A synthesis of surface - temperature reconstructions shows ocean surface cooling from ad 1 to 1800, with much of the trend from 800 to 1800 driven by volcanic eruptions. (nature.com)
This has a direct effect on the minimum and maximum surface temperatures through retained heat from a higher thermal mass and surface cooling from increased evaporation. (realclimate.org)
However, decreased cloud cover is expected to cause surface cooling because clouds have a warming influence in spring. (skepticalscience.com)