Given current emission trends, atmospheric CO2 in coming centuries is likely to reach levels last seen millions of years ago, with significant impacts on climate as well as on marine and terrestrial ecosystems. In this project, by means of an interdisciplinary approach that combines proxy records and climate modeling, we examine two key environmental areas particularly sensitive to this anticipated anthropogenic change: 1) hydrological variability in the Iberian Peninsula and its relationship to changes in ocean circulation and 2) the response of marine ecosystems to elevated levels of CO2.