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Quantitative sporomorph data of five wells from the southern Central Graben (offshore, The Netherlands) and from two wells and an outcrop section from East Anglia (onshore, UK) are used to establish a Callovian-Early Ryazanian palaeoclimatic curve for the southern North Sea region. The palaeoclimate proxy record indicates subtropical temperatures and humid conditions for the Late Callovian and Early Oxfordian interval. Thereafter, the results show stepwise warming and aridization. The onset of this trend can be related to global palaeogeographical changes associated with the breakup of Pangea. The aridity and temperature reached their maximum development during the Late Kimmeridgian and Portlandian. In the earliest Cretaceous, the climate returned to slightly cooler, tropical and humid conditions. When combined with regional palaeogeographical reconstructions, these conditions suggest that the recorded Late Kimmeridgian to Portlandian arid phase may be linked to the arrival of cooler high latitude waters to the North Sea region due to the opening of the North Atlantic seaway connecting the warns Tethys Ocean in the south to the Boreal Ocean. (C) 2001 Elsevier Science B.V. All rights reserved.