Fundamental hypotheses for OPERA:

 

Hypothesis 1: New high resolution records from speleothem, seagrass and estuary archives in and proximal to the Iberian Peninsula can provide a verifyable extension to the instrumental records. Systematic monitoring of environmental conditions in caves, and detailed measurement of marine proxies under present conditions, can improve the accuracy of calibrations and the quantitative value of the proxy-based atmospheric and marine reconstructions.

 

Hypothesis 2: Changes in AMOC may have forced shift in the large-scale atmospheric circulation which affected precipitation patterns in the Iberian Peninsula. During warm interglacial periods such as the current one, even modest changes in the North Atlantic circulation, of magnitude comparable to those projected for the coming centuries, had persistent and widespread impact on precipitation in the Iberian Peninsula. By combining new records of past variations in precipitation and ocean circulation with results from paleoclimate model simulations, we can improve our understanding of the mechanisms responsible for hydrological changes in the Iberian Peninsula

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Hypothesis 3: When increases in atmospheric CO2 result in dissolved CO2 concentrations higher than 19 uM, diatoms and coccolithophores reduce reliance on active carbon uptake for photosynthesis. In the case of coccolithophores, this will permit greater production of calcite coccoliths, which promote sinking organic carbon to the deep ocean. Geochemical and paleontological indicators of reduced reliance on active carbon uptake for photosynthesis and increased calcification by coccolithophores can be used to evaluate the adaptation of diatoms and coccolithophores to elevated atmospheric CO2 in natural ecosystems from the modern and past oceans.