While in 1950 the chances of realising an ‘Elfstedentocht’ (Frisian Eleven-City Ice-Skating Marathon) were once every 4 years, scientists expect an Elfstedentocht once every 18 years for the present. This is evident from an article published today in the scientific journal Climatic Change, by researchers from the Netherlands Environmental Assessment Agency. Continuing global warming will lead to further diminishing chances of holding an Elfstedentocht.