Global Climate Change and the Oceans

— The article analyzes the role of the ocean in climate change. The effects associated with the accumulation of anthropogenic heat by the ocean, as well as the formation of the ocean’s own changes on a scale of decades, are discussed. The flows of climatically active gases between the ocean and the atmosphere are considered. It is shown that, being the most conservative component of the climate system, the World Ocean absorbs ~92% of excess heat entering the system as a result of anthropogenic activity. This determines approximately 50–60% of the contribution to the rise in the level of the World Ocean due to the steric factor. It is also substantiated that the ocean is the only component of the climate system that has internal (intrinsic) variability modes with long (from a decade to several decades) time scales. These modes of variability (for example, the Atlantic Multidecadal Oscillation) form responses in the atmosphere (during the processes of interaction at the ocean–atmosphere interface), whose superposition with global trends significantly reduces the accuracy of climate forecasts. Finally, it is shown that the oceans and seas are the most powerful net absorbers of climatically active gases, primarily CO2. With the warming of the climate (and the simultaneous warming of the ocean and seas), the role of the ocean as a CO2 sink is slowly weakening. Moreover, with an increase in storm activity in the oceans and seas, this role also weakens, since storm activity leads to an increase in emissions. Thus, global and regional balances of greenhouse gases cannot be reliably estimated without taking into account the role of the ocean.