Abstract: A method and associated system for regulation of the cooling capacity of a cooling system that uses a gas expansion cooling circuit where the cooling principle is expansion of one or more gaseous cooling medium streams from a higher pressure to a lower pressure are described, characterised by the following steps: —reducing the amount of cooling medium which is circulated in the cooling circuit (100) temporarily in that a fraction of gaseous cooling medium is pre-cooled at a higher pressure and is extracted from the cooling circuit (100), —expanding the fraction of cooled gaseous cooling medium across an expansion device (102) to a lower pressure so that at least one part of liquid cooling medium separates, —separating the liquid from the non-condensed gas for temporary storage in a storage unit (104) so that the liquid is temporarily not circulated in the otherwise closed cooling circuit (100), —thereafter to return temporarily stored gaseous cooling medium from the storage unit (104) to the cooling circuit (