Limitations of dinoflagellate cyst transfer functions

Organic-walled dinoflagellate cysts have become an important proxy for reconstructing Quaternary sea-surface conditions, with transfer functions generating quantitative estimates of summer and winter sea-surface temperatures, salinity, and ice cover. I critically reassess these transfer functions and argue that the uncertainty of the summer temperature and ice cover transfer functions has been substantially underestimated because the strong spatial structure in the data set has been ignored, and that there is little evidence that either winter sea-surface temperature or salinity can be independently reconstructed.