Climate forcing reconstructions for use in PMIP simulations of the last millennium (v1.0)

The drivers of climate over this period are chiefly orbital, solar, volcanic, changes in land use/land cover and some variation in greenhouse gas levels. While some of these effects can be easily defined, the reconstructions of solar, volcanic and land use-related forcing are more uncertain.

We describe here the approach taken in defining the scenarios used in PMIP3, document the forcing reconstructions and discuss likely implications.