The Abrupt Climate Changes and Environmental Responses (ACER) database (Sánchez Goñi et al., 2017) was originally developed to provide pollen and charcoal data for investigating past climate events. Since its publication, many additional records have been generated, but the original database has not been updated.

This dataset includes site metadata, age models, and pollen counts from all sites not included in the original ACER database. Extensive data validation has been carried out, including the correction of spelling errors, removal of duplicates caused by unnecessary spacing, and standardisation of taxonomic synonyms using Plants of the World Online (POWO) as a reference. Non-pollen taxa (e.g., fungi), obligate aquatics, mangroves, and carnivorous plants have been excluded.

Taxon names have also been harmonised to align with the terminology used in version 3 of the SPECIAL Modern Pollen Database (SMPDSv3). This includes the preservation of three levels of taxonomic harmonisation: CLEAN, INTERMEDIATE, and AMALGAMATED.