Algal constraints on the Cenozoic history of atmospheric CO 2 ?

• Main Authors: Henderiks, J., Rickaby, R. E. M.
• Other Authors: Department of Geology and Geochemistry Stockholm, Stockholm University, Department of Earth Sciences Oxford, University of Oxford Oxford
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2007
• Subjects: [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]; [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; ice core; Ocean acidification
• Online Access: https://hal.archives-ouvertes.fr/hal-00297858; https://hal.archives-ouvertes.fr/hal-00297858/document; https://hal.archives-ouvertes.fr/hal-00297858/file/bgd-4-1-2007.pdf

International audience An urgent question for future climate, in light of increased burning of fossil fuels, is the temperature sensitivity of the climate system to atmospheric carbon dioxide (pCO 2 ). To date, no direct proxy for past levels of pCO 2 exists beyond the reach of the polar ice core records. We propose a new methodology for placing an upper constraint on pCO 2 over the Cenozoic based on the living geological record. Specifically, our premise is that the contrasting calcification tolerance of various extant species of coccolithophore to raised pCO 2 reflects an "evolutionary memory" of past atmospheric composition. The different times of first emergence of each morphospecies allows an upper constraint of past pCO 2 to be placed on Cenozoic timeslices. Further, our hypothesis has implications for the response of marine calcifiers to ocean acidification. Geologically "ancient" species, which have survived large changes in ocean chemistry, are likely more resilient to predicted acidification.