Andrade, A., Rubio, B., Rey, D., Alvarez-Iglesias, P., Bernabeu, A.M. and Vilas, F. 2011. Palaeoclimatic changes in the NW Iberian Peninsula during the last 3000 years inferred from diagenetic proxies in the Ría de Muros sedimentary record. Climate Research 48: 247-259.
Working with a 2.5-m gravity core and an 18-cm box core taken from the outer area of the Ría de Muros (42°44'N, 9°02'W) on the northwestern coast of the Iberian Peninsula in June 2004, Andrade et al. established histories of numerous climate-related parameters, including quantities of 22 different elements (including total organic carbon, total nitrogen, and total sulfur), various materials' magnetic properties, δ13C values, as well as sediment color, texture and sedimentation rates. And based on these data, they identified a period of lesser oceanic influence between 1250 and 560 cal. yr BP that they identified as the Medieval Warm Period (MWP), during which there was an increase in continental input to both the continental shelf and the Ría de Muros. This period was sandwiched between two colder periods that they identified as the Dark Ages and the Little Ice Age, which three-period interval was in turn sandwiched between what they identified as the Roman Warm Period and what we call the Current Warm Period, respectively.