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The world oceans, global climate drivers The climatesystem, its subsystemsandrelevant processesand inter actions.Air-iceinteractionAir-oceaninteractionInfluxSea iceCurrentBIOSPHERERiversLakesHumaninterventionIce-oceaninteractionPEDOSPHERELITHOSPHEREdictability is around 14 days. Currents in the deep sea,however, require several centuries to react fully to changingboundary conditions such as variations in the NorthAtlantic oscillation, which cause changes in temperatureand precipitation at the sea surface and thus drive motionat greater depths. A large continental ice mass such asthe Antarctic ice sheet, as a result of climate change, presumablyundergoes change over many millennia, andwithout counteractive measures it will gradually melt onthis time scale. The predictability of climate is based onthe interactions between the atmosphere and the moreinert climate subsystems, particularly the oceans. Withinthis scheme, the various components of the climate systemmove at completely different rates. Low-pressuresystems can drift hundreds of kilometres within days.Ocean currents, on the other hand, often creep along at afew metres per minute. In addition, the individual componentspossess different thermal conductivities andheat capacities. Water, for instance, stores large amountsof solar heat for long periods of time.Climate changes can be triggered in two differentways – by internal and external forces. The internalforces include:• Changes in a single climate component, for example,an anomalous ocean current;• Changes in the interactions between different climatecomponents, for example, between the ocean andatmosphere.Compared to these, the external mechanisms at firstglance appear to have nothing to do with the climate system.These include:• The very slow drift of continents, which moves landmasses into different climate zones over millions ofyears;• The changing intensity of radiation emitted by the sun.The radiation energy of the sun fluctuates over timeand changes temperatures on Earth;• Volcanic eruptions, which inject ash and sulphur compoundsinto the atmosphere, influence the Earth’sradia tion budget and thus affect climate.