value for the upper euphotic zone (herein surface to the depth of 1 % surface irradiance) ranged from < 0.1 to 6 mmol C m −2 d −1 (geometric mean 1.19 mmol C m −2 d −1